1. General notes for users of the Service Manual VAP 20/30/40

This manual was written exclusive for the service staff of C. Gerhardt GmbH & Co. KG and for the
service staffs of our international agencies.

This service manual shall help to get a deeper knowledge of how the instruments are constructed and
how they work. It is an important tool to service and repair the instruments in a safe, competent and
specific way. The transparent structure and the appendix of modification information will enable to
order and to store the most useful spare parts. This manual will make servicing easier, in particular for
our international agencies.

To provide yourself against risks during operation or service, the following safety instructions should be
obeyed:

Make sure that no liquid gets into contact with cable connections or the interior of the electrical
parts of the unit! Danger of electrical shock!

Repairs on electrical, electronic or mechanical parts must only be done by authorzied

personnel.

Always switch off the apparatus at the mains and pull the plug before opening! Danger of
electrical shock!

The apparatus must be used according to the instruction manual. It is not allowed to make
changes to the apparatus in order to modify its application.
 2 0 0 2 9 0 3 0 0 2 4 1 2 4 0 2 8 0 3 8 0 2 6 1 2 6 0 5 8 0 1 1 0 0 5 0 3 1 1 1 0 4 4 0

2 5 0
2 5 1

2 1 0
2 7 0

5 1

3 3 0

3 4 0

3 2 0 3 1 0 2 0 1 0 2 2 0 1 1 2 0 2 3 0 2 0 8 0 4 5 0
9 9 5

3 5 0

F r o n t V ie w
V A P 2 0 /3 0 /4 0
Date: Key to Front view VAP 20/30/40
Drawing-No. Part-No. Description Modif. 1 Modif. 2 Modif. 3 Modif. 4

10 50014 Case, C.G. yellow

20 50015 Drip tray PP, VAP 20 - 40
50 50018 Holder VK/DK VAP 20 - 40
51 50020 Clamp fitting for 50018
80 50003 Quick clamping device for sample tube, compl.
50012 Wedge, PP
13308 Switch for clamping device
200 7472 Distribution head, glass
210 6470 Viton cone
220 7673 Distillation condenser
230 6474 Ventilation valve, PP, for distillation condenser
240 16604 Screw cap GL 32, open
241 16607 Silicone seal GL 32
250 16602 Screw cap GL 18
251 16606 Silicone seal GL 18
260 16601 Screw cap GL 14
261 16609 Silicone seal GL 14, with tubing connection
270 30698 PTFE - sieve for steam inlet tube
280 11810 PTFE - inlet tubing, steam
290 11811 PTFE - inlet tubing, NaOH
300 50021 Distance piece for distribution head
310 40234 Tubing holder for H3BO3
311 25102 Dummy plug for 8mm hole
320 19015 Plexiglass protection door, bottom 02.05.96
330 19016 Plexiglass protection door, top 02.05.96
340 18250 Door hinges 02.05.96
350 18251 Door handle
380 17542 PP-tube joint
440 17940 Rubber foot, 5mm
450 17945 Rubber foot GF 21, self-adhesive
580 18404 Cable binder
1100 22705 Silicone tubing 8/16
1120 20903 Silicone tubing 6/10 16.03.95
2010 22704 Silicone tubing 8/12

Page 1
 1 6 3 1 6 21 1 7 01 6 0 1 6 2 1 1 6 0 4 0 0 3 9 0 3 6 0 4 1 0 1 1 1 0 4 9 0 1 0 3 7 0
S 3
3 8 5

9 0 4 5 6
4 5 5
1 1 1 0
S 2
S 3

S 2
1 1 7 0
4 3 0
7 0
1 1 5 0
5

S 1
8

S 1

to c o n d e n s e r

3 0 9 9 0 4 8 0 8 1 8 0 2 9 0 9 9 0 4 0 9 9 8 5 2 0

R e a r V ie w
4 8 6 6 0
V A P 2 0 /3 0 /4 0
Date: Key to Rear View VAP 20/30/40
Drawing-No. Part-No. Description Modif. 1 Modif. 2 Modif. 3 Modif. 4

