CAP-304

REV D (OCT 2016)

RS Series
OIL-INJECTED ROTARY SCREW COMPRESSORS

OPERATOR
MANUAL
RSD-50 RSD-60 RSD-75
RSD-100 RSD-125 RSD-150
RSD-200 RSD-250 RSD-300
 FOREWORD

The Curtis-Toledo R/SD Series compressor unit utilizes a single stage rotary screw air end, direct
driven by an electric motor. The package includes the oil injected compressor (air end), motor,
motor controls, air intake system, air/oil separator, cooling system and compressor instru-
mentation.

Curtis-Toledo designs the R/SD Series compressors for indoor installation. They are available
with or without an enclosure.

This manual is written to aid the user in the installation, maintenance and daily operation of your
compressor. We urge you to read and follow these instructions for the safe and economical
operation of this unit.

Electricity and compressed air have the potential to cause severe personal injury and or property
damage. Before installing, wiring, starting, operating or making any adjustments identify the
components of the air compressor using this manual as a guide.

Qualified personnel adequately equipped with the proper tools should perform maintenance.
Follow the maintenance schedules as outlined in this manual to insure problem free operation
after initial start-up.

The operator should use common sense and good working practices while operating and
maintaining this unit.

Safety instructions in this manual are bold-faced for emphasis. The signal words DANGER,
WARNING, CAUTION and NOTICE are used to indicate hazard seriousness levels as follows:

DANGER
Danger is used to indicate the presence of a hazard that will cause severe personal
injury or death and /or substantial property damage.

WARNING

Warning is used to indicate the presence of a hazard that can cause severe personal
injury and /or substantial property damage.

CAUTION

Caution is used to indicate the presence of a hazard that can cause personal injury
and/or property damage.

NOTICE

Notice is used to inform the user of installation, operation or maintenance information

that is important but not of a hazardous nature.

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 ENGINEERING DATA

R/SD R/SD R/SD R/SD R/SD R/SD R/SD R/SD R/SD

MODEL
50 60 75 100 125 150 200 250 300
OIL (GAL.)
8 15 15 15 25 25 40 50 50
CAPACITY
AIR (IN.)
1½ 1½ 2 2 2 2 2½ 3 3
CONNECTION
OIL G.P.M. 20 25 28 32 46 50 55 65 90
MOTOR RPM 1750 3500 1450 3500 1750 1750 1750* 1750 1750
BTU/M
2000 2100 2900 3850 4900 5860 7500 9400 11250
OIL COOLER
BTU/M
300 400 550 750 915 1100 1500 1850 2200
AFTERCOOLER
COOLING
8000 9500 12500 16000 18000 22500 22500 28000 28000
FAN CFM
MOTOR
6 5 5 4 3 3 3 2 2
STARTS/HR MAX

SUBJECT TO CHANGE WITHOUT NOTICE

*MOTOR RPM 3500 ON NON-GEARED MODEL

STANDARD EQUIPMENT

1. Dry Type Inlet Filter / Silencer 13. Separate Fan Motor and Starter on Air cooled
2. Oil Filter 14. Hour meter
3. Motor / Compressor Drive Coupling 15. High Temperature Shut Down Switch with Light
4. Drive Guard 16. Oil Level Sight Glass
5. Multi Stage Oil Separator Unit 17. Start – Stop Push Buttons
6. ODP Motor, 60 Hz, 1.15 SF 18. Modulating Control
Water Temperature Control Valve and on Water
7. Safety Valve 19.
Cooled Units
8. Pressure Gauge 20. Minimum Pressure Valve
9. Temperature Gauge 21. Factory Fill Lubricants
10. Oil Cooler 22. Thermostatic Oil Valve
11. Nema 1 Control 23. Low Unloaded H.P. Blow Down System
Steel Base with Isolated Motor / Compressor
12. 115 Volt Control Transformer 24.
Base

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 REPAIR PARTS ORDERING

When ordering repair parts specify compressor model and serial number (see the nameplate
located on the control panel and note in the space provided below).

Consult the appropriate parts list specific to your compressor. This parts list was packed with your
compressor when it was shipped from the factory.

Contact your local Curtis – Toledo authorized dealer who can supply you with the correct genuine
Curtis replacement part.

Your authorized local distributor can supply you with the following services:

• Factory warranty service.

• A full line of CurtisLubePlus factory tested compressor lubricants specifically formulated for
use in Curtis compressors.
• Repair and maintenance kits with the necessary parts to get your compressor up and running
with a minimum of down time.

For the name of your local Curtis distributor contact:

Curtis – Toledo Inc.

1905 Kienlen Ave.
St. Louis, Missouri 63133
Phone: 314-383-1300
Fax: 314 381 1439
E-mail: info@curtistoledo.com

Note your model and serial number here for reference when ordering parts or
calling for service:

Hours

CAUTION

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 TABLE OF CONTENTS

FOREWORD…………………………………………………………………………………………… i

MODELS COVERED IN THIS MANUAL…………………………………………………………… ii

REPAIR PARTS ORDERED…………………………………………………………………………. iii

SECTION 1, GENERAL SAFETY…………………………………………………………………… 1

SAFETY DECALS……………………………………………………………………………… 2

SECTION 2, GENERAL DESCRIPTION…………………………………………………………… 4

COMPRESSOR……………………………………………………………………………….. 4
AIR/OIL FLOW…………………………………………………………………………………. 5

SECTION 3, INSTALLATION………………………………………………………………………... 6
GENERAL………………………………………………………………………………………. 6
LOCATION……………………………………………………………………………………… 6
INLET AIR………………………………………………………………………………………. 7
COOLING AIR DISCHARGE…………………………………………………………………. 7
WATER COOLED UNITS…………………………………………………………………….. 7
ELECTRICAL CONNECTIONS………………………………………………………………. 8
COMPRESSOR ROTATION………………………………………………………………….. 8
OIL LEVEL CHECK……………………………………………………………………………. 8
STORAGE………………………………………………………………………………………. 9
FREIGHT DAMAGE PROCEDURE………………………………………………………….. 9

SECTION 4, OPERATION…………………………………………………………………………… 11
GENERAL………………………………………………………………………………………. 11
OPERATING MODES…………………………………………………………………………. 11
COMPONENT DESCRIPTION……………………………………………………………….. 12
INITIAL START-UP…………………………………………………………………………….. 15
SHUTTING DOWN THE COMPRESSOR…………………………………………………... 15

SECTION 5, MAINTENANCE……………………………………………………………………….. 17
GENERAL………………………………………………………………………………………. 17
AIR FILTER……………………………………………………………………………………... 17
LUBRACANT……………………………………………………………………………………. 18
SEPARATOR ELEMENT……………………………………………………………………… 19
SCAVENGER LINE OIL SIGHT GLASS…………………………………………………….. 20
THERMAL BY-PASS VALVE…………………………………………………………………. 20
MINIMUM PRESSURE VALVE………………………………………………………………. 21
FAN………………………………………………………………………………………………. 22
INLET VALVE…………………………………………………………………………………... 22
OIL COOLER…………………………………………………………………………………… 23
DRIVE SYETEM……………………………………………………………………………….. 24
MAINTENANCE SCHEDULE…………………………………………………………………. 25
TROUBLESHOOTING…………………………………………………………………………. 26

SECTION 6, SPECIFICATIONS……………………………………………………………………... 30
DIMENSIONAL DATA ……………………………………………………………………….... 31
PNEUMATIC DIAGRAM………………………………………………………………………. 32
WIRING DIAGRAMS…………………………………………………………………………… 33
RECOMMENDED BOLT TORQUE…………………………………………………………... 36
SEPARATOR TANK LID BOLT TORQUE…………………………………………………... 37
COMPRESSOR MAINTENANCE LOG……………………………………………………… 37

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 CAP304

SECTION 1

GENERAL SAFETY

As with any piece of rotating equipment common In addition to the obvious safety rules we
sense safety precautions should be used in the recommend additional safety precautions as listed
operation of this rotary screw air compressor. below. Please read and follow these precautions for
Carelessness can be very hazardous to personnel. the safe day-to-day operation of your compressor.

