barfield 1811D Series, User Instruction Manual, Page: 41 / 64

1811D INSTRUCTION MANUAL
56-101-00164 Rev. F SECTION 4
Apr / 19 / 13 Page 29 of 38
2. RESETTING NEEDLE VALVE POSITIVE STOP
Caution: Before performing the Valve Leak Test or Resetting the Needle Valve Positive
Stop, inspect the entire system for leaks at locations other than valve seats, i.e.,
connections, general plumbing and instruments.
Positive stop spacers are installed on some models to provide a “positive stop” which allows
a firm closing of the valves without damaging the valve needles or their seats. On other
models, the valve body provides this stop. The positive shut-off is carefully set and adjusted
during the manufacturer or factory recalibration. However, if the valves develops a slight
leak from repeated use, do the following steps to reset:
Caution: Except for the pressure and vacuum control valves, any leak seen could be from
a source other than the valves. Do not tighten any valve beyond the closing
point described below. When it is determined that a valve is leaking, correct the
leak before continuing.
A. Firmly close the valve against its positive stop.
(1) With a 5/64" (.078") hex wrench, loosen the knob setscrew.
(2) Raise the knob approximately 1/32" above the valve body or spacer. Retighten the
setscrew.
(3) Gently turn the knob clockwise while ensuring not to exceed one quarter (1/4)
rotation, or until positive resistance is felt.
Caution: Do not exceed one half (1/2) rotation. If the leak persists, the leak is
located elsewhere or the valve is defective.
(4) If doing step (2) above stopped leakage, loosen the knob setscrew and remove
knob.
Note: If spacers are installed, do not remove them.
(5) Locate the setscrew mark, on the valve stem.
(6) Align the setscrew to a new location.
(7) Push the knob firmly down against the valve body or spacer and hold down while
tightening the setscrew.
(8) Open valve one quarter (1/4) rotation, and then close firmly. (A “positive shut” off
should now exist.)
B. If a leak persists, continue testing, and resetting or replacing remaining valves, until no
leakage occurs.