VACUUBRAND BVC 21 - Manual (Page 20)

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.: 999054 / 15/12/2009
page 20 of 27
Assembling pump head:
➨ By turning eccentric bushing (front of connecting rod), bring
connecting rod into a position in which diaphragm is in con-
tact with housing and centred with respect to bore.
Replacing the diaphragm:
☞ Check diaphragm for damage and replace if necessary.
➨ To do so use Phillips screw driver to remove four counter-
sunk head screws and lift off housing plate with rating plate.
☞ Use petroleum ether or industrial solvent to remove depos-
its if necessary. Do not inhale.
➨ Use a face wrench to remove diaphragm support disc.
➨ Check for washers under clamping disc. Make sure that the
original number is reassembled.
☞ Smaller number of washers: The pump will not attain ulti-
mate vacuum. More washers: Clamping disc will hit head
cover; noise or even blockade of the pump.
➨ Use face wrench with torque indicator (recommended: face
wrench with torque indicator from VACUUBRAND, Cat.-
No.: 63 75 80) to assemble diaphragm clamping disc, dia-
phragm and diaphragm support disc (and eventually wash-
ers) to the connecting rod.
☞ Make sure that the square head screw of the diaphragm
clamping disc is correctly seated in the guide hole of the
diaphragm support disc.
Optimum torque for the diaphragm support disc: 6 Nm.
☞ The optimum torque is achieved if the pointer in the handle
of the VACUUBRAND face wrench shows to the longer mark-
ing line.
➨ Position new diaphragm between diaphragm clamping disc
with square head screw and diaphragm support disc.
☞ Make sure that the square head screw of the diaphragm
clamping disc is correctly seated in the guide hole of the
diaphragm support disc.
☞ Attention: Position diaphragm with pale side to diaphragm
clamping disc (to pump chamber).