Haskel 8 Serie Instructions De Fonctionnement Et D'entretien page 3

8" Drive Liquid Pumps • OM-LP-800F
NOTE: Each plunger or rod has a dual seal design with a small vent between to dissipate minor air or
liquid leakage. Models beginning with "8D" have additional distance piece separation to preclude any
possibility of liquid leakage reaching the drive section.
The life of the pumping section depends on the cleanliness of the liquid supply. Therefore, reasonable
filtration is suggested at the liquid inlet. 100 mesh screen is normally adequate. Fine micronic filtration is
not recommended.
Over the life of the moving parts, some migration of wear particles into the liquid output should be
expected.
2.3.1 CYCLING RATES
If there is an ample volume of drive air or gas available at the installation (100 scfm or more), the drive will
tend to cycle at an excessive rate if the liquid output resistance is low. This can be seen in the catalog on
the performance curve charts for each model. Note the shaded area on each chart. Sustained operation
in this area is not recommended. It can result in premature maintenance and probably objectionable noise
and vibration. Cycling rate can be retarded by throttling the drive air or gas.
2.3.2 ICE FORMATION IN DRIVE SECTION
Sustained operation against a load using 90 psi or more drive can drop the temperature of the drive
section to well below freezing. If this is also below the dew point of the drive air or gas, ice will form inside
the drive and the valve and slow or stop it completely. If very dry drive air or gas is used (dew point below
0° F) the ice will probably not form inside but the ambient humidity will form heavy frost on the outside of
the drive and mufflers. No harm results, although drive slow down may be noticed due to frost in the slots
in the mufflers. The best defense against freeze-up is to review the application to see if sustained
operation at high output load can be avoided, possibly by tying in a mechanically driven pump to handle
the high flow requirement and sequencing in the air driven pump for the high pressure, variable flow,
start/stop requirements for which it has been designed. Antifreeze injectors on the drive air input are of
questionable value due to the volume needed, the contaminated exhaust created and the potential
swelling of dynamic o-rings.
Air drive heating can help but the power required for the airflow rates encountered will probably be
unacceptable.
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