Siemens SITRANS WFS320 Operating Instructions Manual page 38

Example
For a WF330 flowmeter design rate of 200 TPH, the following three test weights could be used:
● 9000 g (19.82 lb.) = 100% Design Rate = 200 TPH
● 6750 g (14.87 lb.) = 75% Design Rate = 150 TPH
● 4500 g (9.91 lb.) = 50% Design Rate = 100 TPH
If non-linear results are obtained, ensure:
● at no flow, the moving beam does not rest on the zero stop bolt.
● at 150% Design Rate, the moving beam does not reach the full flow stop bolt.
● at 150% Design Rate, the LVDT output does not exceed 1.0 V AC.
● the damper piston does not touch the damper cylinder wall at any flow rate.
● the LVDT core does not touch the inside of the LVDT at any flow rate.
● the viscous damper fluid is free of large air bubbles and the fluid level is correct.
● the range spring operates in compression from 0 - 150% flow rate.
● the sensing head leaf springs are in good condition.
If the test weight linearity test is successful, yet actual material test results are nonlinear, ensure
there is no air circulation in the housing sensing plate area. If there is no significant air circulation
in the flowmeter housing while you are running material, the material flow pattern is probably
non-linear.
Non-linear material flow patterns can often be corrected by minor modifications to the material
infeed, or upstream piping. Some integrators are equipped with a linearization function to
compensate for non-linear material flow patterns. Stand-alone linearizing devices are also
available for this purpose.
Electronic linearization should not be used to correct non-linear test weight results.
SITRANS WFS320
Operating Instructions, 02/2016, A5E32880290-AB
Diagnosing and troubleshooting
8.3 Linearity
37