1. Read and understand all the instructions found in this manual before operating this compressor.
2. Disconnect the main power source before working on or performing any maintenance procedures
on this unit.
3. Do not attempt to remove any parts, break any connection, loosen oil fill plug or drain plug until the
unit has been shut down and air pressure has been relieved.
4. Do not operate the compressor in excess of its rated pressures and speeds indicated on the
compressor nameplate,
5. Do not remove guards, shields, or screens while the compressor is in operation. If removed for
maintenance replace before resuming operation.
6. Observe the delivery pressure gauge daily to be sure the automatic control system is operating
within proper limits.
7. Periodically check all safety and relief devices for proper operation.
8. Do not play with compressed air. Pressurized air can cause serious injury to personnel.
9. Be sure that no tools, rags or loose parts are left on the compressor or drive parts.
10. Do not use flammable solvents for cleaning parts.
11. Exercise cleanliness during maintenance and when making repairs. Keep dirt away from parts and
exposed openings by covering with clean cloth or Kraft paper.
12. Do not install a shut-off valve in the discharge line without installing a pressure relief valve
between the shut-off and the compressor package.
13. Do not operate the compressor in areas where there is a possibility of ingesting flammable or toxic
gases.
14. Never disconnect (or jump) the air discharge temperature switch and attempt to operate the
compressor.
15. Know what mode of operation the compressor is in before working around the unit. The power
may be on but the machine not running if it is in the auto restart mode.

Make sure to investigate the local code require- ceeding list of safety precautions is all-inclusive or
ments in your area to ensure compliance prior to that the observance of this list will prevent all injury
installing the compressor. or property damage.

The owner, lessor or operator of this com- Cutis-Toledo expressly disclaims responsibility or
pressor is hereby notified and forewarned that liability for any injury or property damage caused by
failure to observe these safety precautions may failure to follow these specified precautions or by
result in injury and/or property damage. failure to exercise ordinary caution and due care re-
quired in operating or handling this equipment even
Curtis-Toledo does not mean to imply that the pre- though not expressly specified.

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SAFETY DECALS

Your compressor is posted with several safety where the hazard is most prevalent on the
decals to inform the user of hazards associated compressor. The decals used are shown below.
with its operation. These decals are positioned

WARNING WARNING

DO NOT REMOVE FILL PLUG VARIOUS PARTS OF THIS EQUIPMENT

WHEN COMPRESSOR IS IN MAY HAVE HOT SURFACES AND
COULD CAUSE SEVERE BURNS.
OPERATION DO NOT TOUCH.
WAIT UNTIL AIR PRESSURE TO AVOID BURNS, KEEP HANDS AND
ALL PARTS OF THE BODY AWAY.
IS COMPLETELY RELIEVED.

VENTED PLUG - REMOVE SLOWLY DO NOT REMOVE OR

DO NOT OVERFILL DEFACE DECAL.
QAB546 QAB561

WARNING WARNING

TOXIC, VOLATILE, AND CORROSIVE ALL ELECTRICAL ENCLOSURES,

VAPORS CAN CAUSE PERSONAL
INJURY OR PROPERTY DAMAGE. CABLE WIRING AND COMPONENTS
LOCATE COMPRESSOR INTAKE TO MUST BE INSTALLED AND
AVOID SUCH CONDITIONS.
GROUNDED IN ACCORDANCE WITH
-OPERATE WITHIN RECOMMENDED
NFPA, NATIONAL ELECTRICAL
TEMPERATURE RANGE.
-PROVIDE ADEQUATE VENTILATION. CODE AND APPLICABLE STATE
TEMPERATURE RANGE. AND LOCAL CODES.
DO NOT REMOVE OR DO NOT REMOVE OR
DEFACE DECAL. QAB561
DEFACE DECAL. QAB560

WARNING WARNING
PRESSURE SWITCHES
PRESSURE SWITCHES
HAVE BEEN HAVE BEEN
PROPERLY SET AND PROPERLY SET AND
TESTED BY THE TESTED BY THE
FACTORY. DO NOT FACTORY. DO NOT
ADJUST SETTING ADJUST SETTING
UP OR DOWN WITH UP OR DOWN WITH
OUT NOTIFYING
OUT NOTIFYING
FACTORY SERVICE.
FACTORY SERVICE.

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WARNING CAUTION
OIL CHANGE INTERVAL
Recommended oil change intervals are based on oil
temperature. The following table indicates how oil life
is affected by temperature:
Discharge RS8000
Temperature Change Interval
Up to 180° F 8000 Hrs.
180 to 190° F 6000 Hrs.
190 to 200° F 4000 Hrs.
200 to 210° F 2000 Hrs.
Sustained operation above 210° F could cause varnishing
and damage to the compressor.

UNIT CAN AUTOMATICALLY

In addition, high humidity and unclean operating conditions
RESTART. require more frequent oil changes. Appearance of the oil
CAN CAUSE PERSONAL INJURY must be examined periodically and oil change intervals
DISCONNECT ALL POWER adjusted by the user.
SUPPLIES TO ALL COMPONENTS OIl must be changed a minimum of once a year or more
BEFORE OPENING ENCLOSURE
often as indicated above in order to maintain warranty
OR SERVICING.
coverage. It is highly recommended to use Curtis RS8000
DO NOT REMOVE OR
Oil which has been specially formulated for use with this
DEFACE DECAL. QAB547 compressor
QAB709

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 CAP304

SECTION 2

GENERAL DESCRIPTION

COMPRESSOR

The compressor assembly is an oil flooded, In operation as depicted below in the compression
positive displacement, single stage, helical screw cycle (Ref. Figure 2-2), air entering the compressor
type unit consisting of two rotors or screws through the inlet port becomes trapped between
supported axially by roller bearings and enclosed in the helical lobes of the main rotor and the matching
a housing or stator as depicted in the sectional grooves of the secondary rotor (A). As the rotors
view Figure 2-1. turn air is trapped in the cavity created by the
mashing lobe and groove and reduced in volume or
“compressed”. It is then pushed through the suc-
cessive cavities (B) until it reaches the discharge
end of the compressor (C) and is sent to the oil
separator.

During the compressor cycle, oil is injected into the

compressor for the purpose of dissipating the heat
of compression and to seal the internal clearances.
The compressed air laden with oil leaves the com-
pressor through the discharge port and enters a
reservoir where the oil and air are separated. This
process delivers a smooth flow of compressed air
Figure 2-1 at the desired pressure.
Compressor Assembly

INLET
SECONDARY
ROTOR

MAIN ROTOR
A B C DISCHARGE

Figure 2-2
Compression Cycle

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AIR/OIL FLOW

Air enters the compressor through the air filter and cooled and discharged to its point of usage.
air inlet valve where it is mixed with oil. After
compression the air/oil mixture is discharged into A sufficient amount of oil is stored in the oil
the oil separator where its velocity is reduced separator tank and is forced by the pressure of
causing most of the oil to drop to the bottom. The compression from the sump to the thermal by-pass
remaining oil is removed as the air passes through valve, which regulates its flow into the oil cooler
the separator element. Oil collected at the bottom depending on the temperature of the oil. The ther-
of the separator element is returned to the inlet of mal valve will open when the oil reaches a
the compressor through the scavenger line that is predetermined temperature allowing the hot oil to
equipped with a sight glass for monitoring the flow enter the cooler. Oil, which has not reached this
of oil to determine when separator replacement is temperature setting, will by-pass the cooler.
necessary. The coalesced air then passes through
the minimum pressure valve set to maintain a min- The oil is then filtered and sent to the compressor
imum of 70 PSI in the oil separator to ensure a to initiate the compression cycle. The oil also
sufficient flow of oil to the compressor. The com- serves as lubrication for the compressor bearings.
pressed air then enters the aftercooler where it is

MINIMUM
PRESSURE
VALVE
AIR

AIR
FILTER
DISCHARGE SEPARATOR
AIR ELEMENT

OIL INLET
AIR/OIL VALVE
OIL AIR
/OI
COOLER OIL
L

SEPARATOR
OIL
FILTER OIL
FILL

OIL OIL
OIL
THERMAL LEVEL
BY-PASS GAUGE
VALVE

OIL

OIL
DRAIN
VALVE

Figure 2-3
Air/Oil Flow

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SECTION 3

INSTALLATION

GENERAL LOCATION & FOUNDATION

Upon receipt of your compressor inspect for freight Careful planning is required prior to the installation
damage. Report any damage as soon as possible. of the compressor unit. Choosing an improper
See “FREIGHT DAMAGE PROCEDURES” at the installation location may cause unnecessary
end of this section. trouble or damage to the operation of the
compressor resulting in poor performance and low
We recommend that the compressor remain on its quality of compressed air.
shipping skid until it reaches the final installation
site. Your Curtis Rotary Screw compressor unit does
not require a special foundation to operate.
The base of the compressor is equipped with lifting However, it is necessary that the floor be level and
notches for forklift removal from the shipping skid. that the base of the unit be adequately supported.
If a crane is used to lift the compressor we recom- Consult the “SPECIFICATIONS” section of this
mend the use of a spreader bar and chains. manual for the weight and dimensions of your
model. We also recommend the compressor be
bolted to the floor.

