Piston Flowmeters and Industrial Applications

Piston flowmeters are positive displacement flowmeters designed to provide high-accuracy measurement. They measure fluid volume through a reciprocating piston mechanism, making them ideal for low flow rates and high-viscosity fluids. Due to their reliability, they are widely used in chemical, pharmaceutical, food, oil, and automotive industries.

WORKING PRINCIPLE

In piston flowmeters, fluid enters a chamber where a piston moves back and forth. Each piston stroke displaces a fixed volume of fluid, which is then counted by mechanical or electronic sensors. The total volumetric flow rate is determined based on the number of cycles.

Basic equation:
Qv = n · Vc
Qv: volumetric flow rate (m³/s)
n: piston stroke frequency (Hz)
Vc: displaced volume per stroke (m³).

This principle ensures high accuracy, even at very low flow rates, and is less sensitive to pressure fluctuations.

STRUCTURAL FEATURES

• Body materials: stainless steel, aluminum, cast iron
• Measuring element: piston-cylinder mechanism
• Output signals: mechanical register, magnetic pickup, pulse output
• High-pressure resistance
• Low pressure drop and high repeatability

ADVANTAGES AND LIMITATIONS

Advantages:

• Very high accuracy (±0.1% – ±0.5%)
• Effective for low flow measurements
• Reliable for viscous fluids
• Durable and long-lasting design

Limitations:

• Maintenance required due to moving parts
• Reduced lifespan with abrasive or particulate fluids
• Limited use in large-diameter pipelines

APPLICATION AREAS

• Solvent, resin, and polymer measurement in chemical industries
• Precise dosing in pharmaceuticals
• Measurement of syrup, honey, and oils in food industry
• Oil and fuel measurement in automotive industry
• Lubrication systems and hydraulic applications in energy sector

STANDARDS AND CALIBRATION

• OIML R 117: International standard for liquid measuring devices
• ISO/IEC 17025: Calibration laboratory accreditation
• ATEX-certified models for explosive environments
• Regular calibration is essential for maintaining accuracy over time

CONCLUSION

Piston flowmeters are highly reliable in low-flow and high-viscosity conditions. They play a critical role in industries requiring precise dosing and accurate volumetric flow measurement.