Fabricated Venturi Low Flow Meter (FV-LF)
± 0.50% Uncalibrated Uncertainty
Low Reynolds, Lower Loss
- Line Size: 3/8” to 12”
- Head Loss % of Differential: 20.0 to 40.0 percent
- Recommended Pipe Reynolds Number: Greater than 6,000
Ultra Low Flow Meters for Precision Flow Measurement
The fabricated Venturi low flow meter (FV-LF) from Primary Flow Signal is purpose-built for accurate flow measurement in low Reynolds number conditions, combining the performance stability of a Venturi meter with the low-end sensitivity of an orifice plate. Engineered to extend measurement capabilities down to 6,000 Reynolds, the FV-LF is based on our proven HVT design, which performs reliably down to 75,000 Reynolds.
By integrating a carefully shaped inlet and outlet profile, the FV-LF achieves exceptional low flow stability while still offering pressure recovery in the outlet section, resulting in significantly less permanent pressure loss than a traditional orifice meter. This makes it ideal for systems where low flow measurement is critical but pressure drop must still be minimized.
With no moving parts, no annular chambers, and minimal installation effects, the FV-LF offers long-term reliability, low maintenance, and consistent accuracy, even in challenging operating conditions.
Low Flow Meter Advantages:
- Accurate Low Flow Performance: Measures flow accurately at Reynolds numbers as low as 6,000.
- Minimal Pressure Loss: Retains pressure recovery advantages of Venturi meters while outperforming orifice plates in overall efficiency.
- High Turndown Capability: Supports turndown ratios of 10:1, 20:1, 50:1 or more, depending on meter design and instrumentation.
- Maintenance Free Design: No moving parts or annular chambers; eliminates risk of mechanical wear or plugging.
- Minimal Installation Sensitivity: No downstream installation effects and only minimal upstream straight run requirements.
- Flexible Mounting: Installs in any orientation without performance degradation.
- Enhanced Abrasion Resistance: Plasma spray treatment available for added durability in abrasive flow applications.
- Stable, Repeatable Measurements: Ideal for applications where precision at low flow rates is essential.
The FV-LF meter is ideal for low flow measurement in applications such as raw and reclaimed water systems, wellfields, water treatment plants, pumping stations, industrial processes, commercial systems, and oil and gas operations.
Low Flow Meter Specifications
Calibrated: ± 0.25
Uncalibrated: ± 0.50
Low Flow Meter Model Types
Model Types
- FVFLF – Fabricated Venturi, Flanged, Low Flow
- FVWLF – Fabricated Venturi, Butt Weld Ends, Low Flow
- FVTLF – Fabricated Venturi, Threaded, Low Flow
- FILF – Fabricated, Insert, Low Flow Meter
Low Flow Meter Materials
Typical material selections for standard applications:
- Carbon Steel
- 304/316 Stainless Steel
- Chrome Moly
Other options for material selection:
- Aluminum
- Zirconium
- Hastelloy B & C
- Monel
- Duplex Stainless Steel
- Titanium
- Tantalum
- 321 Stainless Steel
Low Flow Meter Certifications
PFS is a contributor to various international standards committees, fully supporting our staff’s memberships to these commissions.
Individual products follow relevant industry regulations, including requirements specific to the oil and gas, water/wastewater, and power generation industries.
PFS maintains the following certifications, standards & compliances:
- ISO 9001
- AGA
- ASME S & U
- API
- ANSI
- European Pressure Equipment Directive (PED)
Applications
Water & Wastewater / Distribution & Billing
FV-LF meters are well-suited for raw and reclaimed water systems, treatment plant influent and effluent, and municipal distribution networks. Their low-flow accuracy and wide turndown ratios support reliable performance in both process control and utility billing applications, even under variable or off-peak flow conditions.
Oil & Gas
In oil and gas applications, FV-LF meters accurately measure low-flow liquids and gases in process, metering, or sampling lines. Their ability to maintain accuracy at low Reynolds numbers makes them a strong choice for auxiliary or intermittent flow points.
Industrial
FV-LF meters are used in industrial systems requiring reliable low-flow measurement of clean or slightly contaminated fluids. The meter’s no-moving-parts design and resistance to fouling support long-term performance with minimal upkeep.
Industry-Leading Low Flow Meter Supplier Since 1983
Over 40 Years of Proven Expertise
With four decades of experience in differential pressure flow measurement, PFS delivers low-flow solutions that perform in the most demanding conditions. The FV-LF builds on our legacy of innovation and field-proven reliability.
Full-Service Support from Design to Installation
PFS offers comprehensive support for every FV-LF meter, including flow calculations, application engineering, calibration, and field training. Our experts ensure accurate, reliable low-flow measurement from start to finish.
Certified Quality You Can Trust
PFS holds ISO 9001, ASME S & U, and PED certifications, with CRN available. Our FV-LF meters are built to meet the strict accuracy and compliance requirements of regulated and defensible flow applications.