Lift the compressor unit by the base plate only. Allow at least three (3) feet clearance on all sides
Do not attempt to lift the unit using such places of the compressor to facilitate maintenance and
as the motor, compressor or discharge piping allow for free circulation of air. The unit should be
as lifting points. located in a clean, well-lighted area with low
relative humidity. The environment temperature
should not exceed 105°F. The reason for this is
that the higher the temperature the smaller the
output of air the compressor is capable of
The eyebolts provided on the motor are for producing. (Reference Figure 3-1)
lifting the motor only and should not be used to
lift any additional weight.

If the compressor is installed in an

airtight room, it is necessary to
provide plenum exhaust ventilation.
(Reference Figure 3-2)

Figure 3-1
Compressor Location

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OUTDOOR INSTALLATION – The standard R/S If it is necessary for inlet air to be taken from an
Series was designed for indoor installation only. outside source, the piping should be at least the
Installation in an outdoor, unsheltered area should diameter of the air filter inlet. If the distance is over
be avoided. The unit must be protected against twenty (20) feet the diameter needs to be enlarged
rain, snow and freezing temperatures. If outdoor to reduce restriction. The piping must be corrosion
installation is unavoidable contact the factory for resistant and cleaned thoroughly after fabrication.
modifications. Failure to obtain factory approval will The inlet must be protected to prevent rainwater
void the warranty. and small animals from entering the inlet piping.

Any unsheltered installation must have at least the

following modifications COOLING SYSTEM (Air Cooled Units)
• NEMA 4 controls
• TEFC motors Your compressor is equipped with an air/oil cooler.
• Weather resistant cabinet On air-cooled units the cooling fan is of sufficient
• Freeze protection (if applicable, see “COLD size to provide adequate cooling of the compressed
WEATHER OPERATION” air and the compression oil passing through this
cooler. We recommend a thorough cleaning of the
COLD WEATHER OPERATION – The unit should cooler fins periodically by vacuum or compressed
be installed inside a shelter heated to temperatures air to insure a restriction free flow of air from the
above freezing (32°F) If installation must be in an cooling fan through the oil/air cooler. Refer to
unheated area the following conditions must be met Figure 3-2 for minimum airflow through the unit.
to keep the compressor warranty intact:

1. All control lines and drain lines must be heated

to avoid freezing. Inadequate airflow will cause the compressor
2. The oil separator must be heated to maintain to run hot which can cause damage to the
viscosity during idle periods. compressor and increase oil carryover.
3. CURTIS LUBE PLUS RS-8000 synthetic oil
must be used.
Minimum Air Flow
Low temperature kits are available through the Model CFM M³/Min
factory. Contact your local Curtis compressor 50AD 11,600 328
distributor for details. 50D 11,600 328
60D 11,700 331
INLET AIR 75D 14,400 408
100D 18,800 532
A clean air supply is required for the satisfactory 125D 28,600 810
operation of your compressor. 150D 28,800 816
200D 31,000 878
250D 35,200 997
300D 35,300 1,000
Inlet air must not contain any flammable or Figure 3-2
toxic gases. These gases will be concen- Air Flow Rates
trated by the compressor and could result in
property damage, personal injury or death. WATER COOLED UNITS

The cooling water supply should be checked to

The inlet air filter supplied with the compressor is of
make sure the flow is sufficient. The chart shown in
sufficient size and design to meet all normal
FIGURE 3-3 lists approximate minimum water flow
operating conditions.
rates in U.S. gallons per minute at various
temperatures into the heat exchanger(s). The water
flow rate shown will cool the compressor oil to
approximately 140° F. The compressor operating
Inlet air containing reactive gases will cause temperature should be maintained at 160° F to
failure of the lubricant and compressor. 180° F under most conditions. The water outlet
Insure an air supply that is well clear of any temperature from the heat exchanger will be
reactive gases.

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 CAP304

approximately 110° F, which is the maximum

recommended to prevent heat exchanger tube
fouling and corrosion. Higher than listed water flow
rates will decrease the water outlet temperature. Failure to properly ground the compressor unit
could result in controller malfunction.
Inlet Water Temperature
HP
60°F 70°F 80°F 90°F
50 5.5 6.5 8.5 13.0 We recommend the use of a fusible disconnect for
60 7.0 8.5 11.5 16.5 isolating the unit. The fuse should be sized per
75 7.8 10.0 13.0 19.0 article MEC1430.52. Consult the Code if using
100 11.0 13.5 17.5 26.0 another style of branch circuit protection.
125 14.0 18.0 23.5 35.5
150 17.0 21.0 28.0 41.5
COMPRESSOR ROTATION
200 24.0 30.0 40.0 59.0
250 32.0 38.0 48.0 67.0
After the electrical wiring has been properly con-
300 40.0 47.0 58.0 81.0
nected check for proper rotation by momentarily
starting and stopping the motor. A directional arrow
FIGURE 3.3 is affixed to the compressor drive end.
Water Flow Rates (U.S. gal/min)

The size of the incoming water supply piping

should be at least equal to the connections
provided with the compressor Reverse rotation will cause air end damage.
Never allow the compressor to run in reverse
rotation as property damage or personal
injury may occur.
Water-cooled units must not be exposed to
freezing temperatures below 40°F., 4.4°C.
OIL LEVEL CHECK

Your compressor was shipped from the factory

ELECTICAL CONNECTIONS charged with the correct amount of compressor oil.
However, the oil level must be checked at instal-
All internal wiring has been done at the factory. lation and again prior to start-up. The combination
Wiring of the power supply to the compressor oil fill and sight glass is located on the side of the
should be done by a qualified electrician to comply separator tank. The oil level should be at the center
with the National Electric Code, state code, and of the mark when the unit is off. (See FIGURE 3-4)
any local codes in accordance with the wiring
diagram specific to your compressor model shown
in the “SPECIFICATIONS” section of this manual.

Electrical shock can cause severe injury or

death. Disconnect all power supplies, lockout
and tag before working on unit.

Oil level must be at

The power supply should be adequate and free of center of sight glass
parasitic loads that will cause an under voltage
condition during compressor operation.
FIGURE 3-4
The power source should be connected through a Oil Fill – Sight Glass
fusible disconnect and properly grounded in
accordance with the National Electric Code and
any other applicable codes.

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 CAP304

STORAGE

In some cases it may be necessary to store the 6. Curtis-Toledo will accept the shipment back,
compressor for extended periods of several months repair the damage (under normal conditions)
before putting it into service. When this is required and return the unit within (7) working days.
observe the following recommendations. 7. We will invoice the customer for the repair,
1. Cover and seal all machine openings to which will then become part of your claim. The
prevent the entrance of water and dirt. invoice must be presented to the trucking
2. Cover all openings in open drip proof motors. company claim department along with their
3. If the storage conditions are below freezing, completed claim form.
drain the aftercooler, traps, water-cooled heat
exchangers and attendant piping. We do not If the damage can be repaired at the receiving point
recommend outside storage. follow procedure steps 1 through 4a. Repair the
4. Cover with a waterproof tarpaulin that can unit and present a detailed invoice to the trucking
easily be removed for in storage maintenance. company showing labor hours, labor rate, materials
5. While in storage, rotate the compressor and used and cost of the materials.
motor by hand every thirty to sixty days to
prevent flat spots on the bearings that will lead
to premature failure.
At the end of the storage period follow the
uncrating and start-up procedures. If the unit has
been stored for more than eighteen months contact
the factory before starting the compressor

FREIGHT DAMAGE PROCEDURES

1. The customer, at the receiving point, MUST

inspect each shipment for damage.
2. If the shipment is damaged, the customer
should so note the damage on the freight bill.
3. The customer should request an inspector from
the freight company inspect the equipment
immediately. It is best to send a confirming
letter with the following information.
a. Freight bill number.
b. Date delivered.
c. Shippers name and address.
d. Description of damage (a photograph if
possible).
e. A copy of your invoice for the equipment
4. After inspection (before the inspector leaves).
a. Get a copy of the inspection report.
b. Request the unit be shipped back “free
astray”
c. Request a credit for the original freight bill.

