MASS-STREAM
TM
Instruction Manual D-5100
9.17.111A
– Date of issue: 2017-03
Page 11 off 11
2
BY-PASS MEASUREMENT PRINCIPLE AND CALIBRATION
The instrument’s by-pass flow sensor is operating on a principle of heat transfer by
sensing the ΔT along a heated section of the capillary tube. The ΔT is directly proportional
to the gas mass flow. The heat transfer function between gas mass flow and temperature
difference can be described by the following formula:
ΔT = K · C
p
·
m
ΔT … Temperature difference
K
… Constant factor
C
p
… Specific heat
m
… Mass flow
The calibration is processed with a mass flow controller which functions as a reference.
The controller and the gas inlet pressure forward a defined gas flow, thus a signal of the
sensor can be allocated to each specific mass flow.
Each instrument is calibrated according to the customer’s operation conditions within the
specified accuracy limits. These customer specific information can be found on the
instrument label and the calibration certificate.
