Replacing The Diaphragms; Removing The Sealing Diaphragm; Installing The Sealing Diaphragm; Control Diaphragms - GF DIASTAR DN65 Bedienungsanleitung

Instruction manual

8 Replacing the Diaphragms

8.1 Removing the Sealing Diaphragm

As in any diaphragm valve, the component with the most wear and tear is the diaphragm. In
addition to mechanical stress, the diaphragm is subject to wear resulting from the flow
media. We urgently recommend that the diaphragm is in-spected after 50,000 cycles. If the
flow media is muddy or contains abrasive particles, we recom-mend more frequent
inspections. The diaphragm can be inspected by dismantling the valve body. To this end,
remove the screws attaching the base to the valve body.
Elastomer diaphragms are retained by a threaded bolt and can be removed by turning it in a
counter-clockwise direction. PTFE diaphragms are equipped with a bayonet catch. To
remove, rotate the diaphragm 90° in any direction and pull out.

8.2 Installing the Sealing Diaphragm

Proceed vice versa to 8.1. Torques: see table below.
d
mm
75
90
110
160
For valves with a built-in stroke limiter, we suggest that the valve is readjusted after replacing
the diaphragm.
When reattaching the valve body, the screws must be tightened crosswise so that
the housing is compressed uniformly.

8.3 Control Diaphragms

Valves with the «fail safe to close» (FC) mode are equipped with pre-tensioned spring sets. By
removing the screws on the valve body, the spring sets are relieved to such an extent that the
actuator can be opened without any additional equipment.
Valves with the «fail safe to open» (FO) mode do not have any pre-tensioned spring sets, so
that the actuators may only be opened by the manufacturer. Detailed installation instructions
can be found in the installation manual enclosed with every spare part set.
DN
mm inch
65 2 ½
80 3
100 4
150 6
Replacing the Diaphragms
Torque
Nm
25
30
30
40
37