Calculate and record the rotameter set point using temperatures and pressures expected on the day(s) sampling is conducted. These values can be seasonal set points or daily settings.


where:
Isp = sampler rotameter set point flow rate adjustment
5.0 = MiniVol design flow rate, L/min
Pact = ambient barometric pressure, mm Hg
Tact= ambient temperature, EK.
Tstd = standard temperature, 298 EK
Pstd = standard pressure, 760 mm Hg
mvol = slope of the MiniVol flow rate calibration relationship
bvol = intercept of the MiniVol flow rate calibration relationship.

Adjusting the sampler rotameter to seasonal average conditions will help minimize data loss caused by exceeding the MiniVol's design condition specifications.