What is meant by response time T90?

Document ID

Document ID CO185

Published Date

Published Date 30/04/2018
Question
What is meant by response time T90?
Summary
Briefly defines response time T90
Answer
When an analyte is introduced into a flowing stream, it takes a certain amount of time to reach and be measured by the detector.  T90 is the amount of time that it takes for the detector to measure 90% of the maximum analyte level.  The concept can be understood by considering how hot water travels through piping to a sink.  After the hot water valve is opened, a certain period of time passes before the water flowing from the faucet reaches the maximum temperature.  The time required for the water from the faucet to reach 90% of the maximum temperature at the outlet of the heater is the T90 for that faucet.  T90 is a useful concept for setting instrument flow rates, sampling line configurations, and when a measurement is representative of the process stream.