Pressure Indicator; Fails To Illuminate; Constantly Indicates Nearly The Same Pressure - Micromeritics 1305 Operator's Manual

Pressure Indicator

Samples of high specific surface area may contribute an error due to a layer near
the surface that is partly depleted of gas molecules termed the annulus volume.
Volume errors in the range of 0.005 cm
areas of the order of 100 m
powders are possible. The user is advised to undertake a special examination of
this phenomenon so that precise computations may be made for the gas and pow-
der system in use.
Use of gases other than helium will lead to somewhat less accurate results. Dry
nitrogen is usually satisfactory but, in general, the higher the liquefaction tempera-
ture and the larger the molecular weight of a gas, the poorer the accuracy since
nonideal behavior becomes more pronounced.
Pressure Indicator

Fails to Illuminate

Verify that the power cord is plugged into an energized outlet of the proper volt-
age and firmly seated in the power entrance connector of the instrument. Operate
the power switch to the ON position. Unplug the power cord from the instrument
and remove the fuse and inspect it. If these measures do not reveal the source of
the problem, again unplug the power cord and remove the rear panel of the instru-
ment and inspect the connectors inside to determine if any have loosened. Con-
tact your local service representative in the problem persists.

Constantly Indicates Nearly the Same Pressure

During evacuation of samples, the pressure transducer will be internally limited to
an indication of about 1/3 of the positive full-scale range or about -5.000 psig
even though the reading should be -14.700 psig. Although the transducer was in-
tended for positive pressure indications, this will cause no harm to it.
A reading which does not respond to the FILL valve or VENT valve operation
most likely indicates a defective pressure transducer, pressure indicator, or power
supply. Contact your local service representative for resolution.
4-4
Model 1305 Multivolume Pycnometer
3
/g for powders with specific surface
2 3/
/g or 0.05 cm g for 1000 m
2
/g specific surface area
Jun 99