10 50014 Case, C.G. yellow

30 50016 Pump-holding module VAP 20 - 40 (see 4.1)
40 50017 Tubing-connection module VAP 20 - 40 (see 4.2)
60 50019 Rear cover VAP 20 - 40, C.G. yellow
70 40850 Steam Generator DE 94 (see 4.5) 11.08.95 27.09.95
80 50003 Quick clamping device for sample tube, compl.
81 13308 Switch (Tube present)
90 40890 PCB-module 230 V, VAP 20, compl. (see 4.3)
40891 PCB-module 230 V, VAP 30, compl. (see 4.3)
40892 PCB-module 230 V, VAP 40, compl. (see 4.4)
160 10385 Pinch-solenoid valve S 307 20.06.95
161 10389 Tube holding device for valve 10385
162 11003 Plug with bridge rectifier for valve 10385
163 40269 Ventilation vessel, glass 20.06.95
290 11811 PTFE inlet tube, NaOH
360 50024 PP - connector
370 40249 Screw connection, (part 3) for 50024
385 40239 PP - dummy plug for 50024
400 10318 PP - connection, bent, DN 08 R 1/8"
410 10317 PP - connection, bent, DN R 1/8"
430 50023 Tubing connection, PP, 51x10x5
455 27309 Silicone - red 15x80x5 (base for Steam Generator)
456 27310 Silicone - red 15x15x3 (base for Steam Generator)
480 18411 Guiding spout
486 25121 Cap Heyco, d = 22,5mm
490 17914 Band clamp fitting OBO - Quick PG 21
520 17920 Clamp 12H8074
600 23230 Set screw VA M4x30 DIN 551
610 23002 Label for ground connection, M4, 9x18, Al
1110 20914 Silicone-tubing 4x7, from pump H2O to 50024
1150 20920 Verprene-tubing 4x8 30.03.95
1160 20921 Verprene-tubing 8x12
1170 20919 Neoprene-tubing 4,8x1,6 approx. 170mm and 520mm
 9 8 0 8 0 0

to s te a m g e n e ra to r
5 to 5 0 0 2 4
(re a r)
E 1

2
4

to
g r o u n d c o n n e c t io n to
1 0 0 R e c e iv e r

6 9 0 5

6 6 0 1 0 0
2

1 0 0
E 1

E 2
to 5 0 0 2 4
to 8 0 0
D is t r ib u tio n H e a d
9 8 1
4 6

t o c o n n e c t io n p ie c e
2 9 0
5 1 x 1 0 x 5
E 2
to
S a m p le T u b e C la m p in g D e v ic e

5 7 0
6
9 9 2
6 8 0 1 1 0 9 9 2 3 0 9 9 0 4 8 0
1 0 0
4 1 0 7 0 0 4 0 0

P u m p H o ld in g M o d u le
V A P 2 0 /3 0 /4 0
Date: Key to pump-holding module VAP 20/30/40
Drawing-No. Part-No. Description Modif. 1 Modif. 2 Modif. 3 Modif. 4

30 50016 Pump-holding module VAP 20 - 40

100 10310 Diaphragm-pump PML 1140-ND100 (see 6.0) 30.03.95 15.12.95
110 10360 Peristaltic-pump SR25 230 V
290 11811 PTFE - inlet tubing NaOH
400 10318 PP - connection, bent, DN 08 R 1/8"
410 10317 PP - connection, bent, DN 06 R 1/8"
480 18411 Guiding spout
570 22701 Clamp VZ N10
660 18421 SES Markers S-9-J/2
680 18423 SES Markers S-9-J/4
690 17424 SES Markers S-9-J/5
700 18425 SES Markers S-9-J/6
800 11140 Multiple contact strip
980 20050 Insulation tube sw 6x0,5
981 20072 Insulation tube sw 5x0,5
 8 0 0
8
to s a m p le tu b e
c la m p . d e v ic e

to P o w e r P C B

8 1 5 0
to c o n d e n s e r

4 2 0 to p e r is ta lt ic -
p u m p (p re s s u re )

4 8 5

4 3 0

to c o n d e n s e r
1 1 0 0 9 9 0 4 0 5 1 0 5 0 0 1 1 5 0

T u b in g C o n n e c tio n M o d u le
V A P 2 0 /3 0 /4 0
Date: Key to tubing connection module VAP 20/30/40
Drawing-No. Part-No. Description Remark Modif. 1 Modif. 2 Modif. 3

40 50017 Tubing-connection module VAP 20 - 40

150 17109 Magnetic valve with pressure control 0,5 bar, 5 l
420 50022 Connection piece, PP, 51x10x10
430 50023 Connection piece, PP, 51x10x5 (only VAP 30/40)
485 25120 Cap, Heyco, d = 15,1mm (only VAP 20)
500 17908 Band clamp fitting
510 17907 Band clamp fitting (only VAP 30/40)
800 11140 Multiple contact strip
990 17960 VA - screw 1411 KA 50x25
1100 22705 Silicone tubing 8x16
1150 20920 Verprene tubing 4x8 (only VAP 30/40)
 a 1 1 1 0 2 0

to p re s s u re s e n s o r
( c o o lin g w a te r ) 4 0
1
2
to m ic r o s w itc h

