Knauer WellChrom HPLC-Pump K-120 User manual

●Wissenschaftliche Gerätebau Dr. Ing. Herbert Knauer GmbH ●Hegauer Weg 38 ●D-14163 Berlin GERMANY
●Telefon: [phone] ●Fax: [phone] ●Email: [email protected] ●www.knauer.net
WellChrom
HPLC-Pump K-120
HPLC-Pumpe K-120
Manual / Handbuch
V7517, 03/2007

CONTENTS
SOP´s in this manual 4
General description 5
Setup of the HPLC pump K-120 6
Delivery Content 6
Front view of the HPLC pump K-120 6
Pump head identification 7
Connection of the pump head 7
Rear view of the HPLC pump K-120 8
Rear panel 8
Bottom elements 8
Operating the HPLC pump K-120 9
Power supply 9
Adjusting the flow rate 9
Connection of the pump head 11
Automatic switch-off of the pump 11
External control 13
Remote control 13
Assembling a remote control cable 13
RS-232 interface 14
Maintenance by the user 16
Piston backflushing 16
Removing the pump head 16
Removing and checking piston rods 17
Disassembling the pump head 17
Check valves 20
Spare parts and accessories 22
Technical Data 23
Warranty statement 44
Declaration of conformity 45

INHALT
SOP´s in diesem Handbuch 24
Allgemeine Beschreibung 25
Inbetriebnahme der HPLC-Pumpe K-120 26
Lieferumfang 26
Vorderseite der HPLC-Pumpe K-120 26
Frontansicht 26
Pumpenkopf-Identifikation 27
Pumpenkopf- und Flüssigkeitsanschlüsse 27
Rückseitenansicht der HPLC-Pumpe K-120 28
Bedienelemente Rückseite 28
Elemente an der Geräteunterseite 28
Bedienung der HPLC-Pumpe K-120 29
Netzanschluss 29
Einstellung der Flussrate 29
Anschluss des Pumpenkopfes 31
Sicherheitsabschaltung der Pumpe 31
Externe Ansteuerung 33
Fernsteuerung 33
Konfektionierung der Fernsteuerkabel 33
RS-232 Schnittstelle 34
Wartung durch den Anwender 36
Kolbenhinterspülung 36
Pumpenkopf Wechsel 36
Kolbenstangen ausbauen und prüfen 37
Pumpenkopf zerlegen 37
Kugelventile 40
Ersatzteile und Zubehör 42
Technische Daten 43
Gewährleistungsbedingungen 44
Konformitätserklärung 45

4 SOP´s in this manual
SOP´s in this manual
The Standard Operating Procedures (SOP) provided with this
manual offer a convenient way of structuring complex tasks in the
operation of your WellChrom K-2600 UV detector. They include
step-by-step instructions leading the user through all routine tasks
during operation. They can be used for documentation purposes
and be copied, applied signed, and filed in order to document the
performance of the instrument.
Please operate the instrument and all accessories according
to instructions and SOP´s in this manual. This ensures proper
results and longevity of your equipment.
Table 1 SOP´s in this manual
SOP 1 Internal settings for different pump heads 10
SOP 2 Checking the internal pump head setting 10
SOP 3 Connection of eluent tubings 11
SOP 4 Connecting plug strips 13
SOP 5 Piston backflushing 16
SOP 6 Removing the pump head 16
SOP 7 Removing and checking piston rods 17
SOP 8 Disassembling the pump head 17
SOP 9 Assembling the pump head 19
SOP 10 Installing the pump head 20
SOP 11 Replacing check valves 20
SOP 12 Cleaning check valves 20

