Heidolph ROTAVAC 20 - Manual (Page 25)

Documents are only to be used and distributed completely and unchanged. It is strictly the users´ responsibility to check carefully
the validity of this document with respect to his product. Manual-no.: 01-005-005-36-1
page 25 of 35 Translation of the original instructions
6.2 Replacing the diaphragm
➨ Disassemble head covers to check the diaphragm.
➨
Unscrew eight Allen screws with an Allen key size 5. Re-
move both head covers together with valve heads and
connections.
+ It is not necessary to disassemble the valve heads, the
connection fasteners, or the hose connection between the
adjacent head covers.
+ Check diaphragm for damage and replace if necessary.
➨ Lift diaphragm carefully sidewise.
+ Never use a pointed or sharp-edged tool to lift the dia-
phragm.
➨ Use the diaphragm key to grip the diaphragm support disc
below the diaphragm.
➨ Unscrew diaphragm support disc with diaphragm and dia-
phragm clamping disc.
➨ Check for washers between the diaphragm support disc
and the connecting rod. Do not mix the washers from the
different pump heads, since these are set at the factory
to ensure proper pump performance. Make sure that the
original number is reassembled at the individual pump
head.
+ Too few washers: The pump will not attain vacuum speci-
fication. Too many washers: Diaphragm clamping disc will
hit head cover, causing noisy operation and possibly caus-
ing the pump to seize up.
+ If the old diaphragm is difficult to separate from the dia-
phragm support disc, immerse assembly in naphtha or pe-
troleum ether. Do not inhale vapors!
➨ Position new diaphragm between diaphragm clamping
disc with square head screw and diaphragm support disc.
+ Note: Position diaphragm with pale side towards dia-
phragm clamping disc (facing pump chamber).
+ Make sure that the square head screw of the diaphragm
clamping disc is correctly seated in the guide hole of the
diaphragm support disc.
➨ Lift the diaphragm at the side. Place the diaphragm care-
fully together with diaphragm clamping disc and diaphragm
support disc in the diaphragm key.
+ Avoid damage of the diaphragm: Do not excessively bend
or crease the diaphragm.
+ Assemble the original number of washers between dia-
phragm support disc and connecting rod.
➨ Screw diaphragm clamping disc, diaphragm, diaphragm
support disc, and washers to connecting rod.
➨ Optimum torque for the diaphragm support disc: 6 Nm, it
is recommended to use a torque wrench. Attach Allen key
to diaphragm key (hexagonal bolt 6 mm wide).
Note: Never use the diaphragm key with any additional
tools like tongs or Allen keys without appropriate torque
limitation.