LowFlow Mark 708SH Series Short Pattern 1/4 - Manual (Page 2)

Remove the actuator from the bonnet. (See Remov- 1.
ing Actuator from Valve.)
Remove all of the packing and discard. Clean valve 2.
stem and packing box thoroughly. The valve stem
may be dressed with a very fine crocus cloth, but
generally it is best not to as the stem has a fine ma-
chined finish. Use approved non-residue-forming
solvent for cleaning. Wipe dry with clean cloth.
Insert a new set of packing in packing box. Press 3.
each ring down in place with a tube as it is in-
stalled.
After packing is installed, assemble packing adapt- 4.
er, gland, and gland nuts. Tighten the nuts hand
tight.
The final packing adjustment should be made with 5.
the valve pressurized and the packing tightened
just enough to stop any leakage, while stroking the
valve. Excessive tightening could cause the stem
to stick and result in improper valve operation
due to high friction forces.
Removing Actuator from Valve
1a. Direct Acting Actuator (ATC): Shut off pressure to
the actuator and remove supply tubing from the
actuator case.
1b. Reverse Acting Actuator (ATO): Apply approxi-
mately 6 psig air pressure to the actuator to lift the
plug off of the seat.
1c. Motor Valve (Mark 708MV): Position the valve to full
open and disconnect all electrical connections.
2. Remove the actuator from the valve as follows:
loosen the two stem connector nuts and move
them down the stem. Lock these nuts together.
Remove the two nuts that secure the packing
flange, then the then the two hex bolts that secure
the yoke to the bonnet. Remove the gland nuts (11)
that secure the packing gland (9) and the packing
adaptor (7). Using a wrench on the nuts and on
the flats of the actuator stem, turn the stem con-
nector (while holding the actuator stem in place)
until the stems disengage. The actuator will be free
of the valve.
Body & Bonnet Disassembly
For actuator removal, refer to section on “Removing 1.
Actuator”.
Remove the body/bonnet bolts and 2. carefully sepa-
rate the body from the bonnet so as not to damage
delicate trim components.
Remove stem nuts and indicator. Withdraw the 3.
stem and plug out of the bonnet. (The smaller trims
have a one-piece stem and plug, which can be
withdrawn through the packing.)
With a socket wrench, remove the seat from the 4.
body. Remove and discard the body/bonnet gas-
ket.
Soft seats are disassembled by removing the seat 5.
cap from the seat and then the soft seat can be
removed.
The control valve has been pre-set by Jordan Valve, 2.
however, finer adjustment may be required to com-
pensate for the system conditions of your applica-
tion.
With inlet, outlet and bypass shutoff valves closed, 3.
and no pressure in the down stream line, fully
open the outlet valve. Slowly open the inlet valve
just enough to start flow through the control valve.
Increase the flow gradually by slowly opening the
inlet shutoff valve. Do not fully open the inlet valve
until you are sure that the controller and control
valve have control of the system. Usually, the
handwheel on the inlet valve will turn freely when
this point is reached.
To shut off the line fluid, close the inlet shutoff 4.
valve first, and then close the outlet shutoff valve.
Maintenance
Caution: Make certain that there in no pressure in the
valve before loosening any fittings or joints. The fol-
lowing steps are recommended:
Close the inlet shutoff valve. 1.
Allow pressure to bleed off through the down- 2.
stream piping. Do not attempt to reverse the flow
through the valve by bleeding pressure from the
upstream side of the valve.
When the pressure gauges indicate that all pres- 3.
sure has been removed from the system, close the
outlet shutoff valve, and the valve may be serviced.
Note: refer to the drawing at the end of this docu-
ment for description and proper orientation of parts.
To reduce maintenance time, refer to proper figure and
follow steps indicated below for applicable maintenance
operation.
Proposed Maintenance
Procedure
Follow Steps...
Renewing Stem Packing Packing Replacement
Valve Disassembly,
Inspecting Parts, Replacing
Plug or Seat Ring
Valve Disassembly
Valve Reassembly Valve Reassembly
Actuator Spring Preload
Adjustment
Actuator Spring Load
Adjustment
Actuator Maintenance Actuator Maintenance
Motor Valve Seat Spring
Preload
Motor Valve Seat Spring
Preload
Packing Replacement
Renew valve plug stem packing if control valve has been
in service beyond normal maintenance, and packing
shows signs of wear. Wear will be indicated by leakage,
which cannot be corrected by minor tightening of the
packing flange. An additional packing ring can be in-
stalled to overcome minor leakage without dismantling
the control valve or breaking valve plug connection.
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