Pd pump Systems neslab p/N 000878 Rev. 08/15/96 Service Manual

Figure 4
Theory of
Operation

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Figure 5

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8
Fluids
This is a list of some typical fluids which may be used in a PD
pump system.
Glycol, ethylene - up to a 50% concentration in water. Labora-
tory or reagent grade is typically used. Automotive antifreeze is
not recommended.
Glycol, propylene - up to a 50% concentration in water. Labora-
tory or reagent grade is typically used. Automotive antifreeze is
not recommended.
Water, deionized - up to a resistivity of 1.8 megohm/cm.
Water, single distilled
Water, tap
Wetted Parts
The following materials are in contact with the circulating fluid in a
PD pump system.
PVC
Copper
Bronze
Brass
Stainless Steel
Teflon® thread sealing tape
Nickel-plated copper
Carbon-graphite pump vanes and liner

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9
Troubleshooting chart - No Flow
Figure 6

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10
Troubleshooting chart: No Flow (continued)
Figure 6a

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Figure 7
Troubleshooting chart: Pump Noise

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12
Troubleshooting chart: Pump Noise (continued)
Figure 7a

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13
Troubleshooting chart: Low Flow and/or Pressure
Figure 8

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14
Leaks
The flange area of the pump has assembly holes at the top and the
bottom. Fluid leaking out of either hole indicates a shaft seal
failure. The seal has a limited ability to seat around imperfections.
If this is a new pump, allow it to run for 24 hours and re-inspect. A
continuous leak will require pump replacement. Field replacement
of the shaft seal is not practical.
Certain fluids will deteriorate the pump shaft seal. Highly deionized
water will leach ions out of the seal material, causing it to lose
flexibility. This will cause leaks. Deionized water must be used with
caution, and with monitoring of the deionization level. See FLUIDS
for further details.