PBI CheckMate 3 - Explanation of the Response Time (T 95 )

PBI-Dansensor A/S COPYRIGHT © PBI-300042-B 10/2010
CheckMate 3 EN User Guide 19
Explanation of the “Response time (T
95
)”
NOTE! Only valid for devices with an Electro-chemical (EC) O
2
sensor.
According to the specifications the Electro-chemical (EC) O
2
sensor has a Response time
(T
95
) of 7 sec.
This means that when performing consecutive measurements in areas with large
differences in the O
2
concentrations, the device will as a minimum reach 95% of the “true”
value during the first measurement (7 sec.).
Example:
(See illustration below):
• Last measurement was performed in i.e. 20.9% O
2
• The following value to be measured is 1.0% O
2
• Difference is:
20.9 - 1.0 = 19.9% O
2
• The expected read-out value after first measuring is:
20.9 - (0.95 * 19.9) = 2.0% O
2
Consequently this means that if there is a large difference in the O
2
concentrations between
two consecutive measurements, multiple measurements must be performed to obtain a
more accurate result.
O reading
[%]
2
time [sec]
T=0
Start value
Difference = Start value "True" value
T valu
95
e = Start value (0.95*Difference)
T value
95
"True" value
T=7
(1. measurement) (2. measurement)
T=14
Difference