Wet Gas Meter Mechanism: How the Rotating Drum Measures Gas Volume, Parts, Diagram and Uses Explained

Posted by Robbie Dickson on

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A wet gas meter uses rotating liquid-sealed compartments to meter discrete gas volume. This calculator converts entered flow and volume per revolution, compares entered flow with a rated value, and applies a declared water-offset screening curve.

Wet Gas Meter Interactive Calculator

Enter volume per revolution, gas flow, rated flow and signed water offset. The error result is a declared screening curve—not a calibration certificate or correction equation.

0°

Ideal drum speed
--
Converted entered flow
--
Declared absolute-offset error screen
--
Entered rated-flow use
--

Equation Used

ideal drum rpm=1000Q/(60Vrev); flow L/min=1000Q/60; rated use=100Q/Qr; declared error screen uses |h|: 0.5|h| to 1 mm, then 0.5+0.75(|h|-1) to 3 mm, then 2+0.8(|h|-3).
The screening curve discards offset sign and is not sourced as a universal wet-meter accuracy law. Actual indicated volume depends on level, temperature, pressure, saturation, leveling and calibration.
  • Volume per revolution is an entered calibration reference.
  • Gas flow and rated flow use the same volumetric conditions.
  • The offset screen uses absolute water-level offset only.
  • The piecewise coefficients are declared calculator assumptions.
  • Temperature, pressure, humidity, saturation, leveling, slip, pulsation and calibration uncertainty are omitted.
FIRGELLI Automations - Interactive Mechanism Calculators
Same mechanism and inputs as the interactive calculator.

Wet-Meter Level Context

A NIST technical paper explains that gas volume per revolution depends on drum-compartment volume and water-surface position, and that careful level adjustment matters. It does not establish this page's piecewise error curve.

What This Calculator Represents

Compare drum speed and flow units. The separate water-level indicator uses assumed coefficients and does not correct measured gas volume.

Flow and Level Comparison

rpm=1000Q/(60Vrev)
L/min=1000Q/60
use=100Q/Qr
screen=f(|h|)

Worked Example

At 5 L/rev and 6 m3/h, ideal drum speed is 20 rpm and flow is 100 L/min. Against 6 m3/h rated flow, use is 100%; a 1 mm offset gives the declared 0.5% screen.

Assumptions and Limits

  • Calculated: ideal drum speed, units, rated ratio and declared offset screen.
  • Illustrated: compartmented drum and water line.
  • Not calculated: calibrated correction, gas state, saturation, leveling, leakage or uncertainty.

Frequently Asked Questions

Is the error screen a calibration curve?

No.

Does offset sign matter here?

No; the calculator uses absolute value.

Is volume per revolution predicted?

No; it is entered.

Are gas conditions corrected?

No.

Does 100% rated use establish accuracy?

No.

Can this certify a meter?

No.

References

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