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Diaphragm Replacement
A. DISASSEMBLY
1.
Remove all of the compression from the spring (7)
by rotating the adjusting screw (1) counterclock-
wise until it moves freely.
(Failure to remove the
compression from the spring could result in per-
sonal injury or damage to the valve.)
2.
Remove the spring housing bolts (5) and spring
housing (4). Remove the spring (7) and spring seat
(6).
3.
Remove the diaphragm assembly by rotating coun-
terclockwise. The diaphragm assembly consists of
the upper diaphragm plate (8), diaphragm (9) and
lower diaphragm plate (10).
4.
If the diaphragm must be replaced, secure the
upper diaphragm plate (8) in a vise. A 3/16” face
spanner wrench should be used to remove the
lower diaphragm plate (10) from the assembly.
5.
Remove the diaphragm (9) and reassemble in re-
verse order.
B. REASSEMBLY AND STROKE ADJUSTMENT
1.
Note that the valve stroke adjustment is deter-
mined by how far the diaphragm assembly is
screwed onto the stem. Screw the diaphragm as-
sembly onto the stem until the disc pin is centered
in the valve body.
2.
Push the diaphragm assembly down against the
valve body and check the orifice alignment of the
disc (17) and the plate (16). The orifices should be
fully open and in perfect alignment.
3.
If the orifices are not in perfect alignment, rotate
the diaphragm assembly counterclockwise to lower
the disc, and clockwise to raise the disc.
4.
The total stroke of the Mark 60 is equal to the ori-
fice width plus 1/32” overlap. Consequently, per-
fect adjustment is required for proper operation.
5.
When seats are in perfect alignment, proceed with
the assembly of the spring housing.
6.
Place the spring (7) on the upper diaphragm plate
(8) and the spring seat (6) on the spring.
7.
If the diaphragm is metal, be sure that the dia-
phragm is aligned in the body recess. This recess
also aligns the spring housing (4). Be sure that the
bleed hole is facing downstream.
8.
If the diaphragm is elastomer, make sure that af-
ter the seats are in perfect alignment that the bolt
holes are in alignment. If an adjustment needs to
be made to align the bolt hole, make the adjust-
ment by turning the diaphragm assembly clock-
wise.
9.
Install and tighten the spring housing bolts (5) per
the torque instructions on the back page.
Stroke Adjustment
1.
The stroke adjustment is made with the spring housing and adjusting
spring removed from the valve.
2.
The valve orifices should be open and in perfect alignment when the
diaphragm assembly is pressed against the valve body as illustrated.
3.
The valve stroke adjustment is determined by how far the stem is
screwed into the diaphragm plate. Rotate the diaphragm assembly to
raise or lower the valve disc. Unthread the diaphragm assembly partially
to lower the disc or thread the stem deeper into the assembly to raise the
disc.
Disc
Cap
Disc Guide
Plate
Disc Pin
Vice
Orifice
Stem
3
Upper
Diaph. Plate
Diaphragm
Lower
Diaph. Plate
1
If Stroke is Too Short:
To correct, turn the diaphragm assembly
toward you (unthreading it from the stem)
bringing the disc orifices into alignment with
the plate orifices.
If Stroke is Too Long:
To correct, turn the diaphragm assembly
away from you (threading it farther onto the
stem) bringing the disc orifices into align-
ment with the plate orifices.