5. Call the factory and:

a. Get a Return Material Authorization (RMA
number).
b. Give a purchase order for repair. The P.O.
should refer to the item and trucker claim.

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SECTION 4

OPERATION

GENERAL

Every Curtis Rotary Screw compressor has been CONSTANT OPERATING MODE (Standard on
prewired for the voltage specified at the time the RS 60 – RS 300)
order was placed. Selecting the CONST position puts the unit into the
on line/off line control mode which allows the motor
The unit has been thoroughly tested at the factory to run continuously while the compressor loads and
to assure it will operate at its rated capacity and is unloads as determined by the high and low settings
in good working order. The user need only to con- of the pressure switch. This mode of operation is
nect the unit to the correct power supply and to the best used in high air demand systems to reduce
compressed air system (and to the appropriate energy consumption.
water supply on water cooled units, refer to
SECTION 3 “INSTALLATION”). MODULATION CONTROL
This control method is accomplished with the same
The purpose of this section is to familiarize the user components as the constant/auto system with the
with the controls, their function and how they addition of a modulation valve and is standard
operate. We strongly suggest that you read and equipment on models R/S 25-R/S 50.
understand this section before starting your See FIGURE 4-6 “Modulation Control”.
compressor.
In the constant operating mode the modulation
OPERATING MODES valve allows the compressor to unload and then
load gradually to meet system air demand. As
The R/S-50D and R/S-50AD models are equipped demand decreases and system pressure increases
with an automatic dual control operating system above the modulation valve low setting, pressure is
consisting of a load/unload control (constant) and a passed to the inlet valve piston, which closes
start-stop control with delay off timer (auto). enough to match the air system demand.
The mode of operation is selected using the switch
marked CONST/AUTO located on the compressor When the system air demand falls below 20% the
control panel. (Ref. Figure 4-1) pressure switch de-energizes the 3-way solenoid
valve. This will activate the blow down valve and
Models R/S-60 thru R/S-300 utilize the constant close the inlet valve allowing the separator to blow
operating mode as standard equipment with start down.
stop control as optional.
When system pressure falls below the low setting
of the pressure switch it will close, energizing the 3-
way solenoid valve which will in turn close the blow
R/S-60 THRU R/S300
OPTIONAL down valve and open the inlet valve to allow the
Hours compressor to pump up to system pressure.

In the AUTO position the compressor utilizes the

R/S-60 THRU R/S300
OPTIONAL same features as constant run but with the auto-
matic start–timed stop control. This operating mode
is best used in applications where air demand
varies widely or there are periods of no demand.
FIGURE 4-1
Control Panel AUTO OPERATING MODE (RS 50D & RS 50AD)
With the selector switch in the AUTO position the
NOTICE motor is allowed to load & unload as dictated by the
For Airtron microprocessor or VFD operation pressure switch. When system pressure reaches
instruction see respective manuals. the high setting of the pressure switch a timer is

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energized which will shut down the unit after a BLOW DOWN VALVE
selected time period (factory set at 10 minutes) if The function of the blow down valve is to relieve
system pressure does not fall to the low setting of the sump pressure when the pressure switch opens
the pressure switch. If the system is allowed to shut at the set operating pressure.
down the amber standby light on the control panel
will illuminate to alert personnel that the unit may While the compressor is loading the valve remains
restart at any time. When the system pressure in the closed position until system pressure is
does fall to the low setting the unit will restart achieved. The 3-way solenoid valve is then de-
turning off the standby light. energized allowing the control air pressure to enter
the “pilot” port opening the valve and allowing
COMPONENT DESCRIPTION pressure from the sump at the “inlet” port to exit
through the “outlet” port to the inlet valve. (Ref.
The components discussed in the “Operating FIGURE 4-3)
Modes” portion of this section along with the other
standard components of the compression cycle are OUTLET
described below to give the user an overview of
their function in the system.

INLET VALVE
This valve controls the loading and unloading of the
compressor in conjunction with the pressure switch
and the 3-way solenoid valve. PILOT AIR
INLET CLOSED POSITION
PRESSURE FROM
The inlet valve, as depicted in FIGURE 4-2, in its FROM SUMP OUTLET
SOLENOID
TANK VALVE
idle position is normally open requiring air pressure
to close (A). On initial start-up the LOAD/UNLOAD
switch located on the control panel (FIGURE 4-1)
should be in the UNLOAD position which closes the
valve to inlet air (B). The valve will remain closed
until the selector switch is switched to the LOAD
position at which time the valve will fully open (C)
allowing the compressor to achieve the maximum OPEN POSITION

air pressure setting of the pressure switch. The

pressure switch then de-energizes the 3-way FIGURE 4-3
solenoid valve allowing control air to close the inlet Blow Down Valve
valve to the unload position (B).

IN IN

OUT OUT

A B
Unload Position Load Position

FIGURE 4-2
Inlet Valve

11
 CAP304

3-WAY SOLENOID VALVE

The R/S Series compressors utilize a 3-way nor-
mally open solenoid valve to provide control air for NOTICE
the load/unload cycle (Ref. FIGURE 4-4). This
valve de-energizes or opens when the maximum Use a light touch when adjusting the modul-
air pressure setting of the pressure switch is ation valve as the metal diaphragm in the
achieved allowing control air to enter the solenoid valve can be damaged if too much pressure
at port #3 and exit at port #2 which connects to the is applied to the adjusting screw.
inlet valve piston and the blow down valve. This
closes the inlet valve to the unload position and
opens the blow down valve to relieve pressure on
the sump. When system pressure is reduced to the
Vent Hole Raise Pressure
low setting of the pressure switch the solenoid
valve will energize or close allowing pressure in the
control lines to exit at exhaust port #1 to the open
OUT
inlet valve.

FIGURE 4-5
Modulation Valve
IN Lower Pressure

MINIMUM PRESSURE VALVE

This is an internally loaded check valve that pre-
vents the back flow of air from system pressure
when the unit stops, unloads or shuts down. The
standard cracking pressure of this valve is
approximately 50 to 80 psi depending on the com-
pressor model. (Ref. FIGURE 4-6)

FIGURE 4-4
3-Way Solenoid Valve

MODULATION VALVE
The function of the modulation valve is to control
the amount of air passed to the inlet valve piston
allowing the compressor to load and unload
gradually as discussed under “MODULATION OUT

CONTROL”.

The modulation valve is set at the factory for

requested pressure at time of order. If working
pressure is changed the valve must be adjusted to
the new pressure setting by turning the screw in the IN

valve dome, clockwise to raise the pressure and

counter-clockwise to lower the pressure. This
adjustment should be made slowly. The pressure
switch settings should be set prior to adjusting the FIGURE 4-6
modulation valve. The modulation valve is set to Minimum Pressure Valve
“weep” air from the vent hole in the valve dome at 8
PSI less than cutout pressure switch setting. The
(Ref. FIG. 4-5)

12
 CAP304

THERMOSTATIC CONTROL VALVE

This valve, located in the oil return line (Ref. FIG- As the oil heats up the thermostat senses the
URE 2-3), incorporates a thermostat to control the temperature and gradually closes the valve to port
temperature of the compressor lubricant. B and opens it to port C through which the heated
oil will flow to the oil cooler before entering the oil
When the compressor is started and the unit is cold filter and compressor. The thermostat is set to
the valve is open to the by-pass at port B allowing maintain a minimum oil temperature of 170° F to
the oil entering at port A to flow directly from the oil prevent moisture contamination in the oil system.
separator through the oil filter to the compressor. (Ref. FIGURE 4-7 & 4-8)

OPEN TO BY-PASS OPEN TO COOLER

PISTON

SLEEVE
THERMOSTAT

BY-PASS
B B
TO COOLER
C C

PORT

A A
SPRING
INLET INLET

FIGURE 4-7
Thermostatic Control Valve
(RS 50D & RS 50AD)

OPEN TO BY-PASS OPEN TO COOLER

TO COOLER

C C

B B
BY-PASS

A A
INLET INLET

FIGURE 4-8
Thermostatic Control Valve
(RS 60D THRU RS 300D)

13
 CAP304

SHUTTLE VALVE
Inlet pilot air from the modulation valve shifts the The pressure switch is set at the factory to the op-
shuttle ball due to zero pressure from the unloader erating range specified when the unit was ordered.
solenoid valve during loaded-modulation operation. The differential is set at 25 psi.
This allows the inlet valve to open and close
according to system CFM demand. The following procedures should be used to set the
control to a new requirement: (Ref. FIGURE 4-10)
In the event the unit reaches unload pressure, the
air from the solenoid valve which is greater than the Operating range adjustment – Turn range adjust-
pilot air from the modulation control valve shifts the ment screw A counterclockwise to lower the upper
shuttle ball closing the pilot air port from the and lower pressure settings. The approximate
modulation valve sending the air pressure to the upper pressure setting is shown on the indicator.
inlet valve piston which in turn closes the inlet valve
plate allowing the unit to fully unload. Differential adjustment – To increase the differ-
(Ref. FIGURE 4-9) ential, turn adjustment screw B counterclockwise.
This will decrease the lower pressure setting only.
TO INLET VALVE
To decrease the differential, turn the adjustment
screw B clockwise. This will raise the lower setting
only.
Note: The use of a pressure gauge is desirable
when setting the control.

