HP 8-UB-1 - Manual (Page 19)

UB USER INSTRUCTIONS ENGLISH 71569247 07-04
Page 19 of 32
®
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) adjacent to
the bearing and the ambient temperature (ta)
• Estimate the likely maximum ambient
temperature (tb)
• Set the alarm at (t+tb-ta+5) °C [(t+tb-ta+10) °F]
and the trip at 100 °C (212 °F) for oil lubrication
and 105 °C (220 °F) for grease lubrication
It is important, particularly with grease lubrication, 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 rise should then remain constant or
marginally reduce with time. (Refer to section 6.2.3.1
for further information.)
5.7.5 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 adjacent to the
pump bearings at regular intervals will then show any
deterioration in pump or system operating conditions.
Vibration velocity – unfiltered
mm/s (in./s) r.m.s.
Horizontal
pumps
Vertical
pumps
Normal N ≤ 5.6 (0.22) ≤ 7.1 (0.28)
Alarm N x 1.25 ≤ 7.1 (0.28) ≤ 9.0 (0.35)
Shutdown trip N x 2.0 ≤ 11.2 (0.44) ≤ 14.2 (0.56)
5.7.6 Stop/start frequency
Pump sets are normally suitable for the number of
equally spaced stop/starts per hour shown in the
table below. Check actual 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 90 (120) 10
Above 90 (120) 6
Where duty and standby pumps are installed it is
recommended that they are run alternately every
week.
5.8 Stopping and shutdown
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.