LowFlow JBDL Series Back Pressure Valves - Manual (Page 2)

knob (3) counter-clockwise (CCW) until there is no
noticeable spring tension.
3. Slowly open the inlet block valve. Note: if no bypass
valve is installed, extra caution should be used in
starting up a cold system; i.e. do everything slowly.
4. Slowly open the outlet (downstream) block valve.
5. Slowly rotate the regulator adjusting knob (3) clock-
wise (CW) until flow begins.
6. Develop system flow to a level near its expected nor-
mal rate, and reset the regulator set point by turning
the adjusting knob (3) CW to increase inlet pressure,
or CCW to reduce inlet pressure.
7. Reduce system flow to a minimum level and observe
set point. Inlet pressure will rise from the set point of
Step 6.
Shutdown
1. On systems with a bypass valve, and where sys-
tem pressure is to be maintained as the regulator
is shutdown, slowly open the bypass valve while
closing the inlet (upstream) block valve. (When on
bypass, the system pressure must be constantly
observed and manually regulated.) CAUTION! Do
not walk away and leave a bypassed regulator
unattended.
2. If the regulator and system are to both be shut
down, slowly close the inlet (upstream) block valve.
Close the outlet (downstream) valve only if regulator
removal is required.
Maintenance
Standard Repair Kit Parts are identified on the parts
listing by an ** after the item number. LowFLow Valve
recommends that all of these parts be replaced during
servicing.
Warning! System Under Pressure. Prior to perform-
ing any maintenance, isolate the regulator from the
system and relieve all pressure. Failure to do so could
result in personal injury.
A. General
1.
Maintenance procedures can be done after re-
moval of the regulator unit from the pipeline where
installed; it may be maintained in-line if it is safe to
do so.
2. Always follow local or company procedures for
removal, handling, cleaning, and disposal of non-
reuseable parts, i.e. gaskets, etc.
B. Trim Replacement
1. Remove adjusting knob (3) completely from the
spring housing (2).
2. If valve is removed from the line, clamp the valve
body in a vise upside down. Remove the bottom cap
(9), seat holder (11), and seat (10). Discard the seat
(10). Place body right-side up and clamp in vise again.
3. Remove spring housing (2), spring guide (5), and
range spring (4).
4. Remove diaphragm assembly parts (6), (8), (7), (12),
and (13). See Figure 2.
5. Unscrew the lower diaphragm plate (7) from the up-
per diaphragm plate (6). Discard the old diaphragm
(8) and replace with new one. Remove and replace
the backup ring (16) and o-ring (15) off of the plug.
Inspect remaining parts of the diaphragm assembly
and replace if necessary and reassemble. Note: Use
only parts manufactured and supplied by LowFlow
Valve for these parts.
6. Place diaphragm assembly (6), (8), (7), (12), and (13)
back into the body cavity (1).
7. Replace range spring (4) and spring guide (5) on top
of the upper diaphragm plate (6). Replace the spring
housing (2) and knob assembly (3).
8. Reorient the valve so it is upside down again.
9. Place the new soft seat (10) into the seat holder (11)
and put back into the bottom of the body (1).
10. Remove the o-ring (14) from the bottom cap and
install the replacement.
11. Install the bottom cap (9) back into the body cavity (1).
Figure 2. Diaphragm Subassembly
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