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Get Acrobat Reader You will need Acrobat Reader to view pdf Storage, Installation, Testing, Operation and Maintenance Guidelines for Diaphragm Valves

Storage and handling

Because metal housings and plastic liners can become brittle at low temperatures, use care when handling valves at temperatures below freezing.

Also, do not remove wooden end protectors provided with each valve until you're ready to install the valve. After you remove them, inspect the valve and liner for possible physical damage.

Installation
  • Gaskets are not required between flanges of lined diaphragm valves and lined pipe because the plastic faces of each provide the sealing.
  • Retorque bonnet bolts immediately before installation. Torquing should only be done on the system in the ambient, cooled state, never while the process is at elevated temperature. Otherwise, excessive force could be applied to the plastic faces.
    Bonnet hex nut torque valves (ft-lbs)
    Valve size,
    inches
    Elastomeric
    diaphragms
    PTFE
    diaphragms
    1 15 30
    1 1/2 15 30
    2 20 40
    2 1/2 30 60
    3 55 120
    4 40 60
    6 65 110
    8 80 125
  • Follow flange Bolt Torquing guidelines.
  • Do not overtighten. This could damage the sealing faces.
  • For connecting valves to unlined flanged faces, see pipe connect details.
Testing

Test the installed valve to the pressure not exceeding the working pressures. CAUTION: Do not use steam to pressurize the valve for testing. Reason: The temperature of steam is difficult to control and can easily exceed the temperature limits of the liner.

Operation

After the first system thermal cycle and subsequent shutdown, check and retorque the flange bolts to the valves shown here.

After the system is put into service at the expected operating temperature, check each valve for leaks. If a valve is leaking from the bonnet/body connection, tighten the bolting 1/6 turn in a criss-cross pattern. Repeat as necessary until the leak stops. Make sure that improper alignment or support is not the cause of the leak.

During nominal operation, a visual inspection for leaks should be made on a regular basis by the operator.

Maintenance

Preventive maintenance -
  • To maximize the life of the diaphragm, do not tighten the handwheel beyond one-half turn after initial shut-off.
  • Grease the handwheel spindle every four months with a quality, high-temperature grease. Be careful not to over-grease.
  • The travel stop is factory set, but can be adjusted as follows
    • Loosen the set screw
    • Close valve at operating pressure until it seals and then turn the handwheel clockwise an additional one-quarter turn.
    • Position the travel stop against the valve handle and tighten the set screw.
  • Do not steam-clean polypropylene, or PVDF-lined valves. You can use steam to clean PFA-lined valves, but be sure to keep the steam temperature below the maximum temperature limit of the plastic and the diaphragm.
Corrective maintenance -

How to Replace Diaphragms

If the valve has to be replaced, follow these steps:
  • Make certain the line is isolated, pressure relieved, drained, and appropriate safety equipment (chemical goggles, face shield, protective clothing, etc.) is worn before attempting to remove the valve.
  • Remove the valve from the line. If the valve has been used in hazardous chemical service, make sure it is thoroughly cleaned and/or neutralized before repairing or disposing of it.
  • Install the new valve according to procedures explained in the "Installation" section of this page.


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