General description 5
General description
The HPLC pump K–120 is aspecially designed as a simple low
price HPLC pump. It features a double-piston construction to
deliver solvent flows in a wide range with high consistancy and low
pulsation.
The HPLC pump K-120 is delivered with the new inert pump heads
with ceramic inlays. Two different pump heads are available:
• Analytical pump head (0.001 – 9.999 ml/min),
• Preparative pump head (0.01 – 50 ml/min).
These heads combine the features of the older stainless steel
versions with those of the PEEK ones and replace both from now.
The new features are
• Inert, biocompatible.
• The 10 ml pump head is pressure stable up to 400 bar.
• The 50 ml pump head is still pressure stable up to 150 bar.
• The sealings are easily accessible due to the new splitted
design.
Four different older pump heads can also be used with the HPLC
pump K–1001. These are the analogous stainless steel and PEEK
versions respectively:
• Analytical pump head (0.001 – 9.999 ml/min), stainless steel
• Analytical pump head (0.001 – 9.999 ml/min), PEEK
• Preparative pump head (0.01 – 50 ml/min), stainless steel
• Preparative pump head (0.01 – 50 ml/min), PEEK
Pump heads can be interchanged by loosening only four screws.
Experienced users can disassemble the heads for simple
maintenance tasks like cleaning, changing piston seals etc.
The easy-to-learn use and control of the HPLC pump K–120
proceeds via keys which are clear by the first glance. The pump is
especially useful for routine and batch analyses as well as for
education purposes.

6 Setup of the HPLC pump K-120
Setup of the HPLC pump K-120
Unpack the instrument and check pump and accessories for any
damage due to shipping. Place any claims referring to damage to
the transportation company responsible for shipping.
Please check that the HPLC pump K–120 is complete, using the
section Packing list. Please contact our service department, if
something is missing, in spite of our thorough control procedures.
Delivery Content
1 Pump, including pump head 10 or 50ml, and
accessories
1 Power supply unit 24V/50W
1 Power supply cable
1 Set Tools
1 RS-232 cable
1 Plug strip with connectors
1,5 m Flat cable
1 Set Piston backflushing
1 PTFE eluent filter
1 Set Inlet screw with fittings
1 Operation Manual
1 Guarantee Statement KNAUER
Please fill in the registration card for guarantee and return it
immediately. Please remove the transparent, protective foil from
pump outlet and display.
Front view of the HPLC pump K-120
3
1
2.1
2.2
2.3
Fig. 1 shows the front view of the HPLC pump K -120
Various connections, three keys, and a LED display are located on
the front panel. The flow rate display 1indicates two digits. The
range <1ml is shown with both digits behind the decimal point
(e.g.: .05), the range ≥1ml and ≤10ml is shown like 5.5 and the
range ≥10ml in integer numbers.
The assembling of the pump head is described in the chapter
“Connection of the pump head” on page 7.
1Flow rate display
2Keys
2.1 Flow rate up
2.2 Flow rate down
2.3 START/STOP
3Pump head

Setup of the HPLC pump K-120 7
Pump head identification
The pump heads are labeled on the front side indicating the
ceramics inlay version and the maximum flow rate.
The labels of older stainless steel and PEEK versions respectively
show the maximum flow rate only.
These older pump heads can easily be identified by their color:
black: ⇐biocompatible PEEK-version
metallic: ⇐stainless steel version
Connection of the pump head
All connections for liquids are placed at the front panel of the HPLC
pump K-120, Fig. 1 and Fig. 2.
3.1 Capillary connection
3.2 Capillary of backflush
3.3 Pump head screws
3.4 Label, max. flow rate
3.6 Bushing, inlet
3.7 Bushing, outlet
Fig. 2 Pump head

8 Setup of the HPLC pump K-120
Rear view of the HPLC pump K-120
Rear panel
1
2
3
4
5
6
Fig. 3 Rear view of the HPLC pump K-120
1 Fan
2RS-232 serial interface
3Remote control connection
4Serial number
5Power supply
6Ground connection
The power supply 5and an additional ground connection 6are
there located as well as a RS-232 serial interface 2for external
computer control and remote control input and output 3:
START IN: connection for START/STOP as short circuit (or TTL-low)
against ground
ERROR OUT: output for error signals (open collector) against ground
GROUND: ground connection for start and error signals
Bottom elements
1
2
3
Fig. 4 Bottom elements
1DIP-switch 1 for START IN remote control logic’s
2DIP-switch 2 for START/STOP logic’s
3trim potentiometer screw for safety switch off

