LowFlow Mark 708ME Series with Motor Valve - Manual (Page 3)

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gaskets. DO NOT attempt to resurface seating sur-
faces of the plug or seat. Seats and plugs are only
sold in factory-matched sets.
Valve Reassembly
1. Soft seated valves: insert soft seat into the seat
cavity, install the seat cap and tighten.
2. Lubricate the seat threads with a lubricant such as
NO-LOK and thread the seat into the body. Torque
to values shown.
Valve Size
Seat Torque
ft. - lbs. in. - lbs.
3/4” 26 310
1/2” 20 240
3. Guided trim: Assemble plug to stem.
4. Insert the stem into the bonnet. Set the gasket
around the boss on the bonnet. Carefully assemble
the bonnet to the body and allow the plug to center
into the seat. Push down on the stem to be sure
that the plug has fully engaged the seat. Hand-
tighten the body bolts.
Valve Size Gasket Material Quantity Required
All Tefl on 1
1/2” & 3/4” Grafoil 2
5. Remove and replace the packing as described in
“Packing Replacement”.
6. While holding the plug fi rmly in position in the
seat, secure the body to the bonnet with the bolts.
Torque bolts evenly to the values shown.
Torque Values (in. - lbs.)
Material
Bolt Diameter
Limitation
5/16” 3/8”
Gr. BD* 125 200 650 deg. (also SAE GR. 8)
Gr. B7 125 200 1000 deg. F
Gr. B6 125 200 900 deg. F (410 SST)
* Standard Bolting
7. Reassemble the two stem nuts and indicator all
the way onto the stem threads. Lock the two nuts
together.
8. Position to full open.
9. Mount the motor actuator support legs to the bon-
net fl ange and secure with the hex nuts. Thread
the stem into the motor actuator stem. Hold the
actuator stem with a wrench to prevent it from turn-
ing.
Motor Valve Seat Spring Preload
1. Position the valve to be full open.
2. The two stem nuts should be loosened and thread-
ed down the stem and then locked together.
3. Slowly stroke the motor to closed position, while
rotating valve stem and stem nuts back and forth
(approximately ¼ turn). Caution: valve stem should
rotate freely. When it no longer rotates freely, the
plug is in contact with the seat, and the motor must
be stopped or damage may occur. If required, the
valve stem may be threaded into the actuator stem
to allow motor to complete stroke.
4. With motor in full closed position and stopped by
limit switch, rotate the stem down until the plug is
in contact with the seat, and turn and additional ¼
- ½ turn to preload the seat.
5. Position motor to open position, and confi rm that
the motor is stopped by the limit switch prior to
the plug reaching the upper stop. Without rotating
the stem, thread the stem nuts up and lock them
against the actuator stem.
Note: limit switches and high/low set points are
factory-set. If command signal range will not fully
stroke the valve, refer to electrical connection dia-
gram for the motor actuator that was shipped with
the valve. With seat spring preload set, if plug hits
upper stop prior to limit switch, the limit switch will
require adjustment; consult factory for procedure.