Wilkerson B28A - Manual (Page 2)

shoulder above the panel nut threads. Also, internally the body has raised
characters “28A.” Once the diaphragm is removed, this can be seen. Parts
from B28 and B28A units are NOT interchangeable. You can NOT use B28
unit parts in B28A units; nor can you use B28A parts in B28 units. When
repairing the B28 and the B28A units, make your identification by looking
for the identifying “28A” mark on the bonnet, and then select the repair
part numbers accordingly from the parts listed on the back of this sheet. If
you are unsure of which regulator you have, contact your local Wilkerson
distributor or call Wilkerson.
1. Filter element replacement:
a. DePReSSURIze both upstream and downstream pressure.
b. Remove bowl / bowl guard assembly by pushing up on bowl assembly
and turning counterclockwise (viewed from below). Clean inside of
bowl using a clean, dry cloth. Inspect plastic bowl for damage and
replace if necessary.
c. Remove filter element by turning retainer counterclockwise.
d. Remove old element and discard. On series B28, care must be taken at
this step not to lose or misplace the valve spring and valve assembly,
as these components may be removed during this procedure.
e. Install a new filter element and reassemble in reverse order. See
table side for torque values.
2. Valve assembly:
a. Depressurize both upstream and downstream pressure.
b. Remove bowl / bowl guard assembly and element retainer assembly
as outlined in maintenance Step #1. Additionally, the 28A deflector
needs to be removed. Care must be taken at this step not to lose or
misplace the valve spring and valve assembly, as these components
may be removed during this procedure.
c. Remove the valve spring and valve assembly, if not already done.
d. Inspect all seals and components for damage and replace as
required. Clean seals and components with mild detergent and
water (No Solvents!). Use a clean, dry cloth to wipe any
contamination from the valve seat inside the body.
e. Lubricate valve stem and lower valve O-ring seal with a light coat of
lubricant.
f. Reassemble in reverse order. See table on reverse side for torque
values.
3. Main Spring and Diaphragm:
a. Depressurize unit, both upstream and downstream.
b. Turn adjusting knob counterclockwise to remove all spring force,
then remove bonnet by turning counterclockwise.
c. Remove adjusting screw assembly, main spring, slip ring and
diaphragm assembly.
d. Inspect diaphragm and the relief seat, on relieving models, for
damage or contamination. Replace diaphragm assembly if
necessary. Clean relief seat with a soft, dry cloth. Reassemble in the
reverse order making sure slip ring is properly positioned on top of
the diaphragm. Bonnet torque values are shown in the table
below.
4. Liquid level in the bowl must be kept below the level indicator line as
marked. It is recommended practice to drain a unit equipped with the
manual drain at least once during an eight (8) hour period. To do so,
rotate the drain knob to the left one or two turns.*
5. Before returning unit to service, insure that all seals have been properly
reinstalled or replaced and components requiring torque have been
properly tightened. Also, insure that bowl seal O-ring and bowl have
been installed properly and that the bowl is in the locked position and
the drain is properly secured.
TROUBLESHOOTING LEAKS
1. If regulated pressure begins to creep, an uncontrolled rise in regulated
pressure, it will most likely be caused by contamination on the valve
seat. Refer to Maintenance Step #2, Valve Assembly to remedy the
condition.
2. If the unit leaks from the vent holes in the bonnet, it may be caused by
contamination on the diaphragm relief seat, seal deterioration of relief
seat or diaphragm damage. Refer to Steps #2 and #3 under maintenance
to remedy the condition. Replace all damaged or worn components.
*NOTE: In the event the drain knob is over-rotated, it may become
disengaged from the drain stem. In such a case, pull down on
both the knob and the stem while rotating clockwise to re-engage.
(viewed from below.)
ACCESSORIES
Joiner set ............................................................................. GPA-96-601
T-Bracket .............................................................................. GPA-96-602
T-Bracket with Joiner set ...................................................... GPA-96-603
L-Bracket (B18).................................................................... GPA-96-606
L-Bracket (B28).................................................................... GPA-96-607
Pressure Gauges:
0-30 PSI, 1/4 NPT ............................................................ K4515N14030
0-60 PSI, 1/4 NPT ............................................................ K4515K14060
0-160 PSI, 1/4 NPT .......................................................... K4515N14160
0-300, 1/4 NPT ................................................................. K4515N14300
0-2.0 bar, 1/4 BSPP .......................................................... K4515G14030
0-4.2 bar, 1/4 BSPP .......................................................... K4515G14060
0-11.2 bar, 1/4 BSPP ........................................................ K4515G14160
0-21 bar, 1/4 BSPP ........................................................... K4515G14290
Drains
Manual Drain ....................................................................... GRP-96-685
Automatic Mechanical Drain (Nitrile) ................................... GRP-95-973
Automatic Drain (Fluorocarbon)........................................... GRP-95-981
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