Operating the HPLC pump K-120 9
Operating the HPLC pump K-120
Power supply
The WellChrom HPLC pump K-120 operates with a 24V direct
current motor. The power supply unit, part of the delivery, is
equipped with an universal transformer suited for a voltage of 100
up to 240 volt alternating current.
Firstly, connect the power cable to the power supply. Insert the low
voltage cable from the power supply unit into the socket at the rear
panel, item 5in Fig. 3.
The ground connector 6 is located at the lower center of the
rear panel and must be connected to a ground contact.
Otherwise, the instrument (platine) may be damaged.
DIP switch no. 2 , item 2, Fig. 4 on page 8 determines the behavior
of the pump after power-on. If the switch is set to ON, the pump
only starts working after pressing the START/STOP key. If the
switch is set to OFF, the pump starts pumping immediately after
switching on the power supply. Thus, the pump flow can e.g.
simply be controlled by a timer. Independent on the switch position
The version of the internal software is indicated for about 5
seconds on the flow rate display, e.g. 3.1.
Never operate the HPLC pump K-120 without liquid in the
pump head and the piston backflushing! Otherwise the pump
head may be damaged. To proceed the piston backflushing
follow the SOP on page 16.
Adjusting the flow rate
It is possible to adjust the flow rate either externally using the RS-
232 interface, see chapter “RS-232 interface”on page 14 or
manually using the ∆∇keys 2.1 and 2.2 (Fig. 1 on page 6). If the
flow rate is manually adjusted, the resolution and in any case the
display is dependent on the selected flow rate value :
flow rate
ml
example
ml
display resolution
ml
<1 0,15 .15 0,01
>0,99 and <10 2,5 2.5 0,1
>9,9 35 35. 1
By pressing the ∆or ∇key, respectively, the value of the flow rate
increases or decreases by 1 in the last shown digit. Pressing the
key longer than 5 seconds, the change proceeds permanently as
long as the key is pressed. To accelerate the adjustment, the steps
are enlarged by a factor of 10 as soon as the last digit changes
increasing from 9 to 0 or decreasing from 1 to 0.
The upper limits of the flow rate values are depending on the
internal setting for a 10ml or a 50ml pump head. Higher values can
not be entered.

10 Operating the HPLC pump K-120
SOP 1 Internal settings for different pump heads
1. Powering up the pump, the firmware version number will be
indicated for a few seconds.
2. When the version number is presented, press the ∆arrow
key, the ∇arrow key and then the ∆arrow key again
3. On the display the actual setting 10. or 50. is blinking.
4. Pushing now the START/STOP key you can change the
setting. The additional setting 2.5 is not in use. If you choose
this setting, the pump can not operate.
5. Push the ∆key, when the requested setting is selected. The
display shows now 00., while the “.” is blinking.
6. Switch the pump off.
7. Adjust the trim potentiometer screw according to the new
pump head, see Fig. 4 on page 8.
8. Start your pump again by switching it on. It will be in the new
setting mode.
SOP 2 Checking the internal pump head setting
1. Switch on the power supply without starting the pump.
2. Press the ∆key until the display stops changing. You can
read now either 10. or 50.
3. Readjust to the requested flow rate.
The actually delivered flow rate is dependent on the back pressure
of the system. Fig. 5 shows an example for the dependence of the
delivered flow rate on the back pressure . The absolute deviation is
dependent upon the compressibility of the solvent and on the pump
performance.
Flow dependent on back pressure
0
2
4
6
8
10
0 50 100 150 200 250 300
Pressure [bar]
Flow [ml/min]
0,5 ml/min
0,7 ml/min
1 ml/min
2 ml/min
5 ml/min
8 ml/min
10 ml/min
Fig. 5 Deviation of the actual flow rate from the preset value in
dependence on the back pressure (Example)

