DIAPHRAGM VALVES


 

DIAPHRAGM VALVES

Diaphragm Valves are designed and manufactured according to BS 5156. They are extensively used in water treatment plants, fertilizer & petrochemical industries, chemical process units, refineries and power plants. They are suitable for positive pressure and high vacuum applications. Due to wide range of material options it is suitable to handle almost all applications within its pressure-temperature limitations.

Total wet area and working parts are isolated from the working media by suitable lining with various qualities of Rubber, PTFE/PFE etc. ensures handling of highly corrosive fluids in efficient and safer manner

The diaphragm valve is different from all the valves previously described because the bonnet and the stem are always completely isolated from the product. A diaphragm valve is almost equivalent to a bellows sealed linear valve. The diaphragm ful-fils two functions. Firstly it separates the inlet from the outlet when the valve is closed and secondly it separates the operating mechanism from the product. The diaphragm forms a part of the pressure containment

The diaphragm is clamped between the body and the bonnet. Bolted bonnets are standard. No packing box is required. The bonnet has an inside rising screw, Which can have a sealed lubrication reservoir. A shield on the hand wheel is sealed by a lip seal to prevent ingress of moisture or dust into the thread area. The Operating mechanism is sealed both ways for long life. Valve maintenance is easy once the line is depressurized and all parts can be removed from under he bonnet

Valve shut-off capabilities are excellent because of the elastomer diaphragm. Solids handling is quite good, with 15% maximum recommended concentration. Diaphragm valves are a sensible choice for hazardous fluids because there is no packing box to worry about. Routine diaphragm maintenance will ensure almost total containment and diaphragm life can be optimized by the fitting of limit stops to the actuator. Over-tightening is eliminated thus reducing stresses in the elastomer. The Precise level of containment is dependent upon the fluid. Elastomers are permeable; Although permeation through a diaphragm should be considerably less than the leakage through any packing box. Diaphragm valves are used on hydrogen services, and containment must be good.

The diaphragm is the main limiting restriction on operational parameters. To widen the range as much as possible a broad selection of materials is used. Materials are also combined to improve flexibility and chemical resistance. The most popular materials are listed

Maintenance of these Valves are made very simple. By dismantling the Bonnet from the Body, the entire Trim Assembly can be taken out for maintenance and the Body remains in the Pipeline. Thus the design permits online maintenance and saves time and energy. It has linear flow characteristics, which makes it well suited to throttling or modulating duties. On/off and control automation is provided with Pneumatic Actuators or Cylinders

 

Diaphragm materials Min.Temperature °C Max.Temperature °C
Gum rubber -50 to -29 70 to100
EPDM -34 149
PTFE(1) -34 176
Butyl rubber -29 to -18 107 to 120
Neoprene -20 90
Nitrile rubber -12 82
Hypalon -10 100
Vitan 5 150
PTFE + EP rubber -30 150

SAFETY / PRESSURE RELIEF VALVES  THERMAL RELIEF VALVE    ATMOSPHERIC RELIEF VALVE   PRESSURE REDUCING VALVES / STATION   PRESSURE CUM VACUUM RELIEF VALVES  BREATHER VALVES   EXCESS FLOW CHECK VALVES   EXCESS FLOW  SHUT  OFF VALVES   UNDERGROUND SAFETY VALVES FOR WATER TANK /  WATER FLOW CANAL AS PER BS – 4558 : 1983    NON – RETURN VALVES   BALL VALVES    NEEDLE  VALVES / MANIFOLDS/ THROTTLING VALVES     FLUSH BOTTOM VALVES