GF DIASTAR 025 Manuel D'utilisation page 26

Pneumatic diaphragm valve DIASTAR 025
7.3 Replacing the diaphragm
The frequency for replacing the diaphragm depends on the number of actuator cycles and the medium used. The diaphragm can be
checked by professionally disassembling the upper part.
NOTE!
The diaphragm is a consumable part!
With heavy usage the diaphragm is excessively worn and needs to be change more frequently. Worn or damaged diaphragms can
cause personal injury or property damage.
► Diaphragms and gaskets should be checked and replaced depending on the load and intensity of use.
► Only replace the diaphragm that is compatible with the valve according to the type plate.
CAUTION!
Replacing the complete diaphragm set!
If PTFE diaphragms with EPDM or FKM are used then both diaphragms must be changed.
► Make sure that both diaphragms are changed.
WARNING!
Diaphragm screwed in incorrectly!
If the diaphragm is not correctly screwed into the inner housing as specified, leaks and material damage may occur. The function of
the valve is no longer guaranteed.
► Screw the diaphragm correctly into the inner housing.
DANGER!
Do not grease the upper part of the housing!
The use of grease, especially on amorphous plastics, can cause stress cracking on the valve body. There can be consequences after
contact with hazardous medium. The functioning of the valve is no longer guaranteed.
► Do not use any grease on the threaded connection between the upper part of the housing and the valve body.
7.3.1 Removal of the sealing diaphragm
In any diaphragm valve, the diaphragm is the most stressed part. In addition to mechanical stress, the diaphragm is subject to wear
by the flow medium. It is strongly recommended to check the diaphragm after every 50 000 actuations. If the flow medium is sludgy
or contains particles with an abrasive effect, more frequent inspection is recommended. The diaphragm can be inspected by disas-
sembling the flow body.
To do this, remove the screws securing the flow body to the intermediate piece.
DN65
Elastomer diaphragms are equipped with a pressed-in threaded bolt and can be removed by turning them counterclockwise. PTFE
diaphragms are equipped with a bayonet fixing. Turn diaphragm in any direction by 90°C and pull out.
26
DN80-150
Operating Instructions