FROM
MODULATION
VALVE

TO INLET VALVE

FROM
SOLENOID
VALVE

FIGURE 4-9
Shuttle Valve

PRESSURE SWITCH FIGURE 4-10

In operation a low friction, straight in-line mech- Pressure Switch
anism operates a snap action switch at a
predetermined pressure setting. An increase in
pressure causes the normally closed circuit to open
and the normally open circuit to close. This is
known as the “trip” pressure. When the pressure
returns to a lower predetermined setting, the circuit
will reset. This is known as the ”reset” pressure.
The difference between the “trip” and ”reset”
pressure is known as the differential.

14
 CAP304

INITIAL START-UP

After completing the initial start-up checks, as

noted in SECTION 3 “INSTALLATION”, the
machine is ready to start. Turn the switch marked
UNLOAD /LOAD to the unload position then press
the START button. When the unit reaches full
speed, turn the UNLOAD/LOAD switch to the load
position (Ref. FIGURE 4-1). The minimum pressure
valve will allow 60-65 PSI to build in the air/oil
separator before releasing down stream.

Watch the following measurements carefully at the

instrument panel while the compressor is running:

1. Compressor discharge temperature should

range between 160° to 180° F when running at
full speed.

2. Separator tank pressure should not be more

than 3-5 PSI higher than the system pressure.

SHUTTING DOWN THE COMPRESSOR

Before shutting down the compressor, turn the

UNLOAD/LOAD switch to unload and allow the
separator tank time to blow down for 45 to 60
seconds. When the separator tank pressure gauge
reads 20-30 PSIG press the Stop button to turn off
the compressor.

Failure to follow this procedure when

shutting down the compressor will lead to oil
carry over.

15
 Pressure
Pressure Regulator Solenoid
Switch For 175 psi Unit Valve

Air Blow Down

Valve
Air
Air
Minimum Air
Pressure Modulating
Valve Valve
Air Air
Inlet
System Sight
Pressure Glass Outlet Filter
Gage
Safety Pilot
Air Valve
Check
Shuttle Inlet Valve
Temperature Valve Valve
Oil Switch
Air
Air End
Orifice Check
Valve

Separator Oil

16
Separator Pressure
Tank Oil Level Gage
ASP Oil
Air Oil Separator Switch Temperature
Element Gage
Cooler Cooler Scavenger Temperature
Oil Switch
Line
Air/Oil

Oil Filter Shutoff Valve

Air Drain Line
Discharge Oil

Thermostatic
Control
Valve Oil

Figure 4-11
Flow Diagram
Modulation Control
CAP304
 CAP304

SECTION 5

MAINTENANCE

GENERAL

Your Curtis rotary screw compressor has been Heavy- duty air filter replacement (Figure 5-1)
designed to require a minimum amount of
maintenance. However, as with any piece of 1. Clean the exterior surfaces of the filter canister.
mechanical equipment, the implementation of a 2. Loosen the wing nut and remove the filter
good maintenance program is recommended for cover.
smooth day-to-day operation of your compressor 3. The heavy-duty filter consists of two elements,
and for the longevity of your compressed air a main element with a safety element inside.
system. Remove the safety element from inside the
main element then the main element from the
This section will provide the user with instructions filter body.
for maintenance and/or replacement of the ser- 4. Using a damp cloth clean the interior surfaces
viceable components. of the filter body and cover. Do not attempt to
blow dirt out with compressed air.
NOTE: Some components of your unit may be 5. Inspect and/or replace the elements.
equipped with service indicators that alert the user 6. Replace the cover and tighten the wing nut.
when service on these items is required. 7. Reset the maintenance indicator if applicable.

MAIN
ELEMENT*
BODY
Before performing any maintenance be sure
the electrical supply has been cut off, locked
and tagged and that all pressure has been
relieved from the compressed air system.

AIR FILTER
WING NUT
Frequency of servicing the air filter will depend on
the environmental conditions under which the
compressor is operating. Service the air filter
element under any of the following conditions which
ever comes first.

• Check the air filter element weekly and change COVER

if outside surface of the element appears to be
coated with dust.
SAFETY
• Change every two thousand (2000) hours of ELEMENT*

operation or every six (6) months.

• Under unusually dirty ambient conditions

change the element as required. *Consult appropriate parts list for element part
numbers
• When service indicator or differential pressure
gauge reads 15”, service is required. Figure 5-1

17
 CAP304
Air filter inspection and cleaning

It is recommended that the air filter elements be 1. Shut down the unit.
changed every six (6) months or 2000 hours. 2. Wait one (1) minute after the compressor stops
However the filter element(s) should be inspected to allow the pressure to be relieved and the
and cleaned if necessary on a weekly basis in lubricant to settle.
conjunction with your maintenance program. 3. Observe the lubricant level. It should be at the
Instructions for inspecting the element(s) are as center of the sight glass.
follows: 4. To add lubricant, disconnect the power, lockout
and tag to prevent accidental restarting.
1. Shine a bright light through the element from 5. Clean dirt from around the fill cap.
the inside to inspect for damage. If cracks or 6. Loosen the cap and make sure any additional
pinholes are detected discard the element. pressure is relieved through the vent hole, then
2. If elements appear in good condition return remove.
them to the filter housing per previous filter 7. Add lubricant to the proper level.
replacement instructions. 8. Replace cap and tighten securely.

LUBRICANT

Your compressor has been tested and shipped with

a full charge of CURTIS LUBEPLUS RS-8000
synthetic oil. This lubricant has been specially form- Do not attempt to remove the fill cap, drain
ulated to extend the service life of your comp- plug or any other components while the
ressor and is advantageous for high temperature compressor is running or pressurized.
operation, easy start-up when cold, reduced sludge
and lacquer buildup and is completely compatible
with all seals, gaskets and other compressor
materials.

Change the lubricant as noted in the “Maintenance

Schedule” located on page 25 of this manual.
Between changes check the oil level daily and add
as necessary.
FILL CAP
When operating in severe conditions it will be
necessary to change the lubricant more frequently.
Temperature of operation has the most significant SIGHT GLASS
effect on the life of the lubricant. The following chart
shows the decrease in interval based on
temperature.

Discharge Temperature RS-8000 DRAIN VALVE

Up to 180° F 8000 Hrs.
180° to 190° F 6000 Hrs.
190° to 200° F 4000 Hrs. DRAIN PLUG
200° to 210° F 2000 Hrs.

Hot oil under pressure can cause severe Figure 5-2

injury, death and/or property damage. Be sure
the compressor is shutdown and the pressure Changing lubricant (Ref. Fig. 5-2)
is relieved before attempting to change or add
lubricant. 1. Shut down the unit; disconnect the power,
lockout and tag to prevent accidental restarting.
2. Wait one (1) minute after the compressor stops
Checking level and adding compressor oil. (Ref. to allow the pressure to be relieved.
Fig. 5-2)

18
 CAP304
3. Clean the dirt from around the fill plug. 5. Apply a light film of the compressor oil to the
4. Loosen the fill plug and make sure any gasket surface on the new element.
additional pressure is relieved through the vent 6. Hand tighten the new element until the gasket
hole, then remove. is seated in the gasket groove.
5. Remove the drain plug from the end of the 7. Continue tightening the element by hand an
drain line at the bottom of the separator tank. additional ½ to ¾ turn.
6. Open the ball valve and allow the oil to drain. 8. Restart the unit and check for leaks.
7. When the oil has completely drained close the
ball valve and replace the drain plug.
8. Refill with CURTIS LUBEPLUS R/S 8000 FILTER HEAD
Compressor lubricant. (Consult the spec- (W/ BY-PASS)
SET 25 PSI
ifications section for the proper amount of
lubricant for your model).
9. Replace the fill cap and tighten securely.
10. Restart the unit and allow the lubricant to
GASKET
circulate through the system.
11. Shutdown the unit and follow the steps for
checking the oil level.
FILTER
ELEMENT*

Over filling the oil reservoir can cause oil

carryover and damage the compressor. Do
not fill above the full mark in the sight
glass.

