Hoefer VP200 - Manual (Page 28)

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Checking the ultimate vacuum
After any intervention at the equipment (e.g., repair/
maintenance) the ultimate vacuum of the pump has
to be checked. Only if the pump achieves its specified
ultimate vacuum, the pump’s leak rate is low enough
to ensure that no explosive atmospheres will occur in
the interior of the equipment.
If the pump does not achieve the ultimate
vacuum:
• Whenever the diaphragms and valves have been
replaced, a break-in period of several hours is
required before the pump achieves its ultimate
vacuum.
• In case of an unusual noise, switch off pump
immediately and check clamping disc positions.
If the specified ultimate vacuum is not achieved, and
if this does not change after the break-in period:
Check hose connectors at pump heads for leaks. If
necessary recheck valve seats and pump chambers.
Measure inlet port pressure
Measure the inlet port pressure with a vacuum gauge
(Fig 3). A vacuum of less than 120 mbar should be
indicated. Any reading in excess of 120 mbar requires
disassembly to check that the valves and diaphragm
are properly seated and placed. The diaphragm must
be concentric within the bore.
Note: New parts require a run-in
period of several hours before
achieving the ultimate vacuum.
If the pump heads tested below
120 mbar and the ultimate
vacuum is not achieved, check
all hose connectors for leaks.
Fig 3. Measure inlet port pressure.