Back to the Basics: Accuracy and Response Time Requirements

Accuracy and response time are closely related. The purpose of the analyzer system is to produce an alarm before the solvent concentration can increase to an unsafe level. This implies that the alarm is given in sufficient time to take effective corrective action. 

There are two cases to be considered: 

1. the steady-state (time invariant)
2. the transient (dynamic) 

This week let's look at the steady-state:

For the steady state condition the response time of the analyzer is not considered. By definition, the condition is relatively constant, and thus the analyzer has sufficient time to respond.

The minimum steady-state accuracy requirement is based upon analyzer accuracy and the accuracy of the empirical L.F.L. values, including temperature effects. The accuracy must be such that any error which can not be adjusted out of the system causes neither a false alarm or fails to give a reliable alarm.