Operating the HPLC pump K-120 11
Connection of the pump head
Check the equivalence of the pump head size and the internal
setting. Make sure that all connections in your system are
suited for the requested backpressure.
The bushing inlet (item 3.6 in Fig. 2 on page 7) is to connect with
the solvent reservoir. For this purpose follow the SOP 3 having a
look on Fig. 6.
ferrule
fitting screw
teflon tube
Fig. 6 Pump head: Connection of eluent tubings
SOP 3 Connection of eluent tubings
1. Insert the teflon tube into the fitting screw and the ferrule.
Make sure, that the ferrule is in the correct orientation - the
flat side to the tube end, to the pump head.
2. Push the tube end as far as it will go into the pump head
inlet.
3. Tighten the ferrule with the fitting screw by hand.
Automatic switch-off of the pump
The HPLC pump K-120 has no pressure transducer. It is therefore
not possible to control the produced back pressure and to switch
off the pump if the pressure falls below or exceeds a given limit.
Indirectly, the pressure can be controlled by regulating the power
consumption of the pump. The power consumption is approxima-
tely proportional to the back pressure. Thus, by limiting the power
consumption also the maximum pressure reached by the pump
can be limited.
The limitation is regulated by a trim potentiometer screw, item 3in
Fig. 4 on page 8, on the bottom of the pump housing. The
accompanying scale is marked with two points 10ml and 50ml.
These settings apply for the actual pump heads with ceramic inlays
as well as for the older stainless steel versions and they regulate
the power consumption of the motor in such a manner that a
maximum pressure of approximately 400 bar (10ml pump head) or
150 bar (50ml pump head) is not exceeded.
If pump heads are damaged by exerting pressures too high
(>400 bar with 10ml stainless steel, >150 bar with 50ml
stainless steel and 10ml and 50ml PEEK) no guarantee claims
will be taken over by the manufacturer.

12 Operating the HPLC pump K-120
The maximum pressure possible at a given power consumption
decreases with increasing flow rates. Fig. 7 gives an example for
the dependence of the pressure reached with a 10ml pump head
on the flow rate for two different settings of the potentiometer. The
upper curve is achieved with setting the screw to 10ml, the lower
curve with turning the screw only half of the scale.
Power Switch-Off 10 ml pump head
0
100
200
300
400
500
024681012
Flow [ml/min]
Pressure [bar]
position 10 ml
position ~2.5
potentiometer
Fig. 7 Maximum back pressure dependent on flow rate with limited power
consumption (example)
The exact behavior of the curve varies for each pump head. can
serve therefore only as an example and not as a standard!
When using the older PEEK pump heads, please keep in mind that
they may only be operated up to a maximum pressure of ca.
150 bar.
The maximum positions of the trim screw are dependent on
the used pump head. They are 10 ml and 50 ml respectively
for the ceramic and stainless steel versions and 3 for both
PEEK pump heads.
In any case, the pressure should be monitored externally, e.g. by
using a manometer, if the risk of high pressures that can damage
your system occurs.
If an external pressure monitoring is installed, it should be
used for a remote safety switch off, directly pressure
depending. Compare chapter “Remote control” on page 13.

External control 13
2 1
External control
Remote control
The pump can be controlled by external contacts and also con
send signals to other instruments. A special control cable is
necessary for both purposes, see “Assembling a remote control
cable” on page 13.
START IN The pump is stopped by a short circuit or TTL-low at this
contact. If a stop signal is received, the pump will halt. This
external control has priority over both the serial commands
and those ones, entered via key input. The pump can not
be restarted until the signal has been removed. Should you
try to restart it using the START key, the display will blink
once to indicate that this function is currently blocked by an
external signal. The pump will restart once the signal has
been removed (open or TTL-high).
DIP switch no. 1, item 1, Fig. 4 on page 8, determines the
logic of the Start-In input. In position ON (switch to the
outer side of the pump) the pump only works if there is no
short circuit signal at the Start-In input. A short circuit on
these contacts will stop the pump. This situation
corresponds to that on the K-100 pump. Switching the DIP
switch to the OFF-position (towards the middle of the
instrument) inverses the logic of the Start-In input. The
pump works only as long as a short circuit is applied.
ERROR OUT:A signal (open collector) will be given at this contact if the
pump is either halted by an error or if the required rotation
speed is no longer achieved due to the back pressure
being too high. After the pump has halted, the display
starts blinking. Return to the normal display mode by
pressing any key.
Assembling a remote control cable
A different type of control cable must be made for each application.
Use the set plug strips with connectors enclosed in the delivery to
prepare your cable according the following SOP.
SOP 4 Connecting plug strips
1. Insert the rounded end of the lever latch into
the square opening of the selected
connector of the plug strip.
2. Press the latch down as indicated by arrow.
3. Insert the uninsulated end of the cable into
the opening under the latch.
4. Release the latch (1) and remove the lever
latch from the plug (2).
The cable is now firmly anchored in the plug
strip.
Fig. 8 Connecting Plug Strips

