Uni Directional
Knife Gate Valve

Body :

The body is lugged type Wafer Design single piece of Cast steel / Stainless steel (Investment Cast upto 200 mm). It is designed to withstand pipeline stresses while in service. The body is available in variety of materials that provide corrosion and abrasion resistance. Guide Lugs are provided on the body to hold the gate securely against the raised face seat to assure positive shutoff. The body has drilled and tapped lugs on the outer rim drilled & tapped in accordance with different flange standards such as ANSI 150, ANSI 300, BS10 TD, BS10 TE, PN10, IS 1538 etc.

Gate :

Precision machined thick Stainless steel gate provides good sealing and smooth operation. The beveled knifelike edge pushes aside or cuts through solids in the flow stream. The gates are available in different materials to suit various applications.

Stem :

The Stem is of stainless steel with double start ACME threads, designed to reduce operating torque and for easier, faster operation & longer life.

Gland :

The Investment Cast Gland is of Cast steel / Stainless steel with precisely controlled dimensions to ensure minimum gap between Body and Gate to have better performance.

Gland Packing :

The Gland Packing is Multi-layered square PTFE Impregnated packing for complete leak tightness and to offer seal to the atmosphere. High temperature packing is available upto 1400 deg C and other options are available for different applications.

Yoke :

The heavy duty fabricated Yoke is designed to provide support, strength & withstand stresses.

Yoke Sleeve :

The Bronze Yoke Sleeve provides corrosion resistance and assures easy operation. A grease fitting provides lubrication to the sleeve and stem.

Seat Options :

The valves are available in metal seated and resilient seated round port designs.

Actuator :

The standard valves are provided with hand-wheel. The other actuators such as Chain Wheel, Lever, Bevel Gear, Pneumatic Cylinder & Electric Motor are available on request.


Size range

2" (50 mm) to 104" (2600 mm)

Handwheel

The standard valves come with the Handwheel arrangement (Rising Stem Type).

Handwheel with Locking Arrangement

Valve with non rising stem hand wheel and locking arrangement.

Chain Wheel

A Chain Wheel is provided in place of hand-wheel in applications where the valve is located at an elevation.


Lever

Lever actuators are suitable for smaller valves (below 300 mm). They are used where actuation forces are small and rapid valve operation is required or where space prevents use of standard hand-wheel or worm gear.

Pneumatic

Pneumatic actuators are provided for on-off application service. The gate is operated by a double acting pneumatic cylinder. Accessories like solenoid valves, limit switches etc. are provided as per customer's requirement / specification.

Electric

Electric Motor Actuators are provided for on-off or throttling applications. They are provided with manual over-ride arrangement to take care in case of power failure. The service conditions, type of application, speed of operation, electric characteristics are the factors governing the actuator selection.


Pneumatic with Manual Override

Bevel Gear

This arrangement is provided in application where space limitations prohibit use of standard hand-wheel. A mechanical advantage makes operation of large size valves easier and faster.


Optional Accessories

Deflector Cone

Deflector cone is provided on the inlet of the valve for critical service application where abrasion is high. The Deflector cone is normally of Ni-hard material and protects the valve body. It is installed between the valve and the pipe flanges and diverts the abrasive material flow to the valve.

The typical application involve Bin bottom, for dry solids, mining slurries, fly-ash, bag-filter, cyclone bottom.


Purge Connection

The purge connections are used to flush the seat area and minimize the chance of material getting clogged on the seat, thus helping smooth operation of the gate. Purge connections are located at 5 and 7 'O' clock positions on 6" and smaller size valves and at 3,5,7 and 9 'O' clock positions on 8" and larger size valves. The purge connection can also be provided in the chest area and is normally furnished with pipe plugs and are used only for flushing if required.


Pneumatic with Fail Safe System & Manual override


Surface Treatment

The valve components can be offered with protective coatings / surface treatment typically hard facing of seat areas (Stelliting / Nitriding of body, seat and gate edge) is done, depending on the application to increase the life expectancy.

