Acv Automatic Control Valves PDF
Acv Automatic Control Valves PDF
Acv Automatic Control Valves PDF
ACV
AUTOMATIC CONTROL VALVES
ACV
AUTOMATIC CONTROL VALVES
Sierra automatic control valves ACV SCOPE OF SUPPLY
are hydraulically operated pilot
NOMINAL DIAMETER: DN50 - DN1000
actuated globe valves that are
PRESSURE RATINGS: PN10, PN16, PN25
used to control pressure, flow
TEMPERATURE RANGE: +1°C to +65°C
or level in water and irrigation
DESIGN: EN1074-5
networks
FLANGE DIMENSIONS: EN1092-2, ISO7005-2
Sierra ACVs consist of the
TIGHTNESS CHECK: EN12266, ISO5208
main valve (Globe valve) and
a hydraulically operated pilot
(actuator) that functions using ACV FIELDS OF APPLICATIONS
the hydraulic energy of the fluid
PRESSURE, FLOW, LEVEL, AND PUMP CONTROL
thus ensuring independence
IN THE FOLLOWING FIELDS:
and reliability of the equipment
We encourage you to consult
• Water pipelines and distribution networks
Sierra representatives when
• Irrigation pipelines and networks
you have any questions. Our
• Ground reservoirs and elevated tanks
experienced engineers will help
• Pumping Stations
you identify the right solution for
• Water hammer systems
your application.
• Water treatment plants
3
OPERATING PRINCIPALS
FOR AUTOMATIC CONTROL VALVES
IN ORDER TO EXPLAIN HOW AN ACV WORKS THE FIRST STEP
IS TO SHOW AN ACV OPERATING AS AN ON/OFF VALVE.
THEN THE OPERATING PRINCIPAL OF THE MODULATING FUNCTION IS EXPLAINED.
ACV OPERATIONS
A) Operating principle ON/OFF function
1) Valve closing
When the isolation valve at the inlet of the pilot
system is open it will allow flow from the upstream to
fill the valve bonnet. When the isolation valve at the
downstream is closed flow will be trapped inside the
bonnet and the main valve disc will be forced to close
(inlet valve open / outlet valve closed).
2) Valve opening
When the isolation valve at the inlet of the pilot
system is closed it will prevent flow from the upstream
to fill the valve bonnet. When the isolation valve at
the downstream is open the trapped water inside the
bonnet will be released allowing the main valve disc
to open.
4
1) Single Function Operation
• Valve closed
When the pilot closes water is trapped inside the
bonnet and the main valve disc will be forced to close.
• Valve Opened
When the pilot opens water is released from the
bonnet allowing the main vave disc to open.
• Valve Modulating
The main valve will mimic the small pilot valve. When
the latter partailly closes the main valve does the same
and vice versa.
2) Multifunction Function operation
5
ACV
AUTOMATIC CONTROL VALVES
MAIN VALVE COMPONENTS AND DIMENSIONS
25 2
24 22
21 26
20 10
7 15
19 14
16 23
18 4
17 3
12 11
5 6
8 13
1 9
7
SIERRA MAIN BODY AND PILOT SYSTEM
Sierra’s main valve consists of 3 parts; body, Cover
and mobile unit assembly (disc, diaphragm, retainers,
and stem) which are all made in ductile cast iron to
guaranty an improved strength to weight ratio, greater
ductility, toughness, and wear resistance. All parts
are epoxy powder coated with minimum thickness of
250microns to protect the valve from corrosion.
MOBILE UNIT
8
A) Optional DesiGN Features for Body
3- Limit switches
The main valve can be equipped with two limit
switches giving a remote signal showing if the valve is
either open or closed.
9
DIMENSIONS OF AUTOMATIC CONTROL VALVES
Dp
H1
H2
10
ACV
AUTOMATIC CONTROL VALVES
ENGINEERING DATA
FLOW CHARACTERISTICS
The flow characteristic of a valve is the relationship 100
between the position of the disc and the rate of 90
flow through the valve. Each valve has its own flow
80
coefficient (also known as Kv value).
OPENING PERCENTAGE %
70
For best performance Control Valves should 60
be operating at 15% - 75% of stem valve travel
50
(shown on the Y-axis between the 2 dotted lines),
which is approximately 5% - 80% of Kv values. 40
30
At a degree of opening less than 15% the valve
is probably oversized and is subjected to severe 20
VELOCITY LIMITS
The maximum allowable continuous velocity through an ACV varies depending on the required func-
tion and the available head loss. For more details on this topic please refer to the data sheet section of
the required function.
