Siemens SITRANS WFS300 Instrukcja obsługi - Strona 32
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Diagnosing and troubleshooting
8.3 Linearity
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 nut.
• 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 - 100% 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.
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Operating Instructions, 03/2021, A5E32880243-AC
SITRANS WFS300