3
4
5
6
( tu b . c la m p . d e v ic e )

7
8
f1 to S te a m -
g 1
g e n e ra to r (fro n t)
f2
g 2

rd t
rh a
G e
5 1 b 1

d
b 2
d b 3
b 4
c 1 h 1
e 1
a

3 0
e 2

s t
d e
b 3

p o
f2

V a
2

5 0
3
1

f1

h 1

h 2
b 4

c 2
8 0 to
re a r c o v e r
c 1 to
g r o u n d c o n n e c tio n
c 2
h 2

7 0 , 7 1 b 1

b 2
e 1

e 2
P C B - m o d u le
6 0 7 2
g 2

g 1
9 0
V A P 2 0 /3 0
Date: Key to PCB-module VAP 20/30/40
Drawing-No. Part-No. Description Modif. 1 Modif. 2 Modif. 3 Modif. 4

10 11222 Control - PCB VAP 20/30

11225 Control - PCB VAP 40
11 11223 Power - PCB 230 V, VAP 20/30/40
12 11227 Display VAP 40
20 11213 Keyboard VAP 20
11214 Keyboard VAP 30
11215 Keyboard VAP 40
40 11750 Switch, green illuminated
50 15350 Semiconductor relay WG-A5-6D25
51 15351 Cap for 15350
60 14401 Plug connection 161.5, for mains cable
70 21417 Fuse holder, 16 A
71 21420 Bayonet type cap for fuse 5x20 (for 21417)
72 12703 Socket with byonet catch, 3 pin
80 18690 Plug housing 021 032 660
new 17916 Clamp fitting (for tube at pressure sensor)
 2 0
4 0

a 1 1 1 0 1 2

to p re s s u re s e n s o r

rd t
rh a
( c o o lin g w a t e r )

G e
1
2

to m ic r o s w itc h
3
4
5

b 1
( t u b e c la m p . d e v ic e )
6
7
8

d
f1 to S te a m - b 2
g 1 b 3
g e n e ra to r (fro n t) b 4
f2 h 1
g 2
a

4 0
s t
d e
p o
V a
5 1
d

c 1
e 1

e 2
b 3
f2
2

5 0
3
1

f1

h 1

h 2
b 4

c 2
8 0 to
re a r c o v e r
c 1 to
g r o u n d c o n n e c t io n

c 2
h 2

7 0 , 7 1 b 1

P C B - m o d u le
e 1

e 2
b 2

g 2

6 0 7 2
g 1
9 0
V A P 4 0
 3 2 0 2 1 0 2 0 0 3 3 0 1 4 0

3 1 0
5 0 2

5 3 5
5 1 5
3 0 0
E 2 5 0 0

5 0 5

3 5 0
E 1
5 0 0
5 3 0
8 9 0

E 2

3 4 0 4 0 0
E 1

S te a m G e n e ra to r
V A P 2 0 /3 0 /3 0
 3 2 0
n e w s e n s o r , P a r t- N o . 4 0 8 5 7 s in c e ( 1 2 /9 5 )

3 3 0

5 1 5
3 0 0
E 2 5 0 0

5 0 5

3 5 0
E 1
5 0 0
5 3 0
8 9 0

E 2

M o d ific a tio n 1 1 .0 8 .1 9 9 5 , P a g e 2 3 4 0 4 0 0
E 1

T o g e th e r w ith th e c h a n g e m e n t o f th e le v e l s e n s o r , a ls o th e s te a m g e n e r a to r h a s b e e n c h a n g e d .
U n d e r th e s a m e P a r t- N o . 4 0 8 5 0 n o w o n ly th e n e w s te a m g e n e r a to r w ill b e d e lie v e r e d .
Date: Key to steam generator VAP 20/30/40
Drawing-No. Part-No. Description Modif. 1 Modif. 2 Modif. 3 Modif. 4

140 40863 Level sensor 11.08.95

300 21115 Multitherm 550 HD, 400x500x3mm
320 20604 Excess-pressure valve, 604T
330 20620 SKT - Ventilation valve
340 12354 Tubular heating element, 230 V
350 12307 Excess-temperature device
400 18787 Plug-in connection piece + label for ground connection
890 18691 Plug 020 030 660
 A rt.-N r. 1 0 3 2 9

