M&H 4500, Руководство пользователя

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5. If the lever/crosshead interface is damaged, again, there may be some limited movement of the
operator before the binding occurs.
6. Check for binding between the thrust cap to the input shaft by loosening the thrust cap (thread off to
right).
Section 5.4.4 – Internal to the Valve Obstruction
1.
Minimum Mating Inside Diameter – The Inside Diameter of the adjoining pipe may interfere with
vane opening. This is generally a consideration only when using thick wall (non-metal) piping
systems with mechanical joint end valves. Consult the ‘Minimum Mating ID Chart’ for specific
dimensions needed for vane clearance.
2. If the Pipe ID is too small, the vane will have normal movement from the closed position for
approximately 1/3 the number of turns of the operator. Once the vane contacts the pipe wall,
movement will stop. The valve will “free up” as the vane is moved back to the closed position.
NOTE: Impact with the pipe wall will normally cut the rubber vane ring and the valve will now leak
in the closed position.
3. If the Minimum Mating ID Chart and operating conditions point to vane interference as the problem,
the valve must be removed from the line and appropriate piping modifications completed. Inspect the
seat for damage prior to reinstalling valve.
4. If the valve has good movement from the Open position but binds as it approaches the Closed
Position, it is likely that there is an obstruction in the line preventing the valve from fully closing.
5. The only way to verify an internal obstruction to gain access to the inside of the piping system to
BFV vane.
6. If there is an internal obstruction, the vane must be accessed to physically remove the obstruction.
Section 5.5 – Vane Level Adjustment
M&H BFVs, 3” thru 42”, are generally equipped with a mechanical traveling nut operator. The operator
lever adjustment is set during the production/testing process and the valve pressure tested in both
directions for proper sealing at full closure. As a result, field adjustment is rarely required.
Section 5.5.1 – Vane Level Adjustment Procedure for 3” thru 12” BFVs
Call your customer service representative for the current procedure.
Section 5.5.2 – Vane Level Adjustment Procedure for 14” thru 42” BFVs
An external locking bolt adjustment feature was added to M&H BFVs in 1998.
1.
Loosen the Lock Nut retaining the Hex Head Bolt. (For open left valves, the closure adjustment is
located near the op nut or handwheel)
2.
Turn the Hex Head Bolt so that it moves outward from the Operator Housing. Do not unthread the Hex
Head Bolt to where it comes out of the housing. Normally, 1 to 3 turns is sufficient.
3.
Using the Op Nut or Handwheel, level the valve a needed. Assuming the valve itself is level, a small
Carpenter’s level can be placed on the vane to set the level.