5.
MAINTENANCE, ADJUSTMENTS AND CALIBRATION
Page 187
© 1998-2008 DH Instruments, a Fluke Company
5.3.2.2
DISASSEMBLY AND REASSEMBLY OF GAS
OPERATED, LIQUID LUBRICATED
PISTON-CYLINDER MODULES (PC-7200)
The PG7000 piston-cylinder module design affords maximum protection to
the piston-cylinder element assuring that it is protected during routine piston-
cylinder handling. Cleaning the piston-cylinder requires disassembly of the module
and exposure of the piston-cylinder to possible damage. These risks include damage
to the critical working surfaces for all piston-cylinder sizes and chipping or breaking,
especially for small diameter piston-cylinders. Only qualified personnel should
undertake piston-cylinder disassembly, cleaning and reassembly. The instructions
and recommendations contained in this manual should be followed carefully
throughout the operation.
NEVER touch the lapped surfaces (polished appearance) of the piston or
cylinder with your bare hands. Body oils and acids can permanently
etch the surfaces.
In normal use, always maintain PC-7200 gas operated, liquid lubricated piston-
cylinder modules vertical with the O-ring assembly down. Tilting or inverting the
assembly can cause the liquid in the modules reservoir to run out. Inverting the
assembly can allow liquid to run up into the piston head into the adjustment mass
and cap. Liquid contamination of the piston head and cap changes the mass of the
piston assembly and could lead to out of tolerance pressure definitions at low mass
loads. If liquid contaminates the adjustment mass and cap, disassemble the module
and clean it (see Section 5.3).