F Y D L /N M 2 M 1 B Z

D ia p h r a g m P u m p
E C K 1 0 3 1 0
 Spare parts for diaphragm pump 10310

1) Pump-head comprising of the following parts:

Part-No. Drawing-No. Description Quantity

10330 F Cover of pump head 1
10325 D Connection-piece for square connections 1
10322 B Distance piece 1
10323 C,E O-Ring 2
10326 K O-Ring 1
10320 Y Diaphragm 1
10327 M1 Valve plate (PTFE) 2
10328 M2 Valve plate (stainless steel) 2
10324 L,N Clamp for valve tiles 2
17911 - Angle-connection (inlet ) 1
17910 - Angle-connection (outlet ) 1
10321 Z Diaphragm with lip and screw 1

Attention !
In instruments Vap 20/30/40 there are different angle-connections for the pump
NaOH.
Angle-connections Part-No. 17911 and 17910 are replaced against the following
connections.

10317 - PP - angle-connection ( NaOH - outlet ) 1

10318 - PP - angle-connection ( NaOH - inlet ) 1
20918 - Isoversinic-tubing 1
see modification 2 from 30.03.1995

For pumps H2O Part-No. 17911 and 17910 are valid.

2) Other spare parts are not available. In case of damage customers only can
order
the complete pump 10310 .
Date: Spare parts and accessories VAP 20/30/40
Part-No. Description Modif. 1 Modif. 2 Modif. 3

18560 PC - Label 67x72: Caution ! Before opening rear wall...

18561 PC - Label 32x50: Pump Suction (VAP 30/40)
18562 PC - Label 32x50: Pump H2O-sample (VAP 30/40)
18564 PC - Label 18x36: Cooling water outlet
18565 PC - Label 22x41: Pump NaOH
18566 PC - Label 18x79: Excess-temperature device
18567 PC - Label 18x78: Excess-pressure outlet
18568 PC - Label 32x50: Cooling water inlet with sieve
18569 PC - Label 32x50: Pump H2O-steam generator
26926 PC - Label 95x59: inside the instrument
26925 PC - Label 130x98: rear of PCB module
22802 Water inlet tubing 10/17, 2m
25450 PVC - pipe 6x1
25451 PVC - pipe 10x1
20921 Verprene-tubing 8/12 (for sample waste VAP 30/40)
22601 PVC - tubing 4/7, 2m (for pumps H2O dist.)
22604 PVC - tubing 8/12, 2m (for tank NaOH and cooling water outlet)
1311 Mains cable, 2m
7629 Set of tanks KAN20, with level switch
7639 Set of tanks KAN30, with level switch
7649 Set of tanks KAN40, with level switch
6471 Viton cone VK micro, for 100ml tubes KMT
4260 RS 232/485 ARS
4261 Data cable DK 42 for RS 485, 2m
4262 Data cable DK 45 for RS 485, 5m
4264 Data cable DK 22 for RS 232, 2m
4265 Terminator AST
Date: Modification kit Devarda for VAP 20/30/40
Part-No. Description Modif. 1 Modif. 2 Modif. 3

7474 PP - distribution head Devarda, VPD 7, bottom (instead of 7472)

7475 Distribution head Devarda, glass, VGD 7, top (instead of 7472)
30244 Ventilation valve for condenser, glass
7676 Condenser, shortened (instead of 7673)
40213 PP - adaptor
50025 PP - distance piece for distribution head (instead of 50021)
16604 Screw cap GL 32, open
16607 Silicone - seal GL 32
Date: Modification kit Bi-dist for VAP 20/30/40
Part-No. Description Modif. 1 Modif. 2 Modif. 3

50027 Holder for customer´s Bi-Dist installation

50026 Rear cover C.G. (instead of 50019)
17103 Magnetic valve without pressure control
17110 Flow control for cooling water, MR 05
40231 Sample outlet, PP transparent
17908 Clamp VZ 12-22/9
17907 Clamp VZ 8/7 (VAP 30/40)
25121 Cap Heyco, d = 22,5mm
25122 Cap, Heyco, d = 34,8mm (VAP 20)
11140 Multiple contact strip
18424 SES - Markers S-9-J/5
18560 PC - Label 67x72: Caution! Before opening rear cover...
18564 PC - Label 18x36: Water outlet
18565 PC - Label 22x41: Pump NaOH
18566 PC - Label 18x79: Excess-temperature device
18567 PC - Label 18x78: Excess-pressure outlet
18568 PC - Label 32x50: Cooling water inlet with sieve
18569 PC - Label 32x50: Pump H2O-steam generator
18561 PC - Label 32x50: Pump suction (VAP 30/40)
18562 PC - Label 32x50: Pump H2O-sample (VAP 30/40)
Date: Other parts and accessories for VAP 20/30/40
Modification to PP- distribution head

