Flowserve WPG IDP - Manual (Page 18)

WPG and WPH USER INSTRUCTIONS ENGLISH 26999969 10-12
Page 18 of 40
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Never run a mechanical seal dry, even
for a short time.
5.7.3 Bearings
If the pumps are working in a potentially
explosive atmosphere monitor temperature and/or
vibration at the bearings.
If bearing temperatures are to be monitored it is
essential that a benchmark temperature is recorded
at the commissioning stage and after the bearing
temperature has stabilized.

Record the bearing temperature (t) and the
ambient temperature (ta)

Estimate the likely maximum ambient
temperature (tb)

Set the alarm at (t+tb-ta+5) º C (t+tb-ta+10) ºF
and the trip at 100 ºC (212 ºF) for oil lubrication
and 105 ºC (220 ºF) for grease lubrication
It is important, to keep a check on bearing
temperatures. After start up the temperature rise
should be gradual, reaching a maximum after
approximately 1.5 to 2 hours. This temperature should
then remain constant or marginally reduce with time.
5.7.4 Normal vibration levels, alarm and trip
For guidance, pumps generally fall under a classification
for rigid support machines within the International
rotating machinery standards and the recommended
maximum levels below are based on those standards.
Alarm and trip values for installed pumps
should be based on the actual measurements (N) taken
on the pump in the fully commissioned as new condition.
Measuring vibration at regular intervals will then show
any deterioration in pump or system operating
conditions.
Vibration velocity –
unfiltered
Horizontal pumps

15 kW mm/sec
(in./sec) r.m.s.
> 15 kW
mm/sec (in./sec)
r.m.s.
Normal N  3.0 (0.12)  4.5 (0.18)
Alarm N x 1.25 
3.8 (0.15)

5.6 (0.22)
Shutdown trip N x 2.0 
6.0 (0.24)

9.0 (0.35)
5.7.5 Stop/start frequency
Pump sets are normally suitable for the number of
equally spaced stop/starts per hour shown in the
table below. Check capability of the driver and
control/starting system before commissioning.
Motor rating kW (hp)
Maximum stop/starts
per hour
Up to 15 (20) 15
Between 15 (20) and 45 (60) 10
Where duty and standby pumps are installed it is
recommended that they are run alternately every week.
5.8 Stopping and shutdown (all series)
a) Close the outlet valve, but ensure
that the pump runs in this condition for no more
than a few seconds.
b) Stop the pump.
c)
Switch off flushing and/or cooling/heating liquid
supplies at a time appropriate to the process.
d) For prolonged shut-downs and
especially when ambient temperatures are likely
to drop below freezing point, the pump and any
cooling and flushing arrangements must be
drained or otherwise protected.
5.9 Hydraulic, mechanical and electrical
duty
This product has been supplied to meet the performance
specifications of your purchase order, however it is
understood that during the life of the product these may
change. The following notes may help the user decide
how to evaluate the implications of any change. If in
doubt contact your nearest Flowserve office.
5.9.1 Specific gravity (SG)
Pump capacity and total head in metres (feet) do not
change with SG, however pressure displayed on a
pressure gauge is directly proportional to SG. Power
absorbed is also directly proportional to SG. It is
therefore important to check that any change in SG
will not overload the pump driver or over-pressurize
the pump.
5.9.2 Viscosity
For a given flow rate the total head reduces with
increased viscosity and increases with reduced
viscosity. Also for a given flow rate the power
absorbed increases with increased viscosity, and
reduces with reduced viscosity. It is important that
checks are made with your nearest Flowserve office if
changes in viscosity are planned.
5.9.3 Pump speed
Changing pump speed effects flow, total head, power
absorbed, NPSH
R
, noise and vibration. Flow varies in
direct proportion to pump speed, head varies as speed
ratio squared and power varies as speed ratio cubed.
The new duty, however, will also be dependent on the
system curve. If increasing the speed, it is important
therefore to ensure the maximum pump working
pressure is not exceeded, the driver is not overloaded,
NPSH
A
> NPSH
R
, and that noise and vibration are
within local requirements and regulations.