Servicing
Vacuum Pump Diaphragm and Valve Replacement
Thermo Fisher Scientific
Model 42
i
Trace Level Instruction Manual
7-11
Equipment Damage
Some internal components can be damaged by small
amounts of static electricity. A properly grounded antistatic wrist strap
must be worn while handling any internal component.
▲
Use the following procedure to replace the diaphragm (
Figure 7–5
).
1.
Undo the four socket head cap screws and washers (“C”) for each head
and lift off the heads with tubing from the pump body. Keep the heads
connected if at all possible: disconnecting and then reconnecting the
PTFE tube can cause leaks.
2.
Check for smooth opening and closing of the reed valves (“Q”): a
number of sets of diaphragms can be replaced before there is a need to
replace the valves. Follow the instructions for “valve replacement” if
changing of the valves is required.
3.
Use the spanner wrench to loosen and remove the one-piece clamping
disc/screw (“E”). Remove the old diaphragms from both heads (“G”).
4.
Remove the four pan head screws with M5 washers (“J”) and remove
the housing cover (“K”) from the front of the pump body. If necessary,
carefully use a small flat-bladed screwdriver to pry-off the housing
cover.
5.
Install the two PTFE (white color) diaphragms together with one TFM
(translucent) diaphragm as shown in Figure E-1. Install with the ridges
of the diaphragm convolutions as shown in the diaphragm stack cross-
section inset.
6.
Temporarily insert two of the head screws through the diaphragms and
screw into the pump body to keep the position of the diaphragms as
the clamping disc is tightened. Any stress applied re-aligning the
diaphragm in the process of assembling the head will significantly
reduce diaphragm life
7.
Check the threads of the clamping disc to insure that they are clean and
free of debris. Apply a small amount of the breakable thread adhesive to
the clamping disc threads and install.
Diaphragm Replacement