Part-No. Description Quantity Modif. 1 Modif. 2 Modif. 3

7482 PP - distribution head VAP 20 (instead of 7472) 1

7676 Distillation condenser VAP 20 (instead of 7673) 1

Modification to Büchi

Part-No. Description Quantity Modif. 1 Modif. 2 Modif. 3

7483 Distribution head, glass (instead of 7472) 1

Modification to micro

Part-No. Description Quantity Modif. 1 Modif. 2 Modif. 3

6471 Viton cone micro 1

Modification to acid-restistant

Part-No. Description Quantity Modif. 1 Modif. 2 Modif. 3

30244 Ventilation valve, glass (instead of non-return valve 10329) 1

20918 Isoversinic-tubing 6x12 (instead of PVC-tubing at pump NaOH) 45mm 30.03.95
27101 Clamp VA 6-16 (to fasten 20918) 30.03.95
10327 Valve plate PTFE for pump NaOH 2 15.12.95
8.0 Steam Generator

8.1 General description of steam generation

After switching-on the Vapodest the electronics measures the level of water inside the steam
generator via the level sensor. In case of a level below minimum, the pump for H2O steam
generator is switched on until the level sensor detects sufficient water inside the steam
generator. This will take some seconds.
Then the semiconductor relay switches on the tubular heating element with maximum power
to reach the necessary steam pressure for the distillation. When this pressure is reached, the
maximum heating power is switched off and the instrument reverts to stand-by with a
regulated and controlled heating. The instrument now is ready for distillation.
When starting a distillation the instrument will heat with a selected power from 30% - 100%
(VAP 20/30) or 40% - 100% (VAP 40). The steam will reach the sample tube via pinch-
solenoid valve(s), ventilation glass, PP-distributor and steam inlet tube. During this procedure
the level inside the steam generator will decrease. This is recognized by the level sensor and
the pump H2O for the filling of the steam generator will be switched on. If there is no sample
tube present or if the tap for cooling water is not open, a distillation is not possible.

Remark:

Especially if the water for the steam generator is not very clean or if there any kind of dirt
within the reservoir, the following problem may occur:
- After some distillations the instrument shows the error message „E3“, no water for steam
generator and the program stops.
- After pressing „RUN“ the display shows „H“, wait for steam.

Explanation:

If the steam generator is contaminated with dirt, the boiling and bubbling water will build up
foam above the water level. The level sensor detects the foam as water and prevents the
pump from running even though the water level in the steam generator is not sufficient. After
some time the liquid level or the foam will have diminished to such an extent that no more
liquid is detected, and the system switches on the pump. Within 15 s a sufficient water level
should now be detected. As this is not possible in such a short time the error „E3“ will appear
on the display.

If the „RUN“ key is now pressed, the system will get into the filling mode and the steam
generator will be filled to the height stipulated. However, at the same time, due to the cold
water, the steam pressure collapses, and the unit heats up again until stand-by is reached.
Only now further distillations can be run. So please note that a reaction as described is not a
malfunction, but a sign of unwanted foam in the steam generator. If this happens, clean the
steam generator and the reservoir.
8.2 Safety devices for steam generation

8.2.1 Level sensor

8.2.2 Excess-temperature device
8.2.3 Pressure sensor
8.2.4 Excess-pressure valve
8.2.5 Micro switch for sample tube

8.2.1 Level sensor

The level sensor constantly controlls and regulates the level of water inside the steam
generator.The sensor itself is constantly checked by the electronics; in case of a malfunction,
the instrument will give an error message. If the level detection system fails totally, the tubular
heating element will be switched off in case of a level decreasing under the allowed minimum
range.
The level sensor can only compare between insufficient or sufficient water inside the steam
generator. This is done by changing the frequency it sends to the Control-PCB.

8.2.2 Excess-temperature device

In case that due to a total failure of the level sensor and the control electronics lack of water
in the steam generator cannot be detected, the tubular heating element must be protected
against overheating. In such a case the excess-temperature device will switch off the heating
circuit at about 150°C. After trouble shooting and cooling off of the steam generator the pin of
the excess-temperature device has to be pressed back into position. Now the next distillation
can be started.

8.2.3 Pressure sensor

The pressure sensor is placed directly on the Control PCB and continuously checks the
pressure inside the steam generator. If this sensor detects a higher pressure than 0,45 bar,
the tubular heating element is switched off, and the instrument gives an error message.

