WIKA CPB3800 - Handbuch (Seite 23)

23 WIKA operating instructions model CPB3800
14062232.03 12/2013 GB/D
GB
4. Design and function
Masses are loaded directly onto the piston head for low pressure calibration points. A
coloured band indicates when the piston is floating.
For higher pressure points, an overhang is fitted directly to the piston head, and weights
located at the bottom of the overhang or located on top of it. A machined groove on the
main piston body indicates when the piston is floating.
4.5 Function
Operation of the pressure balance is controlled by the two valves A and B on the top of
the reservoir/high pressure cylinder block. When initially priming the system valves A
and B are opened to fill the system with oil from the reservoir. Valve B is then closed with
valve A left open and the spindle pump operated to provide the lower test pressures.
To provide the higher pressures valve A is closed to seal off the test circuit from the low
pressure part of the spindle pump and valve B is opened to allow the liquid in the low
pressure part of the spindle pump to return to the reservoir as the pump is operated.
This ensures that the pump can be operated without having to put large forces on the
spindle pump handwheel. To release the test pressure the spindle pump is wound out
and valve A is opened.
Reservoir
Valve A
Hand pump
Valve B