The maximum allowable continuous velocity should not exceed 4m/sec at the valve flange.
The minimum allowable continuous velocity should not be less than 0.4m/sec at the valve flange.
Under free opening condition the head loss caused by the valve is around 5meters. Once the velocity
reaches 2m/sec (under free opening condition) the valve is fully open and acts as an orifice, hence the
head loss is calculated using the following equation:
ΔH= K*(V²/2G)
ΔH =HEAD LOSS (M)
V=AVERAGE VELOCITY (M/SEC)
K =RESISTANCE COEFFICIENT
DN 50 80 100 150 200 250 300 350 400 500 600 700 800 1000
KV 49 62 130 203 458 683 1272 1430 1831 3256 3256 5087 5502 9400
K 9 19.8 11.3 15.2 12.3 16.4 11.5 12.2 12.8 10.8 20 18.3 13.7 19.6
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CONTROL VALVES SIZING & CAVITATION
Control valves are not sized to the pipeline diameter but in accordance with the application and the
maximum and minimum flow conditions. Maximum and Minimum Flow rates as well as downstream
and upstream pressures are required to determine the correct valve size.
Cavitation
Cavitation can occur in valves when used in modulating service. Cavitation is the sudden vaporization
and condensation of a liquid downstream of the valve due to localized low pressure zones. When flow
passes through a throttled valve, a localized low pressure zone forms immediately downstream of
the valve. If the localized pressure falls below the vapor pressure of the fluid, the liquid vaporizes and
forms a vapor pocket. As the vapor bubbles flow downstream, the pressure recovers, and the bubbles
violently implode causing a popping or rumbling sound similar to tumbling rocks in a pipe. The
sound of cavitation in a pipeline is unmistakable. The condensation of the bubbles not only produces
a ringing sound, but also creates localized stresses in the pipe walls and valve body that can cause
severe pitting.
Cavitation Chart:
Use the cavitation charts in the table below to determine whether the valve subjected to cavitation
ALWAYS TRY TO BE IN THE CAVITATION SAVE ZONE (NORMAL WORKING CONDITION)
26
24
Danger of
22
Cavitation
20
Normal Working Condition
18
16
INLET PRESSURE (bar)
14
12
10
Not Applicable
8
0
0 2 4 6 8 10 12 14 16 18 20
OUTLET PRESSURE (bar)
13
ACV
AUTOMATIC CONTROL VALVES
CONTROL VALVES APPLICATIONS
A) NETWORK CONTROL VALVES
1- PRESSURE REDUCING VALVE
• Sustaining
• Flow limiting
• Check
• Solenoid
• Low flow by pass
2- PRESSURE SUSTAINING VALVE
• Flow limiting
• Check
• Solenoid
3- PRESSURE DIFFERENTIAL
4- FLOW LIMITING VALVE
• Check
• Solenoid
15
A) NETWORK CONTROL VALVES
(FLOW AND PRESSURE CONTROL)
16
B) LEVEL CONTROL VALVES
3- ALTITUDE VALVE
(SIERRA MODEL 1600)
Maintains a constant level of water in elevated tanks.
It is different from float valves in that it senses
changes in pressure through a sensing line
connected to the tanks drainage pipe.
17
C) NETWORK PROTECTION VALVES
1- PRESSURE RELIEF VALVE
(SIERRA MODEL 1200R)
Protects the pipeline from damages that can be
caused by high pressure peaks by relieving excess
pressure out of the system.
2- SURGE ANTICIPATING
(1200R-11)
Limits water hammer effects due to sudden pump
shutdown or power failure.
18
D) ELECTRIC VALVES
3- MOTORIZED PILOT
(SIERRA MODEL 2300)
The model 2300 is a series of motorized pilots that
can be used with all network control valves; pressure
reducing, sustaining and flow limiting valves. The
motorized pilot is basically a conventional hydraulic
pilot that is driven by a motor for remote set point
adjustment.
A typical application of PRV electric control pilot is the
pressure management application.
19
Sierra Automatic Control Valves
are hydraulically operated pilot
actuated globe valves that are
used to control pressure, flow
or level in water and irrigation
networks.