Humboldt H-2783 Pressure Meter - Manual (Page 4)

Operation Instructions
1. Fill the base with a sample of fresh concrete according to ASTM
C231 specifications. Next, strike off the base level full with the strike
off bar that is furnished with the instrument. Wipe top of base and
cover clean.
2. Clamp cover on securely, with petcocks open.
3. Using the supplied syringe, inject water through one petcock until
all the air is displaced and expelled through the opposite petcock.
Leave petcocks open at the time.
4. With the built-in pump, pump air to the initial pressure line on the
gauge.
5. Wait a few seconds and stabilize hand on dial at the initial pressure
by pumping up or bleeding off with the air release valve, whichever
is necessary.
6. Close both petcocks, then press down on the needle valve lever to
release the air into the base. Hold the needle valve lever down a
few seconds while lightly tapping on the gauge with your finger to
stabilize the hand on the gauge.
7. Read the percent of entrained air in the concrete on the dial.
8. After you release the pressure, clean the base, cover and petcock
openings thoroughly with running water. To check the accuracy,
refer to the calibration instructions below.
To Check Calibration of Meter Gauge
1. Fill the base full with water.
2. Screw on the short piece of straight tubing supplied with the unit
into the threaded petcock hole located on the underside of the
cover. Clamp the cover on the base with the tubing extended down
into the water.
3. With both petcocks open, add water with the syringe through the
petcock until all of the air is forced out of the opposite petcock.
Leave both petcocks open.
4. Pump up air pressure to a little beyond the pre-determined initial
pressure line on the gauge. Wait a few seconds for the compressed
air to cool to normal temperature and then stabilize the gauge hand
at the proper initial pressure line by pumping or bleeding off as
needed.
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