9
It is important that a pump should never be subjected to thermal or
pressure shock. The liquid should therefore be allowed to flow into
the casing slowly. A centrifugal pump should never be started until
all the parts are up to the temperature of the liquid to be pumped.
If the pump is equipped with cooling water piping this should be
turned on before filling the pump.
FILLING
WARNING:
Before filling the pump with liquid, check to see that all possible leak
locations are sealed. See that the point where the pump shaft enters
the pressure containing cavity is sealed. Normally this sealing is
accomplished with shaft packing or a mechanical face seal. See that
all of the connections into the pressure containing cavity are sealed
or connected to a related piping system that also has all possible
leak paths sealed. Do not plug unused jacket cavities, as this could
develop dangerous pressure build-up. Use a wrench on all bolted
joints to apply torque to assure that all gaskets are sealed in a tight
joint. Check to see that all threaded pipe connections are also tight
enough to seal the Liquid pressure that will be applied when the sys-
tem is started.
When the source of liquid supplied to the pump is below atmos-
pheric pressure or located below the pump, the pump must be
primed prior to start up. The priming may be ac complished in any
of several ways, three of which are listed.
1) An exhauster may be connected to the discharge piping
between the pump and the discharge shut-off valve. With the
discharge shut-off valve closed and the suction valve open, the
air can be exhausted from the pump and piping.
2) With a foot valve installed in the suction piping, the pump may
be filled with liquid introduced somewhere above the pump in
the discharge line. The seal chamber should be vented to
allow complete filling. A foot valve may create extensive losses
and should be taken into consideration in calculating the avail-
able NPSH.
3) A vacuum pump (preferably a wet vacuum pump) may be
used for evacuating air from the pump and piping. The
vacuum pump should be connected as is the exhauster
covered in No. 1.
When the source of liquid supplied to the pump is above atmospher-
ic pressure or above the pump centerline, the pump may be filled by
venting through a bleed off line to atmosphere or back to the pump
suction source.
It Is most Important to check the direction of rotation of the pump
before allowing the pump to come up to speed.
The pump was
shipped with the coupling spacer not installed to allow alignment
and motor rotation direction check. If, however, someone installed
this spacer assembly, lock-out the power to the driver (motor, turbine,
engine, etc.), and remove the spacer assembly at this time. To check
rotation direction, push the starting button and instantly push the stop
button. This will allow the motor to turn over a few revolutions and
the direction of rotation to be observed. A direction of rotation arrow
is shown on the front of the pump casing. If rotation is incorrect,
change the wiring connections and recheck rotation.
Operating the
pump in reverse rotation may cause extensive damage.
WARNING:
Lock-out the power to the driver (motor, turbine, engine, etc.)
Install the shaft coupling spacer assembly. Be sure that you install all
the retaining devices and bolts and that they are tight. Read and
comply with the coupling manufacturers instructions. Personal injury,
death, and/or equipment damage could occur if the coupling spacer
is not properly installed. Remove all debris and tools from the area
near the shafts and the shaft coupling. Do this to assure that nothing
is caught and thrown by the rotating parts when the pump is start-
ed. Bolt the coupling guard securely into place, checking to assure
that it is not contacting any parts that will rotate when the pump is
started.
OPERATING
WARNING:
Before starting the unit, see that all personnel are a safe distance
away from all possible hazards, that all sub-systems are connected
and operating, that all debris has been removed, that the shaft cou-
pling guard is securely in place, and that the pump is full of liquid.
Do not operate this pump at shut-off (no flow) as an explosion may
result. This can occur with any liquid, even
“
cold water
”
. Personal
injury, death, equipment damage, and/or loss of product
(pumpage) is likely to occur. If your system is operated where it is
possible for all outlets of the discharge from the pump to be closed
while the pump is still operating, a modification of the system needs
to be made to assure a continual flow of pumpage through the
pump. NOTE: Some people have a belief that a bypass line from the
discharge side of the pump to the suction side of the pump will
relieve this problem, this is “NOT TRUE”; DO NOT ATTEMPT THIS.
WARNING:
Do not operate a pump at a low flow condition, unless provision has
been made to prevent dangerous heat build up within the pump
casing. The liquid in the pump will heat up and this may result in
high pressure in the pump in a short time. Such pressure may result
in a rupture of the pressure-containing parts and cause severe haz-
ard to personnel and/or damage to the system.
A centrifugal pump should never be run without liquid In the casing.
Extensive damage may result, particularly to the mechanical seal or
compression packing. When the pump is equipped with a mechani-
cal seal, vent the pump seal chamber through the seal connection to
provide lubrica tion to the mechanical seal faces.
A centrifugal pump should be started with the suction valve open
and the discharge valve opened a slight amount.
As soon as the pump is up to speed, the discharge valve must be
opened slowly. A centrifugal pump cannot be operated with the
discharge valve closed without heating up dangerously. During the
first several minutes of operating watch the pump carefully for
overheating, vibration, and other abnormal conditions. If trouble
develops, stop pump at once and correct the problem.
STARTING THE PUMP
