Flowserve ESP2 - Manual (Page 33)

ESP2 USER INSTRUCTIONS ENGLISH PCN-(71569292) 4-12
Page 33 of 64
f) Turn on other auxiliary lines (if required) such as
stuffing box injection or mechanical seal flush.
g) Start the driver. If other than motor drive, bring the
pump up to speed quickly.
h) As soon as the pump is up to rated speed, open the
discharge valve slowly, to desired capacity or
pressure keeping in mind the minimum
continuous flow listed in section 3.4.
i) Check all joints and mechanical seal (if
furnished) for leakage.
j) If packing is furnished, adjust the packing gland
and flush flow.
k) Check for excessive vibration.
l) Monitor bearing temperature until it stabilizes.
It is important that the discharge valve be
opened within a short interval after starting the driver.
Failure to do this could cause a dangerous build up of
heat, and possibly an explosion.
5.8 Running or operation
5.8.1 Operating Checks
Costly shut-downs will be avoided by making routine
checks on pump operation.
a)
Check to see if liquid is being discharged. A
discharge pressure gauge is an easy way to
check whether or not the liquid is being pumped.
If, at any time, the gauge should drop to zero, or
register an abnormally high pressure, shut down
the pump immediately.
b) Observe pump for any abnormal noise or
vibration. Especially check for any CHANGE in
pump noise or vibration.
c) Bearing lubricating liquid or grease and sealing
and cooling liquid flows, should be checked
frequently.
5.8.2 Minimum continuous flow
Minimum continuous stable flow is the lowest flow at
which the pump can operate and still meet the bearing
life, shaft deflection and bearing housing vibration limits
documented in the latest version of ASME B73.1M.
Pumps may be operated at lower flows, but it must be
recognized that the pump may exceed one or more of
these limits. For example, vibration may exceed the
limit set by the ASME standard. The size of the pump,
the energy absorbed, and the liquid pumped are some
of the considerations in determining the minimum
continuous flow (MCF).
The minimum continuous flow (capacity) is established
as a percentage of the best efficiency point (BEP). (See
section 3.4.1.)
5.8.3 Minimum thermal flow
All ESP pumps also have a minimum thermal flow.
This is defined as the minimum flow that will not
cause an excessive temperature rise. Minimum
thermal flow is application dependent.
Do not operate the pump below
minimum thermal flow, as this could cause an excessive
temperature rise. Contact a Flowserve sales engineer
for determination of minimum thermal flow.
Avoid running a centrifugal pump at drastically reduced
capacities or with discharge valve closed for extended
periods of time. This can cause severe temperature
rise and the liquid in the pump may reach its boiling
point. If this occurs, the mechanical seal will be
exposed to vapor, with no lubrication, and may score or
seize to the stationary parts. Continued running under
these conditions when the suction valve is also closed
can create an explosive condition due to the confined
vapor at high pressure and temperature.
Thermostats may be used to safeguard against
overheating by shutting down the pump at a
predetermined temperature.
Safeguards should also be taken against possible
operation with a closed discharge valve, such as
installing a bypass back to the suction source. The size
of the bypass line and the required bypass flow rate is a
function of the input horsepower and the allowable
temperature rise. The bypass line must always enter the
sump (pit) at a point below the liquid level to prevent air
entrainment.
5.8.4 Reduced head
Note that when discharge head drops, the pump’s
flow rate usually increases rapidly. Check motor for
temperature rise as this may cause overload. If
overloading occurs, throttle the discharge.
5.8.5 Surging condition
A rapidly closing discharge valve can cause a
damaging pressure surge. A dampening
arrangement should be provided in the piping.
5.8.6 Operation in sub-freezing conditions
When using the pump in sub-freezing conditions
where the pump is periodically idle, the pump should
be properly drained or protected with thermal devices
which will keep the liquid in the pump from freezing.
The pump unit must not be operated
above the nameplate conditions. Such operation
could result in unit failure and injury to personnel.