6
5.
Remove the packing nut from the valve bonnet.
6.
Remove all old packing, adapters and spring from the valve bonnet. One technique is to admit a small
amount of pressure into the valve body until the packing is forced out of the stuffing box. Shield the bonnet
as some spray may occur as the packing emerges.
DO NOT SCRATCH THE BORE OF THE STUFFING BOX WITH SHARP TOOLS.
7.
Clean all surfaces of the stuffing box and stem. Remove all accumulations of mineral deposits or other debris
before re-building. A 0.4375 diameter reamer is ideal to remove deposits from bonnet, if the bonnet is
removed from the body. A 0.45 diameter brass brush is often also very effective. Do not use abrasives on
the valve stem nor in the stuffing box since scratches will cause leakage. The valve stem originally was
polished to a 12 micro-inch finish and this polish should be preserved. If the stem is corroded, worn, or
marred it must be replaced. See section on “Reversing Valve Action”.
8.
Blow all debris from the stuffing box and the replacement packing before re-building.
PACKING MUST BE CLEAN & FREE OF FOREIGN MATERIAL.
9.
Install new packing as follows:
a) Spring
b) Male adapter with flat side in first against spring.
c) V rings with lips in first.
“V” rings must be carefully installed over the stem threads and into the
stuffing box bore to avoid snagging of the lips on the threads of bore
entrance. The clean edge on these lips is imperative for proper sealing.
d) Female adapter with cavity in against “V” rings and flat side out.
e) Packing nut.
10.
Tighten packing nut all the way down onto the bonnet to push all rings down into
the stuffing box and to obtain proper spring load on the assembled rings.
TIGHTEN FINGER TIGHT ONLY.
11.
Replace the stem locknuts and re-position and lock in place as previously measured in step 2. If this
dimension is not available, see section on “Replacing Valve Body Assembly” and use the dimension as
described in the table
12.
Re-assemble Valve Body to Actuator as shown in section titled “Replacing Valve Body Assembly”.
CHECKING THE REGULATOR FOR PROPER ACTION
The thermal actuator will become inoperative if any leak occurs in the thermal system, allowing the pressure to
escape from the system. This will in turn cause the bellows to retract upward causing the regulator to control as if
the measured process had turned very cold. A heating valve will fully open and a cooling valve will fully close.
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CAUTION:
NEVER SEPARATE YOKE FROM CAP
Removal of the four screws can cause injury due to the
rapid expansion of pressurized bellows and captive spring tension
.
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Inspecting the Actuator
On the Model W94 the dial thermometer is an integral part of the thermal system. To check the thermal system for
action simply read the dial thermometer. If, with the valve still attached, the dial thermometer is indicating a proper
temperature the actuator is good. If the dial thermometer is indicating a very low temperature, possibly completely
off of and below the scale, then the thermal system is most likely dead and needs to be replaced.