Mixing lubricants can damage the

compressor and will void the warranty. Use *Consult appropriate parts list for correct element
only CURTIS lubricants. part number.
Figure 5-3

Oil filter replacement NOTE: R/S200 and above utilize double element
spin on filter heads. Change both per above
Change the oil filter element after the first one instructions.
hundred (100) hours of operation. Then under any
of the following conditions: SEPARATOR ELEMENT

• Every six (6) months or one thousand (1000) The air/oil separator element never “wears out” but
hours whichever occurs first, it does lose its effectiveness due to being plugged
• Every lubricant change with dirt. To obtain long separator life, it is
• As indicated by the maintenance indicator. important to change the air inlet filter and the
lubricant filter as suggested in the maintenance
Change as follows: (Ref. Fig. 5-3) schedule.

1. Shut down the unit; disconnect the power, Change the separator element under any of the
lockout and tag to prevent accidental restarting. following conditions, whichever comes first:
2. Wait one (1) minute after the compressor stops • Whenever pressure drop between system and
to allow for the pressure to be relieved. separator exceeds 10 PSI.
3. Using a strap wrench remove the old filter from • Once a year.
the filter head. • Every four thousand (4000) hours.
4. Clean the gasket contact surface on the inside • When excessive oil appears in the air dis-
of the filter head. charge line.
• As indicated by the maintenance indicator

19
 CAP304

SIGHT GLASS
Separator element replacement (Ref. Fig. 5-4) ORIFICE

1. Shut down the unit; disconnect the power,

lockout and tag to prevent accidental restart. SCAVENGER TUBE
2. Allow one (1) minute after the compressor
stops to allow the pressure to be relieved and
COVER BOLT
the oil in the sump to settle.” COVER
3. Disconnect the main airline and the scavenger
tube from the separator cover.
4. Disconnect the control airlines after noting their
connection points. Tag the lines if necessary.
5. Use a suitable wrench and remove the bolts ELEMENT*
that hold the separator cover and lift the cover
from the separator tank.
6. Lift the element up and out of the separator
tank and discard. SEPARATOR
TANK
7. Carefully lower the new element into the
separator tank and center.
8. Clean and replace the cover, align the holes
and install the bolts. Tighten the bolts in a cross
pattern to prevent over tightening one side of
the cover (See bolt torque specifications).
9. Install the main airline and the control airlines.
10. Install the scavenger tube making sure the end
is touching the bottom of the separator
element.
11. Clean the orifice located at the end of the
scavenger tube where it enters the inlet valve
or air end. *Consult appropriate parts list for element part no.
12. Reconnect the power, restart the unit and Figure 5-4
check for leaks.

THERMOSTATIC CONTROL VALVE

In normal operation the thermal by-pass valve

Separator, piping and control lines may be controls the oil temperature and prevents moisture
very hot immediately after shut down. Allow contamination of the oil. Malfunction of this valve
the unit to cool before attempting service. may result in moisture in the oil system that can
damage the compressor and cause oil carry-over.
A failure of the element in the closed position will
divert the lubricant from the oil cooler and result in
SCAVENGER LINE OIL SIGHT GLASS the unit shutting down due to high temperature.

A repair kit is available for this valve to replace the

During loaded operation there should be a visible wearable components. Consult the parts list for
mist of lubricant in the sight glass. If no flow is your compressor to obtain the part number for this
visible then the orifice is blocked or restricted. The repair kit.
orifice is located in the scavenger line were it
enters the inlet valve or air end. (Ref. Figure 5-4)

NOTE: After installation of a new separator

Before performing any maintenance be sure
element, lubricant will not necessarily appear in the
the electrical supply has been cut off, locked
sight glass for the first several hours of operation.
and tagged and that all pressure has been
If clogging is suspected remove the orifice and
relieved from the compressor system.
clean in a suitable solvent.

20
 CAP304
Thermostatic Control Valve Repair (R/S 50D & Thermostatic Control Valve Repair (R/S 60D
R/S 50AD) (Ref. Fig. 5-5) thru R/S 300D) (Ref. Fig. 5-6)

1. Place a spill pan under the valve. 1. Place a spill pan under the valve
2. Remove the snap ring from the top of the valve 2. Disconnect lines from cooler and sump and
body. The valve is spring loaded and the cap remove valve from the system.
may pop up when the ring is removed. 3. Loosen the 4 bolts and washers and separate
3. Remove the cap and internal parts taking care the lower body from the upper body.
note the orientation of the spring, piston and 4. Remove thermostat lip seal and “O” ring from
element. the upper body.
4. Reassemble with the renewal parts. Take care 5. Reassemble with renewal parts. Make sure the
when replacing the cap not to cut the “O” ring “O” ring is properly seated in recess in the
or put undue stress on the attached piping. upper body.
5. Replace any lost lubricant. 6. Replace valve in system and reconnect the
6. Return the unit to service. cooler and sump lines.
7. Replace any lost lubricant.
8. Return unit to service.

SNAP RING
UPPER BODY
CAP

O RING
LIP SEAL

THERMOSTAT
PISTON
W/ ELEMENT

O-RING
SLEEVE

LOWER BODY

SPRING
WASHER
BOLT
BODY

Figure 5-6

MINIMUM PRESSURE VALVE

The minimum pressure valve is a non-adjustable

Figure 5-5 spring loaded check valve designed to maintain
approximately 65 psi in the separator tank and
prevent the backflow of air from the system to the
separator.

Air exiting the vent hole in the cap indicates “O”

ring failure-allowing air to leak into the spring cavity
inside the cap, which will effect the operation of the
valve.

21
 CAP304

Consult the appropriate parts list kit available to

repair this valve, depicted in Figure 5-7, as follows.

1. Carefully unscrew the spring loaded valve cap. Before performing any maintenance be sure
2. Remove the piston and seat assembly. the electrical supply has been cut off, locked
3. Inspect the valve body for scratches and and tagged and that all pressure has been
deterioration of the seating surfaces. relieved from the compressed air system.
4. Replace the “O” ring on the piston taking care
not to damage it.
5. Reassemble the piston with the new seat FAN
assembly and spring and replace in the valve
body. Check the fan for cracking, loose screws, and loose
6. Replace the spring and tighten the cap. blades. Make sure that it is securely mounted to the
7. Return the unit to service shaft. Tighten the mounting screws if loose.
Replace a damaged fan immediately.

CAP
INLET VALVE

The inlet valve opens and closes in relation to the

air demand. A malfunction of this valve will affect
SPRING the capacity control system. The inner assembly
should be checked periodically for wear on its
replaceable components. Replacement or these
O RING components is recommended after twelve thou-
sand (12,000) hours of operation. Repair kits are
available from your authorized Curtis distributor.

PISTON Inlet valve repair (R/S 50AD)

(Ref. Figure 5-8)
CV SPRING
1. Shut down the unit; disconnect the power,
lockout and tag to prevent accidental restarting.
CV ASSEMBLY
2. Wait one (1) minute after the compressor stops
to allow the pressure to be relieved.
3. Remove the inlet filter assembly.
4. Remove the snap ring, “O” ring, cv assembly
and spring.
5. Unscrew the piston cap and remove the piston
BODY and spring.
6. Carefully replace the “O” ring on the piston.
7. Reinstall the piston in the valve body along with
the new piston spring taking care not to
damage the “O” ring.
8. Re-seat and tighten the piston cap.
9. Replace the cv spring and re-seat the cv
assembly.
10. Carefully install the new “O” ring and secure
the complete assembly with the upper snap
ring.
Figure 5-7 11. Re-install the air filter assembly.

