Pentax HP Manual Del Usuario página 56

5. WORKING AND USAGE
STOP
The pump must be stopped by switching off the electric supply to the motor.
Centrifugal pumps can be stopped with the gate valve in the output line ei-
ther open, or closed.
To avoid water hammer, a none return valve can be fitted in the delivery line.
The eventual cooling must be stopped only after pump has reached room
temperature. (fig.33).
3.
In case of long pump stoppages, to avoid the risk of freezing
during the cold season or prevent corrosion due to the possible
chemical alteration of any stagnating liquid in the pump, empty
out the pump completely of any remaining fluid.
5.2 • SETTING AND CHECK OF OPERATION
In detail a list of the main checks the user must carry out after pump starting.
For problems and solutions please refer to chapter 7 "PROBLEMS, CAUSES,
SOLUTIONS".
HEAD
Pump capacity depends on head according to the operating curve.
After starting, the pump head has to be the same as the head reported on the
label.
For calculating, read the values shown by the delivery pressure gauge and by
the suction vacuum meter and use the following formula:
H =
H = differential head (m)
Y = specific weight at pumping temperature (Kg/dm3)
Pm = delivery pressure
Pa = suction pressure
When required pump head is lower than the rated pump pressure, slowly close
gate valve in the delivery line to obtain the required operating pressure.
Load losses higher than those foreseen on project, cause a pump head higher
than the nominal one. Modify the installation to reduce the losses and reach the
correct total head.
VIBRATIONS/NOISE
The pump should work at it's rated flow & pressure, without undue
noise or vibration. In the negative, stop the pump and investigate.
TEMPERATURE OF THE ROLLING BEARINGS
The temperature of the rolling bearings, which rotate at 3000 rpm, can easily exceed 80° C. It does not suffice to control the
Temperature manually
- The bearings only reach a normal temperature after operating for a few hours.
- When commissioning new pumps, the temperature can exceed 95 ° C. It slowly starts to
subside after about 2- 3 hours of operation and reaches a constant value after about a week.
- The cause that lies behind an increase in temperature can be verified by dismantling the
bearings or the hydraulics. However, if the temperature exceeds 100 ° C when commissioning takes pl ace, the
pump must be stopped and the inspections descrive in chap.7, point 6 must be carried out.
10,2 (Pm-Pa)
Y
21
°C
Fig.33