Other Accessories

  • Locking Device
  • Extended Stem
  • Proximity Switches
  • Solenoid Valves
  • Limit Switches
  • Air Filter (Regulator)
  • Chain for chain-wheel actuator
  • Mating flanges & hardware

V-Orifice

The metal seated V-port design version of Knife Gate Valve is available for throttling application. The constant V-orifice is maintained to ensure maximum control accuracy.


Hopper Isolation Knife Gate Valve

This valve is specially designed for use as isolation valve for silos handling powders. The body design includes a large relieved area on the downstream side that can accommodate some material accumulation without affecting the closing operation of the valve. Tthese valves are typically mounted with seat facing downward under silo, the body is provided with large cast guides to support the material load on the gate. This design uses a thinner gate than standard knife gate valves as same is sufficient for the typical gravity flow situations where such valves are used. The valve is designed to be dust tight.

Body with relieved outlet area
and multiple cast gate supports

Flat edge beveled gate

Typical Applications
  • Gravity flow silo isolation
Specifications
  • Type - Uni-directional knife gate valve
  • Size range - 100,150,200,250, 300, 350, & 400mm
  • Pressure rating CWP-5 bar - (75 psi)
  • Endstyle - Flanged
  • Face-to face - Proprietary
  • Drilling - Proprietary
  • Body - Cast iron
  • Seat - Integral metal seat
  • Gate - 304stainless steel
  • Stem - SS 410, SS 304, SS 316
  • Superstructure - Epoxy coated steel channel fabricated
  • Actuator options - Hand wheel, chain wheel, pneumatic actuator

Coal Mill Knife Gate Valve

Typically these valves are used to isolate the coal mill from the boiler furnace and are normally kept open during service. They are closed to isolate the mill from the hot flames and gases in the boiler furnace during emergency shut downs and for routine maintenance. During normal operation, when the valve is open, mixture of air and fine pulverized fuel (eg., coal) at very high velocity passes through the valve- This is a very abrasive media and calls for a valve that offers minimum flow restriction and has internal parts with high erosion resistance.

A unidirectional flanged knife gate valve specially designed to meet these exacting service requirements. It features a body construction with the bore matching the pipeline bore which keeps the pressure drop in the valve to the minimum. This means there is no raised seat in the flow path as in the case of standard knife gate valves. The internal bore of the valve is usually hardfaced to provide high resistance to erosive wear.

This valve is designed to comply with the requirements of NFPA-85 (2001) standard which governs equipment used in coaf mills and associated piping.
These valves are normally supplied with a powered actuator, usually pneumatic or electric. Other actuation options are also available where required.

Design Highlights

Conformance to NFPA-8503 Designed - to comply with requirements of NFPA-S5 (2001)
Full bore Minimum resistance to flow with bore identical to pipe bore or more.
Hard faced valve bore - For resistance to highly abrasive and continuous material flow the valve bore is provided with suitable hardfacing, Seat face steiliting is aiso available as an option.
Stem protection bellows - For reliable operation in dusty environment.

Specifications

  • Type - Uni-directional knife gate valve
  • Size range - 100mm to 650rnm (higher sizes on application)
  • Design - Full port design conforming to NFPA-85 (2001)
  • Rating - Designed to comply with the requirements of NFPA-85 (2001)
  • Endstyle - Wafer- flanged standard; lugged versions also available
  • Drilling - ANSI 1501b,& others
  • Body - Carbon steel, stainless steel
  • Gate - 304/316 Stainless steel
  • Packing - PTFE impregnated syntex fibre as standard; other packing materials and wiper packing options available.
  • Purges - Chest purges are provided as optional.
  • Actuator - Pneumatic double-acting cylinder with nitrile/viton energized PTFE piston seal or electric actuator
    Manual - valves with rising stem handwheel or geared handwheel