22
 CAP304

SNAP RING CAP

OUTER RETAINING RING
"O" RING
SPRING "O" RING
CV ASSEMBLY

CV ASSEMBLY
PISTON
CV SPRING CV SPRING
"O" RING
INNER RETAINING RING

CAP
BODY

INNER SPRING

OUTER SPRING

PISTON

Figure 5-8 "O" RING

BODY

Inlet valve repair (R/S 50D thru R/S 200D)

(Ref. Figure 5-9)

1. Shut down the unit; disconnect the power,

lockout and tag to prevent accidental
restarting.
2. Wait one (1) minute after the compressor
stops to allow the pressure to be relieved.
3. Remove the inlet filter assembly. Figure 5-9
4. Remove the outer retaining ring, “o” ring, cv
assembly and cv spring.
5. Remove the inner retaining ring, cap and
inner and outer spring and piston.
6. Replace the inner and outer springs and
piston “o” ring and re-install them in the valve. Air/Oil COOLER (Air Cooled Models)
7. Replace the cap and secure with the inner
retaining ring. The air/oil cooler fins MUST be cleaned period-
8. Replace the cv spring and re-install the cv ically. Frequency of cleaning depends on sur-
assembly. roundings and environmental conditions. Dirt and
9. Carefully install the new “o” ring and secure dust buildup on the cooling fins will cause a
the complete assembly with the outer decrease in thermal efficiency and cooling capacity.
retaining ring. This will ultimately lead to overheating and potential
10. Re-install the air filter assembly. compressor failure.

23
 CAP304

DRIVE SYSTEM

Routine examination of the drive system is 6. Slide the motor flange into position on the
recommended to insure maximum compressor life. sleeve and using the dimension shown in
Check the drive coupling periodically for wear. We Figure 5-11 set the gap between the flanges.
recommend the coupling be replaced at 12,000 The flanges will extend about 1/16” over the
hours of operation. teeth. Note: Do not bottom flange against
coupling element, leave 1/16” clearance.
7. Apply Loctite 242 and tighten the setscrew on
the motor flange.
Do not operate the compressor with the 8. Re-install the coupling guard and securely
coupling guard removed. Exposed coupling tighten the 4 bolts holding it to the motor base.
can cause injury to personnel 9. Return the unit to service.

Coupling Replacement (Ref. Figure 5-10)

1. Disconnect the power and relieve all pressure

to the system.
2. Remove the coupling guard held to the motor
base by 4 bolts.
3. Loosen the setscrew on the motor flange and
pry the flange away from the coupling sleeve.
4. Remove the wire retaining ring holding the two-
piece coupling sleeve. It may be necessary to
pry the ring loose with a blunt screw driver
5. Remove worn sleeve and replace with the new
sleeve and force the retaining ring into its
groove in the center of the sleeve. Again it may
be necessary to pry the ring into position with a
blunt screwdriver.
Figure 5-11

COUPLING GUARD

MOTOR FLANGE

COUPLING SLEEVE

AIR END FLANGE

RETAINING RING

Figure 5-10

24
 CAP 304

RS Series (50 hp – 300 hp) MAINTENANCE SCHEDULE*

SERVICE INTERVALS (HOURS)

WEEKLY

YEARLY

EVERY

10 000

12 000

14 000

16 000

18 000

20 000

22 000

24 000
DAILY

2 000

4 000

6 000

8 000
500
DESCRIPTION PART No QTY

Check sump oil level (fill if necessary) y

Check oil scavenger line for oil flow y
Check/clean scavenger line orifice y y y y y y
Check pressure safety valve for operation3 y
Check load/unload cycle; Check all electrical connections y y y y y y y y y y y y
Drain condensate from air receiver y y y y y y y
Inspect air inlet filter element; check hose(s) for wear4 y
Check belt tension / alignment y5 y
Check/clean finned heat exchangers y
Check for loose fittings and fasteners y
Drain condensate from separator tank y
Change oil filter y1
Oil sample VO701-POL y1 y y y y y y
RS50D VGA713
RS60D, RSD-75 VGA716
RSD-100 VGA720
2000 HR Service Kit y y y y y y
RS125D, RS150D VGA723
RS200D VGA726
RS250D, RS300D VGA729
RS50D VGA714
RS-60D, RSD-75 VGA717
RSD-100 VGA721
4000 HR Service Kit RS125D, RS150D VGA724 y y y
RS200D VGA727
RS250D VGA730
RS300D VGA732
RS50D VGA713
RS60D, RSD-75 VGA716
RSD-100 VGA720
6000 HR Service Kit y y y
RS125D, RS150D VGA723
RS200D VGA726
RS250D, RS300D VGA729
RS50D VGA715
RS60D VGA718
RSD-75 VGA719
RSD-100 VGA722
8000 HR Service Kit y y y
RS125D, RS150D VGA725
RS200D VGA728
RS250D VGA731
RS300D VGA733
Change lubricant2 RS50D 8 USG
FSC-MaxFluid RS60D, RSD-75, RSD-100 15 USG
RS125D, RS150D FSC-8000 25 USG y y y y
RS200D 40 USG
RS250D, RS300D 50 USG

Notes:
1) Initial 500 h or 30 days; whichever occurs first. Follow regular intervals thereafter.
2) Change oil yearly if operating under 8000 h. Lubricant may require more frequent changes depending on operating environment and running conditions.
3) Do not tamper with safety valve setting - it is factory set - only check operation! Tampering will void warranty and result may cause severe injury or death.
4) Replace as necessary or every 5 years.
5) Initial check for proper tensioning @ 100 h. Follow regular 500 h interval thereafter.
* The maintenance intervals described herein are for normal operating condition in clean and well ventilated environments. Frequency of intervals will increase for non-standard environments. Please contact your authorized FSCURTIS distributor
for more information and recommendations.
Service Kits:
2000 and 6000 Hour Kit: inlet air filter + oil-filter, 4000 Hour Kit: inlet air filter + oil-filter + air/oil separator, 8000 Hour Kit: inlet air filter + oil-filter + air/oil separator + inlet valve. kit + thermo-valve kit + min. pres. valve. kit.

25
 CAP304
TROUBLESHOOTING
Symptom Probable Cause Remedy
Failure to start Power not turned on. Turn power on by connecting main
disconnect switch or circuit breaker.

Blown main circuit fuse. Replace fuse.

Blown control circuit fuse. Replace fuse.

Safety circuit shutdown-high Correct situation per remedy described

discharge temperature under “High Discharge Air Temperature”
symptom of this troubleshooting guide,
then press the manual reset button on
the high discharge temperature switch,
restart compressor.

Overloaded motor, thermal Press reset button on motor starter.

overload, Relay tripping.

Unscheduled shut down High discharge temperature. Correct situation per remedy described
under “High Discharge Air Temperature”
symptom of this troubleshooting guide,
then press the manual reset button on
the high discharge temperature switch,
restart compressor.

Overloaded motor, Thermal Press reset button on motor starter.

Overload relay tripping.

Low receiver pressure Excessive air demand Re-evaluate air demand.

Excessive leaks in service lines. Repair service lines.

Inlet valve not fully open. Correct situation as per remedy described in
“Malfunctions in the capacity system” (A) “Inlet
valve not opening or closing in relation to air
demand” section of this troubleshooting guide.

Dirty inlet air filter. Clean air filter element or replace with a
new element.

Air pressure switch not set Readjust air pressure switch to desired cut-in
Correctly. and cutout pressure.

Faulty receiver pressure gauge. Check and replace if found faulty.

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TROUBLESHOOTING (CON’T.)

Symptom Probable Cause Remedy

High discharge air Not enough cooling water flowing Check water system for possible
temperature through the cooler (water cooled restriction, including water regulator
models). valve.

Inadequate circulation of cooling air at Check location of cooler to make sure

cooler (air cooled models). there is no restriction to free circulation of
cooling air. Also check the fins of the
cooler and if found dust laden, clean with
compressed air while the machine is not
running.

Low oil level in separator. Add oil and bring to recommended level.
Also check oil system for possible leaks.

Dirty oil filter. Replace oil filter element.

Low air delivery
Dirty air filter. Clean air filter element(s) or replace with
new element(s).

Excessive leaks in service line. Repair service lines.

Inlet valve not opening completely. Correct situation per remedy described
under “Malfunctions in the capacity
control system” – (A) “Inlet valve not
opening or closing in relation to air
demand” section of this trouble shooting
guide.
Safety valve blows
Air pressure switch not set correctly. Readjust pressure switch so that the
compressor unloads at the desired
pressure.

