Action H: Check offset by opening chamber cap. If pressure is negative (displayed on
instrument schematic), run a new zero offset. See Zero the Pressure Trans-
ducer & Chamber Volume on page10 - 20.
Cause I: Dust filter on 2000 cm
3
unit is clogged or leaking to atmosphere.
Action I: Clean the dust filter. See Clean the Dust Filter on page12 - 9.
Helium drained from tank.
Cause A: Leaks in the gas line connection.
Action A: Pressurize the system. Close, then open the gas cylinder shut-off valve. If the
needle on the pressure gauge falls abruptly, a leak in the gas line connections
may be indicated. Check all gas line connections.
Cause B: Pycnometer was left in Manual mode with all the valves open or the fill valve
open and chamber cap off.
Action B: Close all valves, then attach a new tank of helium.
Unit will not equilibrate, or results are not reproducible.
Cause A: Sample outgassing.
Action A: Prior to analysis, remove moisture and contaminants from the sample. See Pre-
pare and Load a Sample on page6 - 1.
Cause B: Dust filter on 2000 cm
3
unit is clogged or leaking to atmosphere.
Action B: Clean the dust filter. See Clean the Dust Filter on page12 - 9.
Cause C: Defective cap O-ring.
Action C: Check cap O-ring for defects. Regrease or replace the O-ring, if necessary.
Cause D: Debris on valves.
Action D: With manual mode enabled and with the cap installed, open all valves. With
helium flowing through the pycnometer, open and close the expansion valve
repeatedly for approximately one minute. This will remove sample con-
tamination, which may cause a leak, from the valve seat. Repeat the process for
the vent valve with the inlet and expansion valves open.
12 Maintenance and Troubleshooting
AccuPyc II 1345 Operator Manual
134-42851-01 (Rev A) — Jan 2021
12 - 3
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