Hydrotech C, C PLUS, A PLUS, E, E-DC and E PLUS Series PULSAtron - Manual (Page 17)

5.5.3 4-20mA DC INPUT FUNCTION cont'd.
• The signal cord polarity is:
Black
= Common
White = Positive
Wrong polarity can result in excess flow.
ƒ Signal input impedance is 124 ohms.
ƒ Remove cap from pump socket labeled 4-20 mA, use polarized cord supplied
with pump to connect control circuit to pump. Plug cord into pump socket
labeled 4-20 mA.
6.0 MAINTENANCE
Before performing any maintenance or repairs on chemical
metering pumps, be sure to disconnect all electrical connec-
tions, insure that all pressure valves are shut off and pressure
in the pump and lines has been bled off.
Always wear protective clothing, gloves and safety glasses when
performing any maintenance or repairs on chemical metering
pumps.
6.1 ROUTINE MAINTENANCE
• Routinely check the physical operating condition of the pump. Look for the
presence of any abnormal noise, excessive vibration, low flow and pressure
output or high temperatures [when running constantly at maximum stroke
rate, the pump housing temperature can be up to 160
°F (70°C)].
• For optimum performance, cartridge valves should be changed every 6-12
months. Depending on the application, more frequent changes may be
required. Actual operating experience is the best guide in this situation.
• Repeated short-term deterioration of valve seats and balls usually indicates
a need to review the suitability of wetted materials selected for the applica-
tion. Contact the supplier for guidance.
• Check for leaks around fitting or as a result of deteriorating tubing e.g. when
standard white translucent discharge tubing is exposed to direct sunlight.
Take appropriate action to correct leak by tightening fittings or replacing
components.
• Keep the pump free of dirt and debris as this provides insulation and can lead
to excessive pump temperatures.
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