Hoefer VP200 - Manual (Page 17)

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5. Troubleshooting
Problem Solution
Pump fails to start or Check that the power cord is completely plugged into a
suddenly stops working power outlet.
When the pump motor overheats, a thermal cutoff switch
stops the motor. If this occurs, check that the mains power
switch is in the off position, wait for the pump to cool, and
correct the cause for overheating (e.g. constricted tubing).
To restart the motor, switch the mains power switch to
on. In case of supply voltage below 100 V, the lock of the
cutout might be restricted and the pump might restart on
its own after sufficient cooling down.
Clear any blockage at the outlet end of the system.
If the pump seizes, call your local Hoefer, Inc.
sales office.
Pump does not achieve Close the gas ballast valve (arrow pointing up or down
rated pressure or normal instead of right). Check the vacuum strength with a
pumping speed vacuum gauge installed at the pump inlet port. If
the pressure is outside the rating, check all lines and
connections for leaks.
Vacuum tubing should be as short as possible.
Use the recommended 8 (or up to 10) mm i.d. heavy
walled vacuum tubing. Thinner walled or smaller i.d.
tubing may not withstand the vacuum pressure without
collapsing.
Clear excess condensate from the system by running the
pump at atmospheric pressure (not connected to
a load) for several minutes.
Replace worn diaphragms or valves (see “Servicing
diaphragms and valves” page 12).
Pump too noisy Check if the diaphragm clamping disc is loose (see
“Servicing diaphragms and valves” page 12).
If the pump is operated under conditions of high inlet
pressure, the resulting sound of pumped gas can be
dampened considerably by connecting a hose to the pump
outlet nozzle and conducting the hose to a more remote
area such as under a fume hood.