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8
Maintenance of the double diaphragm pump
8.1 Troubleshooting
Cause:
Suction lift of the system too high
Too high priming pressure on the
suction side of the system
Back pressure of the medium
higher than the air pressure
Compressed air pressure higher
than the back pressure of the
medium
Suction line of too small nominal
width
Maintenance of the double diaphragm pump
User qualification, wait: instructed personnel, see
n
2.2 'Users' qualifications' on page 6
WARNING!
Danger from hazardous substances!
Possible consequence: Fatal or very serious injuries.
Please ensure when handling hazardous substances
that you have read the latest safety data sheets pro‐
vided by the manufacture of the hazardous substance.
The actions required are described in the safety data
sheet. Check the safety data sheet regularly and
replace, if necessary, as the hazard potential of a sub‐
stance can be re-evaluated at any time based on new
findings.
The system operator is responsible for ensuring that
these safety data sheets are available and that they
are kept up to date, as well as for producing an associ‐
ated hazard assessment for the workstations affected.
Before all work
Before all work on the double diaphragm pump, dis‐
connect the double diaphragm pump from the com‐
pressed air supply and the feed and discharge lines,
vent and decontaminate. Always observe the safety
data sheet for the chemicals to be conveyed.
Possible symptoms
Double diaphragm pump does not cycle
n
Double diaphragm pump cycles, but does not pump
n
Double diaphragm pump cycles, but insufficient feed rate
n
Double diaphragm pump cycles irregularly
n
Double diaphragm pump vibrates strongly
n
Measure:
For suction lifts above 6 metres, priming of the pump can in most
cases be induced by pre-filling the pump chambers
If there is a priming pressure of more than 3 metres water column, pro‐
vide a back pressure valve in the air outlet of the double diaphragm
pump
Increase the air inlet pressure to the double diaphragm pump
Adjust the feed air pressure according to the performance curve of the
double diaphragm pump. At high stroke rates, cavitation in the medium
may occur
Observe the recommendations of the dimensioned drawing for the
cross-section of the suction line
Ä Chapter
19
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