Humboldt H-2786 Air Meter - Manual (Page 5)

4
6. Screw curved tube into the outer end of petcock and by pressing
on thumb lever and controlling flow with petcock lever, fill the 5%
calibrating vessel level full of water from the base.
7. Release the air at the free petcock. Open the other pet cock and let
the water in the curved pipe run back into the base. There is now 5%
air in the base.
8. With petcocks open, pump air pressure in exact manner as out
lined in paragraph 4. Close petcocks and immediately press the
thumb lever. Wait a few seconds for exhaust air to warm to normal
temperature, and for the needle to stabilize. The dial should now
read 5%.
9. If two or more consistent tests show that the gauge reads incorrectly
at 5% air in excess of .2% (or whatever is considered satisfactory),
then remove gauge glass and reset the dial hand to 5% by turning
the recalibrating screw.
10. When gauge hand reads correctly at 5%, additional water may be
withdrawn in same manner to check results at 10%, 15%, 20%, etc.
11. The recalibrating screw is located in the center of the pointer.
Maintenance Tips
1. Prompt cleaning with water of the air meter cover and pot, both
inside and out will ensure a proper seal and volume are maintained.
2. Periodic oiling of petcock screws will prevent them from seizing.
WD-40 or a similar product is sufficient.