8.2.4 Excess-pressure valve

In case of a total failure of pressure sensor and control electronics, the instrument must be
protected against an increasing pressure. At about 0,5 bar the excess-pressure valve will
open mechanically so that any damage of the instrument can definitely be avoided . If this
happens, the instrument has to be switched off immediately.

8.2.5 Micro switch for sample tube

This switch ensures that a distillation is not run without a sample tube. In case you try to start
the system without a sample tube, the start is prevented by the switch. Thus there is no
danger of scalding.
8.3 Testing the safety devices for steam generation

8.3.1 Level sensor

8.3.2 Excess-temperature device
8.3.3 Pressure sensor
8.2.4 Excess-pressure valve
8.2.5 Micro switch for sample tube

8.3.1 Level sensor

With a filled steam generator a frequency < 20 KHz should be measured.

With an empty steam generator a frequency >130 KHz should be measured.

Measurement of the frequencies VAP 20/30:

To measure the frequency the gauge has to be connected to collection plug P4 at pins 2 + 3.
P4 is to be found on the Power PCB, above those orange coloured plugs.The occupation of
P4 is to be found in the circuit diagram (see 4.2).

P4 KHz

8
7

Measurement of frequency VAP 40:

At instruments of the type Vapodest 40 the frequency can be checked with the inbuilt test-
.
program without opening the rear wall. To enter the test-program the keys „ “ and „ 9 “ have
to be pressed at the same time. The instrument shows the menu display for the I/O Test and
the frequency can be read:

filled steam generator H(igh) about 5 KHz

empty steam generator L(ow) about 90 KHz
.
To quit the test-program the keys „ “ and „ Reset “ have to be pressed at the same time. It is
also possible to measure the frequency as in the description for VAP 20/30. The same values
are valid.
8.3.2 Excess-temperature device

The adjustment of the excess-temperature device should not be changed. It has been
adjusted here at C. Gerhardt so that an excess-temperature of about 150° C will open the
heating circuit. This device is directly switched into the the 230 V circuit. A damaged excess-
temperature device should not be bridged but replaced immediately.

8.3.3 Pressure sensor

The pressure sensor is maintenance-free. In case of problems with pressure measuring or in

case of a broken pressure sensor, the complete Control - PCB has to be changed (see 10.).

The way to measure the pressure inside the steam generator is as follows:

VAP 20/30

When the Vapodest is still cold, a gauge for pressure measurement 0 - 1 bar has to be
connected into the line from steam generator to pressure sensor as the schematics shows.
If available, connect an instrument to measure the current the instrument draws into the
mains circuit.

Switch on the Vapodest. The electronics will measure the level of water inside the steam
generator and, if necessary, the pump for H2O will run. Then the heating element is switched
on.
When the pressure inside the steam generator begins to increase, the ventilation valve will
close, and the pressure of about 0.2 bar will build up. The instruments switches into stand-by
and indicates that it is ready for distillation.
If the instrument goes into stand-by well below or well above than 0.2 bar, the Control-PCB
has to be replaced (see 10.).
When measuring the pressure it is important to make sure that all tubing connections are
fixed properly. The connections should only be loosened when the instrument has cooled
down:
Risk of scalding because of hot steam of more than 100°C!

to steam valve
bar

to pressure sensor

steam generator
H2O steam generator
 VAP 40

At instruments of the type Vapodest 40 the pressure can be checked with the inbuilt test-
.
program without opening the rear wall. To enter the test-program the keys „ “ and „ 9 “ have
to be pressed at the same time. The instrument shows the menu display for the I/O test. The
pressure as measured by the pressure sensor can now be read.
.
To quit the test-program the keys „ “ and „ Reset “ have to be pressed at the same time.

8.3.4 Excess-pressure valve

The adjustment of the excess pressure valve should not be changed. It has been adjusted
here at C. Gerhardt so that an excess-pressure of about 0.5 bar will activate the valve.
The following instructions will help to adjust the excess-pressure valve if it becomes
necessary nevertheless.

