SADP_Operating_ Instructions_0114
4.0 Purging the Sample Connection
Refer to the sample system schematic in section 3.2.
It is advisable to carry out an initial purge of the sample loop, before connecting the
SADP, in order to avoid the possibility of sensor damage on start-up.
Open the sample isolation valve (1) slowly, until a there is a small flow of air/gas at atmospheric
pressure from the pressure reduction valve (4) into SADP line. Allow the air/gas to exhaust through the
sample connection (9).
The SADP 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 8 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.
4.1 Sample Connections
The SADP instrument is supplied with push-on sample connections on each side of the test chamber
(head) of the instrument. These connections are reversible and flow direction is not important. The
fittings are designed for pipe having an internal bore of approximately 6mm (1/4"). Only the PTFE
(Teflon) pipe provided should be used, as other materials are unsuitable. The sample pipe should be
heated in a naked flame for a few seconds before being pushed onto the instrument connection for the
first time. This will provide a good gas-type connection and ensure accurate results.
5.0 Controls
SADP instruments have a single rotary switch to the right of the indicator, which controls the power
supply, the battery check and the range selection (in dual range models) . The switch positions are
marked on the instrument fascia. SADP-D models have a single on/off switch.
