Crowcon Tetra MO7237, User Manual, Page: 20 / 36

Flow sampling Tetra
VI. Flow sampling
Attaching the flow adaptor plate
To perform manual sampling using Tetra, a flow adaptor plate must be fitted
onto the front of the instrument.
1. To fit the flow adaptor plate, slide the top of the flow adaptor
plate into the small recess on the front of the instrument, screw the
thumbscrew until the plate is tightly fitted into place.
2. Attach the sampling tube or flow accessory onto the gas inlet nozzle.
3. Non- Pumped (diffusion) instruments
Attach the aspirator bulb onto the gas outlet nozzle.
4.
To remove the flow adaptor plate, unscrew the thumbscrew and lift
the plate away from the instrument.
Gas in
Gas out
Flow adaptor
The sampling tube supplied is normally a m (ft) length. Longer lengths of sampling
tube can be provided, but will increase the time taken to get a sample from the point
of sampling to the Tetra instrument. When using an extended length of tubing a
response time test is recommended. Gas of known concentration should be sampled
along the full length of tubing to be used and the time taken for the sensor reading to
reach the known gas levels should be noted. This time should be used as the minimum
for sampling before readings should be taken.