Inlet valve not closing properly in Correct situation per remedy described
relation to air demand. under “Malfunctions in the capacity
control system” – (A) “ Inlet valve not
opening or closing in relation to air
demand” section of this trouble-shooting
guide.

Dirty separator. Replace with new air/oil separator

element.

Faulty receiver pressure gauge. Check gauge for accuracy.

Faulty safety valve. Check safety valve for correct pressure

setting. Replace valve if leaking.
Excessive oil
consumption Separator tank overfilled. Drain oil in separator to full mark on oil
level gauge.

Blocked scavenger line. Clean scavenger line and orifice.

Faulty oil filter. Replace oil filter element.

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TROUBLESHOOTING (CON’T.)

Symptom Probable Cause Remedy

Oil breakdown. Correct situation per remedy described in
“Oil breakdown” section of this
troubleshooting guide.

Wrong oil being used. Refer to SPECIFICATIONS section of

this manual for correct oil.

Rapid start/stop or load/unload cycle. Correct situation per remedy described in

“Malfunctions in the capacity control
system” - (C) “Rapid cycling” section of
this troubleshooting guide.

Excessive oil foaming. Same as above.

Scavenger line does not extend to Check scavenger line connections on

bottom of separator. separator tank.

Operating pressure to low. Receiver pressure should not drop below

100 PSIG when running loaded. Leak in
system or air consumption is too great.

Faulty or damaged separator element. Change air/oil separator.

Leak in oil line. Check for leaks and correct.

Shaft seal failure. Replace necessary components of the

seal or complete seal if necessary.

Rapid pressure loss in system. Look for applications using large

amounts of air very quickly. An air
receiver should be installed in the
system.

Starting the unit before the separator Change procedure and instruct operators
has been blown down. on proper use.

Frequent air filter Faulty air filter or inadequate filter for Replace faulty air filter element. If air
clogging the environment. filter is inadequate replace it with a
heavy-duty air filter.

Oil breakdown Extreme operating conditions such as Operate compressor at recommended

high oil injection and compressor receiver pressure and oil injection
discharge temperatures, high ambient temperature.
temperature with high humidity and
high receiver pressure.

Contaminated oil. Service air filter element and oil filter

element in accordance with maintenance
schedule.

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TROUBLESHOOTING (CON’T.)
Symptom Probable Cause Remedy

Negligence in draining condensate Drain condensate from the separator

from the separator. periodically. More frequent draining might
be necessary when operating at high
ambient temperature and high humidity
environment.

Mixing of different brands of oil. DO NOT MIX DIFFERENT BRANDS OF

OIL.

Wrong type of oil being used. Refer to SPECIFICATIONS section of this

manual for correct oil.
Malfunctions in the
capacity control system

(A) Inlet valve not Improper setting of the air pressure Readjust air pressure switch to proper
opening or closing in switch or faulty switch. setting. Replace if faulty.
relation to air
demand.
Faulty unloader solenoid valve. Replace solenoid valve.

Jammed inlet valve. Check inlet valve assembly.

Pressure regulator set to low. Adjust pressure regulator to 100 PSI

minimum (175 PSI units).

Readjust air pressure switch setting.

(B) Compressor does Air pressure switch not set correctly.
not unload when
there is no air Check wiring and solenoid valve.
demand. Faulty solenoid valve.
Replace air pressure switch.
Faulty air pressure switch.
Repair leaks.
Leaks in service lines.
Provide sufficient volume by adding air
receiver.
(C) Rapid Too small volume of air in service
cycling between line. Add larger compressor, check system for
Load and Unload air leaks
Using too much air.
Readjust cut-in and cutout pressure
settings.
Cut-in cutout pressure set too close in
pressure switch. Inspect valve. If necessary, replace.

Bring the oil to recommended level by

Oil coming out through Faulty inlet valve. draining the separator. Use the oil level
air filter at shutdown gauge as a guide.

Oil coming out through Oil level too high in separator. Correct situation as per solutions described
blow down valve under “MALFUNCTIONS IN THE
CAPACITY CONTROL SYSTEM” – “(C)
Cycling too often between load and Too rapid cycling between load and
unload. unload” section of this guide.

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SECTION 6

SPECIFICATIONS

ENGINEERING DATA
R/SD R/SD R/SD R/SD R/SD R/SD R/SD R/SD R/SD
MODEL
50 60 75 100 125 150 200 250 300
OIL(GAL.)
8 15 15 15 25 25 40 50 50
CAPACITY
AIR (IN.)
1½ 1½ 2 2 2 2 2½ 3 3
CONNECTION
OIL G.P.M. 20 25 28 32 46 50 55 65 90
MOTOR RPM 1750 3500 1450 3500 1750 1750 1750* 1750 1750
BTU/M
2000 2100 2900 3850 4900 5860 7500 9400 11250
OIL COOLER
BTU/M
300 400 550 750 915 1100 1500 1850 2200
AFTERCOOLER
COOLING
8000 9500 12500 16000 18000 22500 22500 28000 28000
FAN CFM
MOTOR
6 5 5 4 3 3 3 2 2
STARTS/HR MAX

SUBJECT TO CHANGE WITHOUT NOTICE

*MOTOR RPM 3500 ON NON-GEARED MODEL

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 CAP304
DIMENSIONAL DATA

WT. WT.LESS
R/S-D A B C
ENCL. ENCL.
HP CFM / PSI* AIR OUT
MODEL IN. IN. IN. LBS. LBS. -- 100 125 150 175 NPT
R/S50-D 42 72 44 2130 1925 50 240 222 195 165 1 1/2”
R/S60-D 48 76 60 2570 2170 60 280 275 236 212 1 1/2”
R/S75-D 54 84 60 3140 2690 75 365 329 305 270 2”
R/S100-D 54 84 60 3400 2950 100 465 458 363 340 2”
R/S125-D 66 84 64 5320 4520 125 600 570 516 440 2”
R/S150-D 66 84 64 5550 4750 150 760 706 583 546 2”
R/S200-D 70 90 64 5850 5150 200 960 860 770 680 2 1/2”
R/S250-D 75 96 78 9500 8800 250 1170 1073 970 N/A 3”
R/S300-D 75 96 78 9800 9100 300 1450 1298 1150 N/A 3”

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Recommended Bolt HHCS Torque Specification*

HHCS
Tightening Torque
SAE 5
¼-20UNC 10 ft-lbs
5/16-18UNC 21 ft-lbs
3/8-16UNC 37 ft-lbs
½-13UNC 90 ft-lbs
5/8-11UNC 180 ft-lbs
*Note: these values are for stiff metal-to-metal joints when SAE 10 oil is used as lubricant.

Separator Tank Lid Bolt Torque Specifications

SEPARATOR BOLT
UNIT USED BOLT SIZE
TANK TORQUE
ON AND QUANTITY
NUMBER (FT-LBS.)
RN10222-2 R/S 50D, 50AD 5/8”-11 (8) 80
RN10223 R/S 60D-100D ¾”-10 (8) 80
RN10224-1 R/S 125D, 150D 7/8”-9 (8) 80
RN10226 R/S 200D 1”-8 (8) 80

Bolt Torque Sequence

1 3

8 5

6 7

4 2

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 CAP304

COMPRESSOR MAINTENANCE LOG

MODEL SERIAL NUMBER

REFER TO THE COMPRESSOR INSTRUCTION MANUAL FOR COMPLETE MAINTENANCE

INFORMATION AND SCHEDULE. THE COMPRESSOR INSTRUMENT PANEL LISTS A BRIEF
MAINTENANCE OUTLINE
DO NOT REMOVE LOG FROM THIS UNIT

Record date in Date Column and hourmeter reading in the column under each item on which maintenance
is performed. Record pressure differential gauge readings when any other maintenance is performed to
provide running record of approaching oil filter of separator change.

OIL COOLER CLEANED

PRESSURE DROP OIL OIL
AIR FILTER OIL HEAT
DATE FILTER SEPARATOR RADIATOR EXCHANGER
OIL OIL CHANGED
CHANGED CHANGED CORE TUBES
CLEANED CHANGED FILTER SEPARATOR

37
 CURTIS-TOLEDO, INC.
1905 Kienlen Avenue / St. Louis, Missouri 63133
(314) 383-1300 / Fax (314) 381-1439
info@curtistoledo.com
website: www.curtistoledo.;com

Sales representatives in principal cities.