Xylem P81875F Series HSC and HSC-S Centrifugal Pump - Manual (Page 12)

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16. Mechanical Seals
Mechanical seals are preferred over packing on some applica-
tions because of better sealing qualities and longer service-
ability. Leakage is eliminated when a seal is properly installed,
and normal life is much greater than that of packing on similar
applications.
Single Mechanical Seal
Pumps containing single mechanical seals normally utilize
the pumped liquid to lubricate the seal faces. This method is
preferred when the pumped liquid is neither abrasive nor
corrosive.
B. OPERATION
1. Pre-start Checks
Before initial start of the pump, make the following
inspections:
a. Check alignment between pump and motor.
b. Check all connections to motor and starting device with
wiring diagram. Check voltage, phase, and frequency on
motor nameplate with line circuit.
c. Check suction and discharge piping and pressure gauges
for proper operation.
d. Check impeller adjustment, see specific section for proper
adjustment.
e. Turn rotating element by hand to assure that it rotates
freely.
f. Check driver lubrication.
g. Assure that pump bearings are properly lubricated.
h. Assure that coupling is properly lubricated, if required.
i. Assure that pump is full of liquid (See 2. Priming) and all
valves are properly set and operational, with the discharge
valve closed, and the suction valve open.
j. Check rotation. Be sure that the drive operates in the direc-
tion indicated by the arrow on the pump casing as serious
damage can result if the pump is operated with incorrect
rotation. Check rotation each time the motor leads have
been disconnected.
2. Priming
If the pump is installed with a positive head on the suction, it
can be primed by opening the suction and vent valve and
allowing the liquid to enter the casing.
If the pump is installed with a suction lift, priming must be
done by other methods such as foot valves, ejectors, or by
manually filling the casing and suction line.
3. Starting
a. Close drain valves and valve in discharge line.
b. Open fully all valves in the suction line.
c. Prime the pump.
NOTE: If the pump does not prime properly, or loses prime
during start-up, it should be shutdown and the condition
corrected before the procedure is repeated.
d. When the pump is operating at full speed, open the dis-
charge valve slowly. This should be done promptly after
start-up to prevent damage to pump by operating at zero
flow.
4. Operating Checks
a. Check the pump and piping to assure that there are no
leaks.
b. Check and record pressure gauge readings for future
reference.
c. Check and record voltage, amperage per phase, and kw if
an indicating wattmeter is available.
d. Check bearings for lubrication and temperature. Normal
temperature is 180° maximum.
e. Make all pump output adjustments with the discharge line.
5. Freezing Protection
Pumps that are shut down during freezing conditions should
be protected by one of the following methods.
a. Drain the pump; remove all liquids from the casing.
b. Keep fluid moving in the pump and insulate or heat the
pump to prevent freezing.
WARNING: Rotating Components Hazard
Do not operate pump without all guards in place.
Failure to follow these instructions could result in serious
personal injury or death and property damage.
WARNING: Rotating Components Hazard
Do not operate pump without all guards in place.
Failure to follow these instructions could result in serious
personal injury or death and property damage.
CAUTION: Cavitation Damage Hazard
Do not throttle the suction line to adjust the pump
output. Failure to follow these instructions could result in
property damage and/or moderate personal injury.
CAUTION: Bearing/Seal Damage Hazard
Do not let heated pump temperature rise above
150°F. Failure to follow these instructions could result in
property damage and/or moderate personal injury.
CAUTION: Seal Damage Hazard
Do not run pump dry, seal damage may occur.
Failure to follow these instructions could result in property
damage and/or moderate personal injury.