6. The instrument reading will move up the scale (wetter), and stabilise. When there is no further change in reading, note the result. If the reading move up the scale (wetter) and then move down the scale (drier) the either the sample pipe was not purged enough before the head was raised, or the sample is becoming drier during the test. (Perhaps by taking the sample from a pipe in which the gas has been stagnant for some time).
If in doubt about the suitability of the sample flow rate, or the materials of the sample pipe being used, increase the sample flow rate after the final reading has been obtained. If the instrument moves to a drier reading this indicates that the original flow rate was too low, or that there is a leak in the system allowing ambient moisture into the sample, or that the sample pipe itself is still wet.