Purging The Sample Connection; Using The Sadpmini To Take A Moisture Reading - Alpha Moisture Systems SADPmini Instruction Manual

filter must be of the coalescing type with a drain. The filter unit should be positioned
as close to the sample point as practical.
4. Pressure Reduction Valve or Pressure Regulator – the sample is measured at
atmospheric pressure requiring that valve 4 is fitted to the system.
5. Flow Control Valve
6. Sample Connection
7. SADPmini.
8. Flow Indicator – The recommended sample flow is 5 to 20 L/M.
9. Sample Exhaust – The exhaust is vented to atmosphere or returned to an atmospheric
pressure line.

5 Purging the sample connection

Refer to the sample system schematic in section 4.1.
It is advisable to carry out an initial purge of the sample loop, before connecting the
SADPmini, in order to avoid the possibility of sensor damage on start-up.
Open the sample isolation valve (1) slowly, until there is a small flow of air/gas at
atmospheric pressure from the pressure reduction valve (4) into SADPmini line. Allow
the air/gas to exhaust through the sample connection (9).
The SADPmini is not flow sensitive however the sample flow needs to be enough to
purge the sensor head effectively, so anything less than 1 litre/min would mean that the
instrument would take too long to settle to a stable reading. The flow should also not be
so high that the gas velocity could physically damage the sensor or cause backpressure in
the sensor head, so should not exceed about 20 litres/min.
Allow this purge to continue for 2 minutes to remove any residual moisture from the
sample pipe work and components. Check that no liquid or particulate contamination,
which could damage the sensor, is passing through the sample pipe. Directing the sample
onto a piece of white paper (such as a filter paper) will make it easier to see any dust or
oil mist in the sample.

6 Using the SADPmini to take a Moisture Reading

Refer to the sample system schematic in section 4.1.
The first purpose of the SADPmini is to provide a rapid, easy and reliable means of
carrying out moisture content measurements, of gases. To ensure rapid response the
sensor is kept dry by surrounding the sensor with desiccant in the head assembly when it
is not in use.
The SADPmini can display moisture readings in any one of six Engineering Units and
can also display pressure compensated readings. The SADPmini should be setup as
required (See The Setup Menu section) before progressing to take sample readings
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