14 External control
RS-232 interface
The serial interface at the rear of the instrument, item 2in Fig. 3 on
page 8, allows direct pump control from a computer. If you are
going to integrate your pump in a HPLC system controlled by a
software package like EuroChrom® follow the instructions of the
software manual.
Also simple ASCII codes are able to control the pump. ESC
sequences are not needed. Thus, a simple terminal program may
be used. The specifications for data transfer are:
9600 baud
8 bit
1 stop-bit
no parity check
The following functions can be controlled by the PC. After
successful command transfer, the receipt OK will be sent back
from the pump. Inadmissible commands are answered by a
question mark “?”. Each command and each answer must be
confirmed using (=<ENTER>)
The flow rate will be adjusted by the command Fxxxxx. Here is
xxxxx a 5-digit number (representing the flow rate in µl in ASCII
code using the numerals 0 to 9. The permissible range depends
on the pump head and the corresponding internal setting:
10 ml pump head: 0 up to 9990
50 ml pump head: 0 up to 50000
If the selected flow rate lies outside these limits, the command will
be ignored and the last entered flow rate will be maintained.
Controlling the pump via the serial interface enables a flow rate
selection resolution of 1µl/min, i.e. better than it can be achieved
via the keypad. Please keep in mind that this resolution cannot be
shown in the display.
The following Table 2 gives a communication example for the
10 ml pump head.
Table 2
Input Reply Description
F200 OK
Set the flow rate to 200 µl/min Command
correctly understood and executed
F2200 OK
Set the flow rate to 2200 µl/min Command
correctly understood and executed
F22000 ?
Set the flow rate to 22000 µl/min
Command not understood. Flow rate
remains at 2200 µl/min
↵

External control 15
Other commands permissible via RS-232 interface to the HPLC
pump K-120:
M1 Starts the pump, using the currently selected flow rate
Reply : MOTOR_ON
M0 Stops the pump
Reply : MOTOR_OFF
S0 Permits either manual control via the keypad or serial control
Reply : OK
S1 Control is only possible via the serial interface. Only the
STOP key is still active.
Reply : OK
S? Pump status inquiry
Two bytes will be sent back in binary form. The first is the
status byte and shows the motor status in bit 4 (1=ON;
0=OFF). The second one shows the last error code (0=no
error; 1=motor blocked; 2=stop via the keypad), which will
then automatically deleted.
F? Current flow rate inquiry
Reply: Fxxxxx, where xxxxx indicates the flow rate in µl.
T? Pump model inquiry
16 characters will be sent back showing the description
e.g. KNAUER MICRO PUMP
V? Program version inquiry
Reply e.g.: V3.1
If using serial control, the pump sends the following messages to
the PC:
OK The last command was successfully executed
? The last command could not be understood and/or
executed.
HThe pump was stopped either due to an external stop
signal being activated while the pump was running or an
attempt was made to start the pump via the keypad while
the stop signal was still active. In both cases the pump
remains halted (HOLD)
RRemoval of an external stop signal
E1 Error message concerning a motor blockage
E2 Error message if an attempt was made to stop the pump
manually via the keypad, while the serial control is
switched on.

