Authorities require that an analyzer makes “continuous” measurements.
Portable devices used for occasional checks are not recognized. Sequential sampling systems, which take samples from several locations in the dryer, and multiplex the sample stream to a single analyzer, are not recognized.
A reasonable definition of a “continuous” analyzer is that it can detect a sudden increase in solvent concentration in time to make an effective alarm, at any time during the dryer’s operation.
Most analyzer specifications clearly indicate the time needed for the analyzer reading to reach 63% (or 90%) of a final reading, in response to a sudden increase in concentration.
These times are based on the response of the analyzer alone, and do not take into account the following that may be present in the complete analyzer system as installed:
Sample Transport Time:
- sample tubing