Hoefer VP200 User Manual

Page 22

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p14

Replacing the diaphragm

Disassemble head covers (J) to check the
diaphragm (F).

Unscrew four (pump with one/two heads) Allen
screws (H) with a 5 mm wide Allen key. Remove both
head covers (J) together with valve heads (O) and
connections.

Check diaphragm (F) for damage and replace if
necessary.

Lift diaphragm carefully sidewise. Never use a pointed
or sharp-edged tool to lift the diaphragm.

Use the diaphragm key to grip the diaphragm support
disc (E) below the diaphragm.

Unscrew diaphragm support disc (E) with diaphragm
(F) and diaphragm clamping disc (G).

Check for washers (D) between the diaphragm support
disc (E) and the connecting rod (B). Do not mix the
washers from the different pump heads, since these
are set at the factory to ensure proper pump perfor-
mance. Make sure that the original number is reas-
sembled at the individual pump head.
Too few washers: The pump will not attain vacuum
specification.
Too many washers: Diaphragm clamping disc will
hit head cover, causing noisy operation and possibly
causing the pump to seize up.
If the old diaphragm is difficult to separate from the
diaphragm support disc, immerse assembly in naph-
tha or petroleum ether. Do not inhale vapors!

Step 1

Step 3

H J