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bubbles. The air entering the cylinder will gradually empty some of the water out of the cylinder.
b. After exactly one minute, remove the graduated cylinder from the air flow and raise the
cylinder to the surface so that the air/water dividing line inside the cylinder matches the water
level outside the cylinder. The measurement at this point should be between 13 and 25 cc.
c. If the reading is significantly higher than 25 cc, check the O-rings and sealing surfaces
mated to the piston. If the reading is below 13 cc, check the flow control element in the
piston to determine if it has been clogged by grease or other foreign matter. If it is
clogged, the piston must be replaced.
5.4.3 Intermediate Pressure Test
NOTE:
This test determmines the regulator’s lock-up pressure (the pressure put out by the first stage during
a no-flow condition).
1 Attach any Sherwood second stage to one of the low pressure ports and the Sherwood
intermediate pressure gauge (TL119) to another low pressure port. Plug all other ports with
appropriate port plugs.
2. Attach the regulator to a tank valve giving a source pressure of between 2700 and 3500 psig
(186 and 240 Bar).
3. Turn the supply air on
slowly while listening for any unusual air leaks. If any are heard, turn the
air off immediately and determine the source of the leak. If no leaks are found, watch the
pressure gauge reading rise as you continue turning the air on
slowly. It should stop at about
120 psig (8.3 Bar) when the pressure adjusting ring is screwed all the way in.
4. If the pressure gauge continues to rise above 140 psig (9.7 Bar), turn the air supply off
immediately and inspect the regulator to determine the cause.
5. Once the air pressure stops rising, the internal parts should be worked into place by allowing
air to escape from the second stage several times by pushing the purge button.
6. To raise the pressure to the desired final setting, slowly turn the pressure adjusting ring in a
counter-clockwise direction (as seen when looking down at the cap end of the regulator) in 1/8-
turn stages. At the end of each 1/8-turn, push the purge button several times to let the internal
parts work into place to give a true reading.
7. If the pressure goes above the correct reading, turn the pressure adjusting ring clockwise in 1/8
turn increments. Between each 1/8 turn, the purge button of the second stage
must be
depressed to allow the pressure to drop.
8. After the correct pressure has been reached, let the regulator sit for several minutes and then
depress the Purge Button again to check that the regulator returns to the proper pressure.
9. Once the proper pressure has been set, use the 3/32" Allen wrench to tighten the locking Allen
screw . Tighten the screw clockwise only enough to stop the pressure adjusting ring from
being moved by hand.
Do not overtighten. Check the intermediate pressure one more time
after you have tightened the Allen screw.
10.
Never set the output pressure of the first stage above 150 psig (10.3 Bar).
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