When the Vapodest is still cold, a gauge for pressure measurement 0 - 1 bar has to be
connected to the steam generator as the schematics show. The tubing to the pressure
sensor is left without any connection to prevent the switching off of the heating when reaching
a pressure of 0.2 bar.
If available connect an instrument to measure the current the instrument draws into the
mains circuit.

to steam valve

bar

to pressure sensor
X
steam generator
H2O steam generator

Switch on the Vapodest. The electronics measures the level of water inside the steam
generator and, if necessary, the pump for H2O will run. When a sufficient water level is
reached the heating element is switched on.
When the pressure inside the steam generator begins to increase the ventilation valve will
close, and the pressure is able to increase more and more because of the disconnected
pressure sensor. Observe carefully the increasing pressure, and make a note at which
pressure the excess-pressure valve opens. In case that the valve does not open at a
pressure of about 0.5 bar, immediately switch off the instrument!
 Excess-pressure valve has to open earlier (lower pressure):

Remove the brass cap and slightly loosen the big nut. Turn the adjusting screw slightly anti-
clockwise, and tighten the nut very well. Take care that the adjusting screw stays in the
adjusted position. When the adjustment is done, repeat the above described procedure to
test the excess-pressure valve.

Excess-pressure valve has to open later (higher pressure):

Remove the brass cap and slightly loosen the big nut. Turn the adjusting screw slightly
clockwise, and lock the nut very well. Take care that the adjusting screw stays in the adjusted
position. When the adjustment is done, repeat the above described procedure to test the
excess-pressure valve.

When measuring the pressure it is important to make sure that all tubing connections are
fixed properly. Carefully observe the increasing pressure and make sure you do not touch the
hot excess-pressure valve. The connections should only be opened when the instrument has
cooled down:
Risk of scalding because of hot steam of more than 100°C!

8.3.5 Micro switch for sample tube

This switch prevents the start of a distillation without any sample tube. Without a tube the
switch is activated, which means that the circuit is open. With a sample tube the switch is not
activated, and the circuit is closed.The switch is located inside the instrument directly fixed on
the clamping device for the sample tube.

8.4 General description of steam inlet / sample suction

Steam inlet:

During stand-by steam of about 0.2 bar only reach the steam valve. During stand-by both
valves, steam valve and shut-off valve are dead. After starting a distillation, the steam valve
gets alive which means it will open. The ventilation valve however, still stays dead, so that it
is open for steam. The steam now can pass through the steam valve, ventilation glass, shut-
off valve, PP-distributor and steam inlet tubing into the sample tube. From there the distillate
will pass through the distribution head and the condenser into the receiver. The ventilation
valve of the condenser must be closed. The steam can also pass through the PP-distributor
until it reaches the pump for sample suction. Steam will also pass through the tubing for the
dilution of the sample until it reaches the non-return valve of the pump for H2O sample.

a) Way of steam during stand - by

3 2 1

4
5

Steam Generator

6 7
b) Way of steam during distillation

3 2 1

4
5

Steam Generator
6 7

1 = Shut-off valve 4 = PP - connector

2 = Ventilation glass 5 = Inlet tube steam
3 = Steam valve 6 = Tubing H2O sample 7 = Tubing suctioning

Sample suction:

After the distillation the steam valve will not draw current any longer, and it closes the path to
the ventilation glass. For suctioning now the shut-off valve will get alive and it closes the
tubing. too. Consequently the pump for sample suctioning is able to empty the sample tube.
In this case the ventilation valve of the condenser must open. If not, the pump will also empty
the receiver.
The pump for sample suction also draws against the pump for sample dilution.

3 2 1

4
5

Steam Generator
6 7

8 8 = Pump suctioning
9 = Pump H2O sample

9
sample tube
9.1 Diaphragm pump

The diaphragm pumps used in VAPODEST instruments are almost maintenance-free.

Depending on the kind of liquid the volume the pumps deliver is about 100ml / 10 s. Make
sure that the tanks are not placed in a higher position than the instrument itself.
It may occur that the volume becomes less than the normal range because of dirt deposit
inside the pump housing. In this case the pump and the valves inside the pump housing
should be cleaned.

Cleaning the valves:

To clean the pump it is necessary to disconnect all the tubes and to remove the rear wall.
Loosen the 4 screws from the badly working pump, and take away the cover of the pump
head. Also take away the connection-piece for angle connections and the diaphragm.
Carefully loosen the clamp for the valve plates and the valve plates themselves. Clean all the
parts and re-assemble the pump ensuring that all parts are put back into the right position.
Close the rear wall, and do not forget the ground connection! Install again all the tubings and
let the instrument run to see if everthing works well.

