Operating manual for centrifugal pumps AT - TB… - MC… - TC… - TMA
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CHECK PUMP-MOTOR COUPLING ALIGNMENT!
This must be done prior to the first start-up and before every start-up if pump or motor has been removed from
the installation for maintenance or other reasons. See chapter 8.2.
11.1 - START-UP
Never run the pump when it is dry!
Before starting-up verify that all auxiliary supplies are in place, ready to be used and, where necessary, they have been
correctly opened. (Example: seal or packing flushing, pressurising buffer liquid to “back to back” double mechanical seals,
etc.). Make sure the pump and motor bearings have been properly lubricated and oil levels are correct.
If necessary oil topping should be done through the proper connections (see fig. 20-21-22-23) and with recommended
lubricants (see chapter 13). If the liquid to be handled is at dangerous high temperatures it is required to insulate the
pump and the piping to prevent direct contact, the pump should also be protected against thermal shocks by insulation,
preheating, etc.
Prior to starting, the suction piping and the pump must be filled with the liquid to be lifted; for this purpose there are three
types of installations to be identified:
CAUTION!
Possible contact with hazardous media, cold or warm, and pump surfaces, cold or warm. During the following
operations it is particularly important to avoid contact and/or inhale of possible spilled liquid (vapour): therefore
all safety precautions must be taken. Operate only provided with apposite protective devices.
For this purpose there are three types of installations to be identified:
11.1.1 - Submersed pump (vertical design)
Pump filling is not applicable.
11.1.2 - Pump with flooded suction
Close the valve at pump discharge side, fully open the valve at pump suction side and the vent valve including any
breather valve on the stuffing box.
Pump series TCD are fitted with a vent cock (see fig. 10B) which should be open to prevent forming air pockets
in the mechanical seal chamber.
CAUTION!
Possible contact with warm media and warm surfaces. Be sure to do this only when the spilled thermal oil is at
ambient temperature. Operate only provided with apposite protective devices.
When the thermal fluid exits the air cock without any air or gas bubbles, even after turning the pump rotor it means that
the whole pump is full of liquid, therefore close the air cock.
11.1.3 - Pump with suction lift (from well)
In this case the pump must be primed: fully open the isolating valve in suction piping.
If the pump is self-priming and it has been previously filled with liquid, there will be no problems, because the pump will
be able to prime itself and lift the liquid as soon as it starts operating.
If the pump is not self-priming, but the suction piping is fitted with a foot valve, the suction piping and the pump can be
filled with liquid by opening the valve at the discharge side (provided the discharge piping is full of liquid) or fill the pump
body as well as suction piping, with the liquid to be pumped, through the vent valve.
For non self-priming pumps with the suction piping not having a foot valve, the suction piping and the pump can be filled
with liquid by hooking-up the vent valve to a vacuum line and keeping closed the valve at the discharge side of the pump:
when the liquid exits the vent valve it means that the pump and suction piping are completely full of liquid.
At this point close the vent valve and the vacuum line.
Check the position and/or control the opening of the minimum flow valve, flushing lines and/or auxiliary supply lines.
After the pump and its suction line is full of liquid the pump should be started. In this regard there are two possible cases:
11.1.4 – Start-up a pump without back pressure at discharge side
For centrifugal pumps type MC... - TC... - TMA motor must be started with discharge valve closed.
When the motor has reached full speed, the discharge valve can be opened until the required differential pressure is
reached (CAUTION: do not operate the pump with closed discharge piping for an extended period of time, to avoid
overheating problems previously discussed).
For self-priming pumps type AT - TBH - TBA all valves in suction and discharge piping must be fully open before starting
the motor. After the motor has been started the discharge valve can be throttled to build up the expected pressure.
(It is possible to start these pumps with the discharge valve at the closed position but, in this case, there will be maximum
power consumption at start -up).
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