How is level measurement carried out using mechanical differential pressure gauges
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How is level measurement carried out using mechanical differential pressure gauges
The differential pressure gauge measures the amount of negative drift in liquid level; this drift is intended to compensate for the capillary column pressure difference ΔP resulting from the fact that the flange in the negative pressure chamber is at a higher level than the flange in the positive pressure chamber. If the zero point of the gauge is located at the flange in the positive pressure chamber, then the amount of negative drift is ΔP. If the zero point is located h units above the flange in the positive pressure chamber, then the drift amount is ΔP – ρgh. When the controlled liquid level range is H, the measured range after this drift becomes from –(ΔP – ρgh) to –(ΔP – ρgh) + ρgH
Both the DDZ-II and DDZ-III type level transmitters have zero-point adjustment screws. First, perform verification from 0 to 100%, and then adjust the migration. Positive (negative) migration: Apply the pressure required for migration in the positive (negative) pressure chamber, adjust the migration screw to make the output a 0-point signal, and then perform zero-point and range calibration.