Thermo Scientific Sarasota FD900, User Manual

Page: 45 / 94

Thermo Fisher Scientific User Guide for Sarasota ID900, FD900, & PD900 Gas Density Meters
4-3
Temperature
Correction at
Check Points
Calibration
Temperature Correction at Check Points
The temperature coefficient for units fitted with Ni-Span C spools
(maximum 75°C/167°F) is so small that Tair or Tvac checks can be made
without correcting for the difference between the temperature of the check
and the temperature during the calibration Tair/Tvac .
When high temperature spools (above 75°C/167°F) are fitted, it is
advisable to make the following correction when doing Tair or Tvac
checks:
where
T
corr
= T
m
+ T
cof
* (
θ
1 -
θ
2)
Tm = time period in
µ
s measured at check conditions
Tcof = temperature coefficient of transducer in
µ
s from calibration
certificate
θ
1 = temperature of Tvac or Tair on calibration certificate (°C)
θ
2 = temperature of instrument at time of vacuum point check (°C)