301/303/305/306/307 Flowmeters and Controllers Instruction Manual
EAR99 Technology Subject to Restrictions Contained on the Cover Page
Page 17 of 32
If the system pressure is higher than 250 psig (1.7 MPa) the pressure induced error in the span reading
becomes significant. This error will approach 16% for nitrogen at 1000 psig. For accurate high-pressure
measurements this error must be corrected.
The formula for predicting the nitrogen mean error expressed as a fraction of the reading are:
Sensor Type
A
B
0.026”
-2.2915*10
-7
5.7198*10
-5
0.017”
-7.1066*10
-8
5.2403*10
-5
0.014”
-5.3091*10
-8
6.1278*10
-5
𝐸𝑟𝑟𝑜𝑟
= 𝐴𝑃 + 𝐵𝑃
Where P is the pressure in psig and
Error
is the fraction of the reading in error.
The flow reading can be corrected as follows:
𝐶𝑜𝑟𝑟𝑒𝑐𝑡𝑒𝑑 = 𝐼𝑛𝑑𝑖𝑐𝑎𝑡𝑖𝑜𝑛 − (𝐼𝑛𝑑𝑖𝑐𝑎𝑡𝑖𝑜𝑛 × 𝐸𝑟𝑟𝑜𝑟)
Where the
Indication
is the indicated flow and
Error
is the result of the previous formula (or read from
charts above).