10
VM 623.0004 GB/07.00 – Ident–Nr. 550 298
6 Start–up/Shutdown
6.1 Preparation for start–up
6.1.1 Filling the pump with fluid
Prior to initial operation, the screw pump
must be filled with fluid and bled. This at the
same time provides the spindles with the sealing re-
quired for suction.
The pump must not run dry.
Before filling, the operator must ensure
careful and thorough rinsing of the pump if
the fluid to be conveyed is not chemically compatible
with the test medium (see performance test report).
The fluid is filled through a bore hole in the pump casing
or via the pressure pipeline. The pump must be filled
with fluid until the fluid emerges free from air.
In the case of immersion pump aggregates the filling
level must ensure adequate covering of the inlet rim be-
fore and during operation.
During bleeding of the pump and the plant, hazardous
or environmentally harmful fluid and gas emerging
must be safely collected and discharged.
6.1.2 Control of drive motor direction of rotation
The direction of rotation of the motor must match the
direction of rotation arrow on the pump. The motor can
be briefly switched on with the suction and pressure
valves open to check the direction of rotation. If the
direction of rotation is wrong there is no pump suction.
This damages the pump. The direction of rotation of the
three–phase motor can be reversed by swapping any
two phases.
If the direction of rotation is to be checked
before the pump is filled with fluid, the drive
motor must be disconnected from the pump. The pump
must not run dry.
6.2 Start–up
6.2.1 Starting
1. Prior to starting, the stop valves in the suction and
pressure pipelines must be completely opened.
2. Where the pump is fitted with a pressure–relief
valve, it is set on our test panel to respond 10%
above the operating pressure. The opening pres-
sure can be altered within narrow limits by means of
an adjusting screw. The installation of a pressure–
relief valve is always required when an impermissi-
ble pressure rise is possible, due to a stop device or
throttle point in the pressure pipeline for example.
When starting and stopping the pump
under pressure, make sure that the
speed– and viscosity–dependent pressure load is
not exceeded.
If this is not ensured, the pump must be started and
stopped at zero pressure. This also applies to
pumps with speed–controlled drive motors.
3. During starting, a vent valve installed on the outlet
side of the plant must be opened until the air has es-
caped from the suction side of the pump. As soon as
fluid emerges the vent valve can be closed. The
pump is self–priming and is automatically vented
without counter–pressure.
4. The fluid level in the tank must be checked. It must
be ensured that, when the plant is running, the fluid
level in the tank does not fall below the minimum
limit. Top up fluid as necessary.
6.2.2 Drive
Switch on the motor.
Pay attention to product–specific characteristics. Refer
to the operating instructions of the drive motor
manufacturer.
6.2.3 Checking the delivery values
When the motor has reached its operating speed, the
inlet pressure and outlet pressure of the pump must be
checked using manometers.
The motor must not be overloaded. The current con-
sumption can be checked with an ammeter. In this con-
nection, the temperature and viscosity of the fluid must
also be checked. The readings must be checked
against the layout or acceptance test report.
The return motion from the safety valve
must not be led directly into the suction
line. Circulatory operation must be avoided. Prolonged
circulatory operation will lead to unacceptable heating
of the pumped liquid, which can result in damage to the
pump.
At no time may the permitted maximum
temperature be exceeded. Sudden tem-
perature changes are to be avoided. Within the per-
mitted operating temperature range, the temperature
gradient may not exceed 2°C/min.
To Next Page
Loading...
