The liquid-sealed rotary drum flowmeter is a device that precisely measures the volume of gas by rotating a drum (rotary drum) in a liquid seal (usually water or oil), with the measurement data being directly visible.

• Extremely high precision, can be used as a standard device: This is its core advantage. Due to the precise geometric volume and the absolute sealing of the liquid seal, its accuracy can reach ±0.2% or even ±0.1%, and it is often used in laboratories to calibrate other gas flowmeters.
• Direct measurement of standard volume: The measurement result is directly the gas volume under working conditions, which is very intuitive.
• Insensitive to flow fluctuations: As long as the gas can drive the rotating cylinder, it can accurately measure, suitable for measuring pulsating flow.
• No external power supply required, and the mechanical structure is reliable.

• Calibration and verification of gas flowmeters (core application): metrology institutes, flow laboratories, and calibration workshops of large instrument manufacturers.
• Scientific experiments and research: chemistry, environmental, and combustion laboratories in universities and research institutions.
• Precision measurement in special industries: historically used for trade settlement of urban gas (replaced by more advanced instruments).

The liquid-sealed rotating drum flowmeter is a "living fossil" and "precision benchmark" in the history of flow measurement technology. It represents the pinnacle of mechanical precision manufacturing and the ultimate pursuit of volume standards.