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5.0. OPERATION
Ensure that a dust filter is connected in line ahead of this instrument flow inlet in use. The following
steps are necessary and sufficient to operate the instrument:
1. Set measurement alarm level to desired value.
2. Rotate mode switch to “MEASURE”. The “low flow” LED will flash, since the pump is inactive.
The “mute” switch will silence the intermittent tone if desired.
Allow 30 seconds for the instrument to be ready to sample.
Allow an additional two to three
minutes for the instrument to stabilize.
Readjust (if necessary) by turning OFFSET control knob
to achieve a zero reading on the meter
NOTE:
The rotation direction for the adjustment is clockwise for change in a positive
direction. Use very small amounts of rotation, the display will not react
immediately because there is a 30 second time constant.
The instrument is now ready for use. In this mode the ionization chambers are active, but the pump
is not. The instrument is in a so-called “standby mode” ready to sample the instant the mode
switch is advanced to the next position.
3. Rotate the mode switch to the sample position. Now, the pump is operating and the low flow
indication will be eliminated.
If it is desired to operate the instrument continuously on an external power supply, only a source
of 3.3VDC, 1.2-3A current capacity should be used. Attaching the external power plug will
automatically disconnect the D-cell batteries.
NOTE:
If the audible alarm is an intermittent tone, sample flow through the chambers is
below specification. This could be an obstructed sampling hose or other
It is IMPERATIVE that the sample stream be free from dust, dirt or moisture. Not only will the
instrument show erratic behavior, but also it may cease to function entirely. If moisture is ingested,
then continued pumping to evaporate and expel the moisture can be attempted. If this fails, the
instrument must be returned to the factory for service.
Condensation can occur if an instrument is brought from a cold environment into warmer
surroundings.
Furthermore, temperature changes to the instrument, both lower to higher as well as higher to
lower will create transient currents in the electrometer which can appear as large phantom
measurement signals.
The instrument must be allowed to thermally equilibrate to its surroundings prior to use. When
there is an OFFSET due to thermal disequilibrium, use the following procedure:
