Cla-val 50B-5KG User Manual download pdf (Page 10)

Lime Deposits

One of the easiest ways to remove lime deposits from the valve

stem or other metal parts is to dip them in a 5-percent muriatic

acid solution just long enough for the deposit to dissolve. This

will remove most of the common types of deposits. CAUTlON:

USE EXTREME CARE WHEN HANDLING ACID. Rinse parts in

water before handling. If the deposit is not removed by acid, then

a fine grit (400) wet or dry sandpaper can be used with water.

Reassembly

1. Reassembly is the reverse of the disassembly procedure. If a

new disc has been installed, it may require a different number of

spacer washers to obtain the right amount of “grip” on the disc.

When the diaphragm assembly has been tightened to a point

where the diaphragm cannot be twisted, the disc should be com-

pressed very slightly by the disc guide. Excessive compression

should be avoided. Use just enough spacer washers to hold the

disc firmly without noticeable compression.

2. MAKE SURE THE STEM NUT IS VERY TIGHT. Attach a good

fitting wrench to the nut and give it a sharp “rap” rather than a

steady pull. Usually several blows are sufficient to tighten the

stem nut for final tightening. Failure to do so could allow the

diaphragm to pull loose and tear when subjected to pressure.

Test Procedure After Valve Assembly

There are a few simple tests which can be made in the field to

make sure the Hytrol Valve has been assembled properly. Do

these before installing pilot system and returning valve to

service. These are similar to the three troubleshooting tests.

1. Check the diaphragm assembly for freedom of movement

after all pressure is removed from the valve. SEE CAUTlON.

Insert fabricated tool into threaded hole in top of valve stem, and

lift the diaphragm assembly manually. Note any roughness,

sticking or grabbing. The diaphragm assembly should move

smoothly throughout entire valve stroke. The tool is fabricated

from rod that is threaded on one end to fit valve stem (See chart

in Step 4 of “Disassembly” section.) and has a “T” Bar handle of

some kind on the other end for easy gripping.

Place marks on this diaphragm assembly lifting tool when the

valve is closed and when manually positioned open. The dis-

tance between the two marks should be approximately the stem

travel shown in stem travel chart. (See “Freedom of Movement

Check” section.) If the stroke is different than that shown, there

is a good reason to believe something is mechanically restricting

the stroke of the valve. The cover must be removed, the obstruc-

tion located and removed. (See “Maintenance” Section for

procedure.)

Inspection of Parts

After the valve has been disassembled, each part should be

examined carefully for signs of wear, corrosion, or any other

abnormal condition. Usually, it is a good idea to replace the rub-

ber parts (diaphragm and disc) unless they are free of signs of

wear. These are available in a repair kit. Any other parts which

appear doubtful should be replaced. WHEN ORDERlNG

PARTS, BE SURE TO GIVE COMPLETE NAMEPLATE DATA,

ITEM NUMBER AND DESCRlPTlON.

NOTE: If a new disc isn’t available, the existing disc can be

turned over, exposing the unused surface for contact with the

seat. The disc should be replaced as soon as practical.

3. Carefully install the diaphragm assembly by lowering the stem

through the seat bearing. Take care not to damage the stem or

bearing. Line up the diaphragm holes with the stud or bolt holes

on the body. on larger valves with studs, it may be necessary to

hold the diaphragm assembly up part way while putting the

diaphragm over the studs.

4. Put spring in place and replace cover. Make sure diaphragm

is Iying smooth under the cover.

5. Tighten cover nuts firmly using a cross-over pattern until all

nuts are tight.

6. Test Hytrol Valve before re-installing pilot valve system.

Due to the weight of the diaphragm assembly this procedure is

not possible on valves 8” and larger. on these valves, the same

determination can be made by carefully introducing a low

pressure-less than five psi) into the valve body with the cover

vented. SEE CAUTION. Looking in cover center hole see the

diaphragm assembly lift easily without hesitation, and then

settle back easily when the pressure is removed.

2. To check the valve for drip-tight closure, a line should be

connected from the inlet to the cover, and pressure applied at the

inlet of the valve. If properly assembled, the valve should hold

tight with as low as ten PSI at the inlet. See “Tight Sealing

Check” section.)

3. With the line connected from the inlet to the cover, apply full

working pressure to the inlet. Check all around the cover for any

leaks. Re-tighten cover nuts if necessary to stop leaks past the

diaphragm.

4. Remove pressure, then re-install the pilot system and tubing

exactly as it was prior to removal. Bleed air from all high

points.

5. Follow steps under “Start-Up and Adjustment” Section in

Technical Manual for returning complete valve back to service

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Cla-val 50B-5KG User Manual Page 10

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