L
D

M1 / M2

( see 6. )

L = Clamp for valve tiles

D = Connection piece for square connections
M1 / M2 = valve plates
9.2 Peristaltic pump

Also the peristaltic pumps are maintenance-free. At least once a year the neoprene tubing
should be replaced:

- Remove inlet and outlet tube

- Twist s-shaped bar on the left hand side of the pump
- Take out the plastic housing containing the tubing
- When fitting the new tubing ensure that the u-shaped lugs locate in their recesses to fix the
tube into the plastic housing
- The complete plastic housing is now inserted into the guides of the pump body before
locking in position with the S-bar

S-shaped bar plastic housing

Description Part-No.
Plastic housing for tubing 10327
Spare tubing Neoprene 10370
Guides for the pump body. 10371
S-shaped locking bar 10373
Replacement of the Control PCB

With the new Vapodest 20/30 it is possible to exchange the Control PCB from a Vap 20 to a
VAP 30.
In case of a service it will now be easier to have the right PCB on stock because now it does
not matter any longer if the PCB is for a VAP 20 or for a VAP 30. The software will check
which keyboard is present, and then the processor will adapt the PCB.

In order to ensure that the software will work after the replacement of the Control PCB it is
necessary to press „PROG“ and „RESET“ at the same time and to switch on the instrument
while still pressing the keys.
 Modification 16.03.1995

Draw.-No. 1120
Part.-No. 20903

The tubing with part-no.: 20903 is shortened to a length of 150 mm. When installing the
shortened tubing the angle has to be adjusted to the angle of the condenser outlet.

adjust angle of tubing

Modification beginning with series numbers:

VAP 20 from VAP 000233

VAP 30 from VAP 000182

 Modification 1 from 30.03.1995

Draw.-No.: 1150
Part-No.: 20920 only VAP 30/40

The silicone-tubing part-no. 20914 from pump H2O to PP-distributor is replaced against
Verprene-tubing Part-No. 20920.

Additionally there is clamp Part-No. 17907 used. It fixes the new tubing to the PP-distributor.

Modification beginning with series numbers:

VAP 20 from VAP 000242

VAP 30 from VAP 000183

 Modification 2 from 30.03.1995

Only diaphragm pump NaOH, Part-No. 10310!

The PVC-tubing between PP-angle connection (10317) and the PVC non-return valve (10329)
is replaced against Isoversinic-tubing part-no. 20918.
The other diaphragm pumps are not modified.

Additionally there are 2 clamps Part-No. 27101 used to fix the new tubing on both ends.

Modification beginning with series numbers:

VAP 20 from VAP 000242

VAP 30 from VAP 000183

 Modification 20.06.1995

Draw.-No.: 160, 163

Part-No.: 10385, 40269

Due to modifications of the solenoid pinch valves the following kit is to be used for
replacement:

Modification-kit part.-no.: 2/760050

2. After modification ventilation glass part-no. 40269 is replaced by ventilation glass part-no
40272.(Part of modification kit)

Modification beginning with series numbers:

VAP 20 230 V VAP 000294

240 V VAP 000180

VAP 30 230 V VAP 000379

240 V VAP 000173

VAP 40 230 V VAP 000349

 Modification 11.08.1995

As the technology of the new level-sensors has changed, they now have 4 contacts
instead of 3. If you have to install one of the new sensors/boilers into older
instruments, you will have problems with the connections at VAP 20/30. In order to
do so you have to modify the cabling between the power PCB and sensor plug.
Depending on the cabling of the sensor there are two possible ways of modification:

Older version: cabling white, brown, green

green
brown
1 white
P1, sensor PCB
P4, VAP 20-40
power PCB
ground, boiler

Newer version: cabling blue, brown, black

black
brown
1 blue
P1, sensor PCB
P4, VAP 20-40
power PCB
ground, boiler

Modification beginning with series numbers:

VAP 20 230 V VAP 000279
240 V VAP 000180
VAP 30 230 V VAP 000361
240 V VAP 000173
VAP 40 230 V VAP 000346
 Modification 27.09.1995

As adaptor for the outlet of the steam generator a connection piece part-no. 17915
and a silicone-tubing(6x10 mm, lenght 45 mm) part-no. 20903 are used to connect
the Neoprene-tubing 20919.
Of the original Neoprene-tubing you have to cut off 45 mm.

Old version New version

Neoprene
20919

Connector
Neoprene-tubing 17915

Silicone
20903

Steam generator Steam generator

Modification beginning with series numbers:

VAP 20 230 V VAP 000294

240 V VAP 000180

VAP 30 230 V VAP 000379

240 V VAP 000173

VAP 40 230 V VAP 000349

 Modification 15.12.1995

Diaphragm pump 10310 NaOH

Only acid-resistant version !

The valve plates made of stainless steel (10328) are replaced by valve plates made
of PTFE No. 10327.(see 6.)

Already modified pumps get the part-no. 10311