Jordan Valve Mark 75 Series – Wafer Style Control Valve - Manual (Page 4)

preload adjustment may be required after one of the
previous maintenance procedures. Note: valves are
bench set at the factory. To open at 2 psig over the low-
est stated number in the range, please insure that any I/P
utilized with this control valve is capable of sufficient out-
put to ensure full valve travel. If desired, the range may
be changed to suit your needs by following the instruc-
tions bellow.
1. Remove the air signal line from the actuator and re-
place with a pressure gauge and an air regulator.
2. Loosen, but do not remove the Stem Connector
Nut (18), and Lower Jam Nut (20) (under the Anti-
Rotation Device (23).
3. Adjust the actuator air pressure to just below the
starting point of the range and rotate the Actuator
Stem (24) until the stem just starts to move. Contin-
ue to rotate the Actuator Stem about one-half turn.
4. Remove the air pressure. Gradually increase the
air pressure and check at what pressure the valve
stem starts to move. Repeat Actuator Stem Adjust-
ment (step 3) if necessary and again check to see if
the stem starts to move at the desired pressure.
5. After the preload has been properly adjusted,
tighten the Lower Jam Nut (20) and the Stem
Connector Nut (18) and reattach the control air
signal line.
Changing Valve Action
The action of a MK75 may be changed from DIRECT
ACTING to REVERSE ACTING, or vice versa, as follows:
6” Valves - Rotate both the Disc (2) and the Plate (1) to-
gether 180°. Check the valve stroke and orifice alignment
and adjust, if required, as outlined in the Valve Stroke
Adjustment section.
8” - Rotate the Disc (2) on the Plate (1) 180°. Check the
valve stroke and orifice alignment and adjust, if required,
as outlined in the Valve Stroke Adjustment section.
Ordering Spare Parts
Use only genuine Jordan Valve parts to keep your valve
in good working order. So that we can supply the parts,
which were designed for your valve, we must know ex-
actly which product you are using. The only guarantee to
getting the correct replacement parts is to provide your
Jordan Representative with the valve serial number. This
number is located on the valve identification tag. If the
serial number is not available, the parts needed for your
valve might be determined using the following informa-
tion: Model Number, Valve Body Size, Seat Material and
Cv Rating, Spring Range and Set Point, Trim Material, Part
Name - Number and Quantity.
NOTE: Any parts ordered without a valve serial number
that are found to be incorrect are subject to up to a mini-
mum 25% restock charge when returned.
-4-
Adapter Plate (25). Some spring compression
should be felt.
4. Replace the remaining Actuator Bolts and Nuts and
tighten evenly across the actuator case.
5. Reassemble the Actuator Assembly to the Yoke
(10) using the four stroke plate bolts (27).
6. Reconnect the Upper Stem Adapter (19), Jam Nuts
(20), and Anti-Rotation Device (23) to the Valve
Stem (42) using the Stem Connector Halves (13),
the Stem Connector Bolt (7), Lock washer (15) Trav-
el Pointer (14), and Nut (18).
7. Adjust the spring pre-load following the instruc-
tions in the Spring Adjustment section of this I&M.
Valve Stroke Adjustment
1. Loosen the Stem Connector Nut (18) only enough
to allow the Stem Adapter (19) to rotate. DO
NOT REMOVE the Stem Connector (13). Proper
positioning of the Valve Stem (42) and the Stem
Adaptor (19) must be maintained while adjusting
the seats.
2. For Direct Acting (Air to Close) Valves: Loosen jam
nuts (20), turn the Actuator Stem (24) counter-
clockwise until the Range Springs (30) are slightly
compressed. This insures that the Actuator Stem is
in its fully upward position. To confirm that the Ac-
tuator Stem is fully stroked up, check that it cannot
be easily rotated without a wrench.
3. For Reverse Acting (Air to Open) Valves; Apply an
air pressure of approximately 5 psi above the maxi-
mum range pressure (ex. 20 psi for 3-15 psi range)
to the actuator. This insures that the Actuator Stem
(24) is in its full downward position. To confirm that
the Actuator Stem (24) is fully stroked down, check
that it cannot be easily rotated without a wrench.
4. Check the alignment of the orifices in the Disc (48)
and Plate (47). The orifices must be in the open
position and in perfect alignment. If the orifices are
not in proper alignment, loosen the Stem Locknut
(18) and thread the Stem Adapter (19) into, or out
of, the Actuator Stem (24), which will move the Disc
(48) up, or down, on the Plate (47).
5. After the proper alignment has been obtained,
tighten the Jam Nuts (20), and Stem Connector Nut
(18) against the end of the Actuator Stem (19). Re-
check the seat adjustment. Repeat Step 4 if
necessary.
6. Adjust the spring preload if necessary. See the
Spring Adjustment section.
Spring Adjustment
The signal range is preset by Jordan Valve; however,
when the valve is installed this range may shift slightly
due to pressure drops across the valve. Additionally,