16 Maintenance by the user
Maintenance by the user
Only the pump heads are subject for maintenance. Both pump
heads (10ml and 50ml) differ only in some sizes. Therefore the
descriptions are valid for both of them. If you should use some
older pump head versions (stainless steel or PEEK), please
contact our service division to get the corresponding instructions.
Piston backflushing
Piston backflushing removes traces of salt and other
decontaminates from the backside of the pistons.
If you use saline solvents or buffer solution we highly recommend
that you continuously backflush in order to prevent crystallization
which can damage your piston seals.
SOP 5 Piston backflushing
1. Push a 1/16 ID tube onto both flushing opening, see Piston
backflushing capillaries, item 3.2 in Fig. 2 on page 7.
2. Place the low end of the tubing in a flask.
3. Fill the syringe with rinsing liquid.
4. Connect the syringe with the tubing.
5. Press liquid through the pump head, until it flows without any
air bubbles into the container.
6. Remove tubings from flush opening.
We recommend connecting both flush openings with a tubing
to prevent vaporization of solvents and drying out of the
piston chamber.
If you want operation with continuous backflushing you can attach
two containers of rinsing liquid instead of the priming syringe. The
containers should be positioned that one container is located
higher than the other, thus ensuring liquid flow through the pump
head without any assistance.
Removing the pump head
For exchange of the pump head, or for disassembling it in order to
clean valves or replace piston seals, piston rods etc.
SOP 6 Removing the pump head
1. Purge the pump head with a suitable cleaning agent and
then with distilled water.
If organic solvents remain in the pump head, danger of skin
irritation may exist.
2. Loosen the eluent outlet, item 3.7 in Fig. 2 on page 7 and
the fittings at valve housing inlet, item 3.6

Maintenance by the user 17
3. Use a hexagonal spanner no. 3 (3mm) to loosen just two
diagonally opposed head set screws, item 3.3. Remove the
screws.
4. Loosen the two remaining screws carefully, alternating from
one to the other, approx. half a turn. This prevents the pump
head from tilting and becoming damaged.
5. Once the spring tension has been reduced, hold the pump
head firmly in one hand while removing the screws
completely with the other hand.
6. Remove the pump head carefully.
Removing and checking piston rods
SOP 7 Removing and checking piston rods
1. Remove pump head as described in SOP 6 Removing the
pump head. If you only wish to check the piston rods, you
don’t need to disassemble the pump head any further.
2. Any piston rod, item 3.17 in Fig. 9 on page 18, may be
removed using pliers. Take the tip of the piston using the
pliers, and pull it out carefully in a straight line.
If one of the rods is broken, the entire pump head needs to be
checked for damage.
Disassembling the pump head
SOP 8 Disassembling the pump head
All position numbers of the components are related to Fig. 9 on
page 18.
1. Apply SOP “Removing and checking piston rods” on page
17.
2. Loosen the two retaining plate screws, item 3.19 half a turn,
alternating from one to the other to avoid damage the
retaining plate. Because the two screws are very tight, it may
be useful to either clamp the pump head or to press one of
its side surfaces against a table with one hand while
loosening the screws.
3. Unscrew the two screws strictly alternating due to strong
force of the springs, item 3.15 behind the plate, and remove
them.
4. Remove the retaining plate, item 3.18.
5. Remove the spring guide 3.16 and the springs 3.15.
6. Use a SW 5/16 spanner to loosen the spacing bolts, 3.14.
These bolts are seated very tightly. Follow the advice given
in step 3.
7. Remove the pressure plate, 3.13.
8. Remove the pressure discs 3.20 out of the pressure plate
3.13.

18 Maintenance by the user
9. To remove the piston seals 3.11a , the easiest way is to pull
them out using a 4mm gimlet or a screw of corresponding
diameter.
10. The piston seals 3.11 located in the ceramic seal holder 3.12
are to remove in the same manner.
11. To remove the ceramic seal holders from the housing (not
necessary for exchanging the seals), please follow SOP 12
“Cleaning check valves on page 20 to remove the check
valves 3.10 and the distance holders 3.10a.
12. The ceramic seal holders 3.12 can be removed from the
housing 3.4.
3.19
3.18
3.17
3.16
3.15
3.14
3.11a
3.20
3.13
3.21
3.11
3.4
3.12
3.3
3.10
3.10a
3.10a
3.5
3.6
3.22
3.10
3.24
3.23
Fig. 9 Explosion view of the pump head
Table 3 Parts of the pump head
item Description item Description
3.3 Pump head screws 3.15 Springs
3.4 Housing 3.16 Guide for spring
3.5 Bushing, inlet 3.17 Piston rod
3.6 Bushing, outlet 3.18 Retaining plate
3.10 Check valves, inlet and outlet 3.19 Retaining plate screws
3.10a Distance holder 3.20 Pressure disc
3.11 Piston seal, high pressure 3.21 O-ring
3.11a Piston seal, low pressure 3.22 Capillary connection
3.12 Seal holder (ceramics) 3.23 Screw connection of backflush
3.13 Pressure plate 3.24 Capillary of backflush
3.14 Spacing bolts

