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Description
The plug valve eliminates taper lock, for years of dependable service with little or no maintenance, even in hostile environments.
“Positive Bias” Balance Plug Design
The COMPENSATOR plug valve design is based on a load compensating, mechanically balanced tapered plug, which cannot bind or lock.
Maintenance is virtually eliminated; lower operating torque is achieved, and size and weight are reduced by 20% to 25%.
The COMPENSATOR provides these major benefits, while retaining the positives attributes of automatic shut-off, fire safety, and resistance to corrosion and erosion not found in conventional tapered plug valves.
How it Works
Unlike other lubricated plug valve designs, WALWORTH’s COMPENSATOR plug valve does not rely on sealant or line pressure to keep the plug from wedging or binding in the valve body.
Instead, the COMPENSATOR utilizes SS-304 long life spring-type helicoidal and an adjusting screw to mechanically balance the plug and compensate for line pressure.
The function of the sealant, therefore, is to provide a backup to the tight seal between the plug and body. The sealant chamber is isolated from the line media.
A sealant fitting is provided to permit injection of sealant into the isolated chamber to assure a bubble tight seal and to lubricate internal parts.
Positive Downward Bias Pressure Balance
There is a passageway with a ball check between the flow port of the plug and the lower chamber.
When a pressure rise occurs in the flow port area, the ball check is held shut, forcing pressure equalization to take place through the annular clearance gap at the top and bottom of the lubricated plug.
Since the net differential plug area is greater at the bottom, the result is a net downward force acting on the plug.
In the event of a sudden drop in flow port pressure, the positive bias downward is maintained because the upper sealant chamber is forced to equalize through the annular gap, while the lower cavity equalizes through both the gap and the ball check valve.
Thus, the lower chamber reaches equilibrium with the flow port well before the upper chamber, causing the plug to stay against the ball at its base.
Features- Open/Close Indicator - quarter turn stop collar also functions as an indicator of the plug`s position
- Stem Sealing System - the stem is protected two ways. The weather seal protects it from external attack. High temperature soft packing protects the stem against internal leakage
- Balancing Spring - the mechanical spring type grade 304 Stainless Steel is under compression and holds the plug in an equalized pressure position, thus eliminating the possibility of plug taper lock
- Isolated Sealant Chamber - the sealant`s function is to provide a backup to the positively biased surface between the plug and the body
- Plug - the mechanically balanced plug has a permanently bonded PERFLO coating for a very low coefficient of friction. Operating torque remains low over the 4,000 cycle test life of the valve
- Plug Adjustment - the steel plug is mechanically loaded into the body to put tension on the balance spring and is then adjusted for optimum balance and performance. The adjustment screw is covered to prevent tampering and possible misadjustment
- End to End Dimension as per ASME B16.10 to meet Short Pattern Length
- Flanged Dimensions conform to ANSI/ASME B16.5, B16.34
- Butt-weld Dimensions conform to ANSI/ASME B16.25
- Design as per API 6D
- Fire Test as per API 6FA
