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auxiliary block to the peak recording the work of working block. It is indicated damage of inlet
check valve.
P
RESSURE
R
ECORD IN
E
COMAC
–
D
AMAGED
C
HECK
V
ALVE
P
re
ss
u
re
[
M
P
a]
19.7
19.8
19.9
20.0
20.1
20.2
20.3
Time [min]
1.2
1.4
1.6
1.8
Flowrate 1 ml/min, 50% isopropanol s 50 % distilled water, compensation
OFF
In case of confusion which check valve is damaged. Proceed as follows. At first, clean both
). Verify the record. If it is not right, the first replace inlet check valve. After
replacement, check the record. If the record is ok, original inlet check valve was ok. Replace the
outlet check valve and check the record.
Damaged Seals
Caution.
Minor seal damages are difficult to identify. It is manifested by high
pulsation during high flowrates 8 - 10 ml/min (7 MPa and more) and minor
leakage to piston backwash system. However, pressure record is ok during
low flowrate (1 ml/min) and seals can still be used.
In case of confusion damage of seals. Check the tightness of the pump. The pump outlet is
closed with a plug. Then pumping starts at the flowrate of 0.5 ml/min. Continue to pressure rise of
approximately 35 MPa. Pumping stops and pressure value is recorded after 1 min. The pressure
must not fall below 15 MPa. If it falls, check the screws in block heads and closure of purge/degass
valve. Make test of tightness again. If pressure falls after limit, replace seals in the pumping heads.
When seals are damaged seriously, liquid is visibly leaking from pump blocks.
11. M
AINTENANCE
11.1. Periods
Minimal period for check valve and seal exchange is one year.
This period may be
shorter if there are used buffers, high pressure/flow rate, aggressive solvents, everyday use or
other aggravating conditions. In case of such difficult environment it is recommended to exchange
the check valves and seals every 6 months.
