9
STARTING
During the pump start-up phase, special care should be taken and the following points should be followed in order to avoid expensive
problems. See the respective manuals of each model pump for the recommended spare parts for start-up.
Before starting the pump, check the following:
❑
Check that all safety devices are in operation.
❑
Fill the pump. When the pump is empty (completely dry) it should
NOT
be started, except in
exceptional cases
but only for a few seconds.
Otherwise, there is a very high risk of mechanical damage, which can even be quite severe.
❑
When full, the pump should be well bled. The pump casing is usually constructed to be self-breathing. Therefore, it is important to check
that there are no air bubbles within the piping, especially in the
suction line
.
❑
Check the alignment of the pump, gear box (if fitted) and motor.
❑
Check that the filter and pipework are free from welding scales and metal shreds.
❑
Check that the joints are well tightened.
Check that the piping does not weigh too heavily on the pump casing. See the maximum permissible nozzle loads in the first section of
the Technical Manual. If the liquid can reach high temperatures, check that expansion joints are fitted in the pipework. Check the electrical
connections and rating of the motor and check its rotational direction.
❑
Ensure that the direction of rotation of the pump is correct. The control of the rotation direction of the pumps installed on a base with a B3
type motor should be carried out by uncoupling the motor from the pump by removing the appropriate spacer of the two half-joints. For
pumps close coupled to a B5 and/or B14 type motor, the rotation direction should
ONLY
be checked when there is liquid in the pump.
❑
If a by-pass relief valve is fitted, it must be mounted correctly.
❑
The inside of the tube should not be dry, especially if it is to self-prime. Fill or wet the internal parts with oil, the liquid to be pumped or a
liquid that is compatible with the liquid pumped.
❑
Check that the pump shaft is free to rotate. Prior to start-up and with the certainty that there is liquid in the pump, check that the pump-
motor coupling can be hand turned freely and that the pump/motor alignment is correct.
❑
During assembly, the pumps are protected with a passivating oily liquid. If this liquid is not compatible with the liquid pumped, the pump
must be disassembled and cleaned (see point 8.1)
❑
Fit the connections for the pressure and vacuum gauges.
❑
Do not use V series gear pumps for tests with water.
❑
Prior to pumping liquids that are different to those for which the pump is intended, consult the Technical Manual and other specific model
manuals or consult the Sales Department.
❑
Check that all of the valves are open. The pump must be started with the
suction and discharge valves completely open.
❑
For pumps with heating jackets which are destined for pumping liquids that can solidify, it is recommended to heat the pump by means of
the appropriate heating chambers for at least two hours prior to performing the start-up procedure.
❑
To check the correct operation of the pump at the required duty point, it is absolutely necessary to install a pressure gauge on the delivery
line upstream of the control valve. In certain cases it is advisable to install a vacuum/pressure gauge on the suction line.
❑
By means of the pressure gauge and, if fitted, the flow meter, check that the pump is operating within the correct range with respect to the
duty point and the performance curve.
❑
After starting the pump, check that the liquid has entered is and that the pump is operating correctly. If, after 1 minute, the pump is still
running dry, stop the pump and check the pump and pipework following the indications of point 10.1 described below.
For any problems, doubts or information, VARISCO technicians are at your complete disposal. Do not hesitate to contact us in
order to avoid operations which could compromise the correct operation of the pump.
10 OPERATING PROBLEMS
If operating problems are encountered either upon start-up or after the pump has been running for some time, proceed as follows prior to
intervening onto the pump:
❑
ensure that there is no pressure within the pump.
❑
ensure that the pump does not start-up again by mistake or through automatic controls (disconnect the power supply to the motor).
❑
read the following instructions carefully.
10.1 The pump fails to prime
❑
Incorrect rotational direction.
❑
No liquid in the pump to create a seal between the gears and the casing. The suction gauge hardly moves or else oscillates. If the pump
is required to self-prime at every start-up and has difficulty in priming, it is advisable to fit a
“
goose-neck
”
or foot valve in the suction line
in order to ensure that there is always liquid in the pump.
❑
Suction valve closed, suction line or filter clogged. The vacuum gauge reading is high.
❑
It is not easy to identify the leaks in the suction pipework. Listen for the characteristic hiss of the air leaks near the joints.
❑
The pump is not able to expel the air through the discharge line. Check that all of the valves are open; if necessary, bleed the delivery pipe.
❑
Excessive suction lift, especially when pumping liquid with high vapour pressure. Install the pump on flooded suction.
❑
Low rotational speed.
❑
By-pass relief valve blocked in the open position by impurities.
❑
Empty suction tank.
❑
Pump cover installed in the wrong position.
7
