Dwyer TFP-GV - Manual (Page 13)

F-20-TFP-G, pg. 13 of 27
b) Flows Below The Minimum Rated Flow.
Signal outputs may be obtained at flow rates below the minimum specified
for your unit. The amount of flow that may be measured below the minimum
specified varies from unit to unit.
4. Zero Adjustments
It is impossible for there to be any zero drift so zero adjustments are never
required.
5. Recalibration
Please contact Dwyer Customer Service if your flow sensor or flow meter
needs recalibration.
6. Using Flow Sensors Or Flow Meters With Different Gases
The TFP Series For Gases will operate with most gases subject to
compatibility of the wetted parts.
For information about calibrating for
Hydrogen or Helium, contact Dwyer Customer Service.
Units are calibrated with AIR at a pressure of 760mmHg and temperature
of 23°C unless otherwise detailed on the calibration certificate. Using other
gases will affect the calibration. The amount of calibration error will depend
on the characteristics of the gas being flowed.
The flow reading correction factor (or calibration factor) may be
approximately calculated with the following formula:
C
f
= ( S
new
÷ S
current
)
0.3
C
f
= Correction factor
S
new
= Specific gravity of new gas
S
current
= Specific gravity of original calibration gas
A corrected flow reading may then be calculated using the correction factor
as follows:
Corrected Flow = Flow Reading X Correction Factor