Appendix 1 – Pumped version
(optional)
The internal pump, when used in conjunction with the external flow plate and
sampling tube, enables the Detective+ to monitor inaccessible atmospheres. It
offers a consistent flowrate and is not fatigued, unlike the manual hand bulb.
Pumped units are fitted with a water trap which requires periodical inspection
and emptying.
The pump mode may be defined within the calibration menu to be either pump
GO or STOP. This enables the instrument to be used in either pumped or dif-
fusion monitoring mode. See the SETTING UP section above for details on how
this can be configured. Additionally, it is possible to control the pump via the
programmable button as described in section 4.2, Configuration Options.
If the STOP pump mode is selected the pump will not run, and the flow plate
and tubing must be removed to enable gas to enter the sensors by diffusion.
If the GO pump mode is selected the pump will now run and the flow plate
should now be fitted. Ensure that flexible tubing connects between the pump
inlet nozzle on the side of the instrument and the outlet (‘BULB’ side) of the
flow plate. The sample tube should be connected to the ‘INLET’ side of the
flow plate.
The pump mode is remembered while the instrument is switched off.
On increasing the length of the sample tube, the response time will be affected
and some gases may be absorbed, e.g. chlorine. Add approximately 1.5 sec-
onds per metre of sample tube for gas to reach the instrument (4 mm I.D.
tube). Be careful not to suck water or dust into the instrument, and avoid
kinking the sample tube. If the flow is blocked for any reason, the pump is
automatically stopped, and the warning message 'PUMP FLOW FAIL' appears
on the display. Attend to the blockage and then restart the pump by pressing
the right hand button. The pump draws power from the Detective+ battery
pack and so reduces the operating time between recharge by approximately 5
hours before the full stop.
When the instrument is being calibrated from a pressurised gas source, the
pump flow plate should be removed and replaced with the calibration flow
plate, so calibration gas is not drawn into the pump.
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