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Linearity
To test linearity, at least 3 test weights are used. Each weight represents a different test
rate. Record the integrator rate display value associated with each test weight applied to
the flowmeter.
If all the recorded display values are accurate, the flowmeter measurement is linear.
e.g. For an E-300 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 non-
linear, ensure there is no air circulation in the housing sensing plate area. If there is no
significant air circulation in the flowmeter housing while 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.
Note:
Electronic linearization should not be used to correct non-linear test weight
results.
7ML19985CX01
Milltronics ILE-61 – INSTRUCTION MANUAL
Page 15
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