Maintenance by the user 19
SOP 9 Assembling the pump head
All positions of components refer to Fig. 9 on page 18. and Fig. 10.
1. Always exchange the piston seals item 3.11 and 3.11a after
disassembly of the pump head and the O-rings, item 3.21
only if nescessary.
3.4
3.20
3.13
3.12
plane areas
180°
180°
3.11 3.11a
3.4 housing 3.13 pressure plate
3.11 piston seal 3.11a piston seal
3.12 seal holder (ceramics) 3.20 pressure disc
Fig. 10 Parts of the opened pump head
2. If you have removed the ceramic seal holder out of the
housing, replace them very carefully with the plane sides
faced together. Otherwise the seal holders cannot be
replaced without damaging them.
3. With the open side facing downwards press the new piston
seals 3.11 into the ceramic seal holder carefully. Make sure
to keep it straight.
4. Lock the ceramic seal holder in place by attaching the check
valves 3.10 and distance holder 3.10a according to SOP 12
“Cleaning check valves“ on page 20.
5. Place the new O-rings 3.21 in the inner side of the pressure
plate 3.13.
6. Install the pressure plate, item 3.13. Take care on the
orientation of housing and pressure plate. Using the SW
5/16 spanner, tighten the spacing bolts, 3.14 firmly.
7. With the open side facing downwards carefully press the
new piston seals 3.11a into the spaces of the pressure plate,
making sure to keep it straight.
8. Cover the seals with the pressure discs 3.20.
9. Install the two guides for spring, 3.16 and the springs, 3.15.
10. Install the retaining plate, 3.18.
11. Insert and tighten the two screws 3.19 strictly alternating due
to strong force of the springs, 3.15 behind the plate.
12. Insert the piston rods 3.17 carefully without bending or
quenching the rods.
13. The spacing bolts, item 3.14 and the retaining plate screws,
item 3.19 must be tightened to be seated as securely as
before.

20 Maintenance by the user
SOP 10 Installing the pump head
1. Make sure that the pump head is properly assembled,
especially check step 13 of the SOP 9 “Assembling the
pump head”.
2. Position the head in a straight line onto the pump housing.
3. Tighten all four pump head set screws, item 3.3 a few turns
by hand.
4. Alternating from one to the next, tighten two diagonally
opposed screws half a turn at a time, until the pump head is
correctly seated.
5. Tighten the two remaining screws. Make sure that all four
pump head set screws, item 3.3 are securely tightened.
6. Connect the solvent tubings according to SOP 3
“Connection of eluent tubings” on page 11.
Check valves
If check valves are contaminated they will no longer open and
close correctly. You can remove the check valves for cleaning
purposes from the pump head. Disassemble them according to the
following instructions.
SOP 11 Replacing check valves
1. Remove the connection to the solvent reservoir.
2. Remove the bushing on the inlet side 3.5. The lower check
valve 3.10 can now be removed together with the bushing.
3. Remove the complete capillary connection 3.22 between the
two pump chambers. Loosen the screw fittings alternating, to
avoid bending the capillary.
4. Remove the bushing from the outlet side 3.6.
5. Remove the upper check valve 3.10 using a pair of
tweezers.
SOP 12 Cleaning check valves
1. Place the valve in a suitable cleaning solution. Use an
ultrasonic bath to clean the valve. If malfunction persists,
use steps 2…5 of this SOP
2. Using a knife or similar, remove the valves seals from the
housing carefully.
3. Remove the individual components by gently tapping the
housing on the table
Valve ball and seating are adjusted in pairs. An exchange of
these parts leads to malfunction of the check valve. Therefore
take care, that any exchange will be avoided, when cleaning
more than one check valves simultaneously.
4. Clean the individual parts. We recommend an ultrasonic
bath.