Emerson Fisher D & DA Bedienerhandbuch PDF herunterladen (Seite 6)

Instruction Manual

D100386X012

DandDAValves

June 2014

lubricant. Do not lubricate packing used in oxygen service. To operate the lubricator, turn the cap screw clockwise to

force the lubricant into the packing box. The lubricator/isolating valve operates t he same way except open the

isolating valve before turning the cap screw. Close the isolating valve after lubrication is completed.

Packing Maintenance

Refer to figures 3, 4, and 5 for key number locations. For spring-loaded single PTFE V-ring packing, the packing spring

(key 9) maintains a sealing force on the packing. If you find leakage around the packing follower (key 10), check to be

sure the packing follower is touching the bonnet (key 5). If the packing follower is not touching the bonnet, tighten

the packing flange nuts (key 15) until the packing follower touches the bonnet. If you cannot stop leakage in this way,

proceed to the Replacing Packing procedure.

If there is unwanted packing leakage with other than spring-loaded packing, first try to limit the leakage and seal the

stem. To limit the leakage, tighten the packing flange nuts (key 15) to at least the minimum recommended torque in

table 3. However, do not exceed the maximum recommended torque in table 3, or excessive friction might result. If

the packing (key 8) is relatively new and tight on the stem, and tightening the packing flange nuts does not stop the

leakage, a worn or nicked valve stem might prevent a seal. If the leakage comes from the outside diameter of the

packing, nicks or scratches around the packing box wall might cause the leakage. While replacing the packing per the

numbered steps b elow, inspect the valve stem and packing box wall for nicks and scratches.

Replacing Packing

Except where indicated, refer to figures3,4,and5forkeynumberlocations.

WARNING

Refer to the WARNING at the beginning of the Maintenance section in this instruction manual.

1. Isolatethecontrolvalvefromthelinepressure,releasepressure from both sides of the valve body, and drain the

process media from both sides of the valve. If using a power actuator, also shut-off all pressure lines to the power

actuator and any leak-off piping from the bonnet. Release all pressure from the actuator and relieve spring

precompression. Use lock-out procedures to be sure that the above measures stay in effect while you work on the

equipment.

Disconnect the stem connector, and then remove the actuator from the valve body by unscrewing the actuator yoke

locknut (key 14).

2. Loosen the packing flange nuts (key 15) so the packing is not tight on the valve stem. Remove any travel indicator

parts and stem locknuts from the valve stem threads.

3. Unscrew the bonnet (key 5) from the v alve body (key 1). Carefully lift off the bonnet and valve plug/stem assembly

(key 4) as a unit. Set the bonnet on a protective surface to prevent damage to the bonnet threads and gasket

surface.

4. Removethevalveplug/stemassemblyfromthebonnet.Ifyouplantore-usethevalveplug,tapeorotherwise

protect the valve plug seating surface and the stem threads to prevent damage.

5. Remove the bonnet gasket (key 7). Cover the opening in the valve body to protect the gasket surface and prevent

foreign material from getting into the body cavity.

6. Remove the packing flange nuts, packing flange, upper wiper, and follower (keys 15, 12, 21, and 10). Carefully push

out all the remaining packing box parts from the bonnet using a rounded rod or other tool that will not scratch the

packing box wall or bottom guide bushing. Clean the packing box and the metal packing box parts.

7. Inspect the valve stem threads and packing box surfaces for any sharp edges that might cut the packing. Scratches

or burrs could cause packing box leakage or damage to the new packing. If you cannot improve the surface

condition by light sanding, replace the damaged parts.

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