Halmi Nozzle (HN)
± 2.00% Uncalibrated Uncertainty
Low Cost, Open Channel Application
- Line Size: 6” to 48”
- Head Loss % of Differential: Low
- Service Life: 25 years plus, depending on materials
Accurate, Defendable Flow Measurement for Open Channel and Free Discharge Applications
The Halmi nozzle (HN) from Primary Flow Signal is a specially engineered open-channel metering device designed for gravity-driven, free discharge flow conditions, such as partially filled pipes discharging into tanks, lagoons, or manholes. It offers a reliable solution for applications where traditional pressurized flow meters are not feasible, including sewage, sludge, and wastewater discharge systems.
Unlike legacy devices like the Parshall flume, the Halmi nozzle was developed with real-world installation constraints in mind. Its design tolerates less-than-ideal upstream and downstream piping conditions, providing maximum installation defendability in non-pressurized systems. Standard accuracy is ±2.0% of maximum flow rate, with calibrated accuracy as tight as ±1.0%, making it suitable for custody transfer and billing scenarios.
The Halmi nozzle is compatible with a variety of secondary instrumentation, including ultrasonic level sensors, pressure transducers, capacitance probes, and visual staff gauges. Each nozzle is bench and flow calibrated to ensure consistent, accurate measurement across sizes, eliminating the need for individual meter recalibration in most cases.
Key Advantages of the Halmi Nozzle:
- Optimized for Open Channel Flow: Designed for free discharge in partially filled, gravity-fed pipes.
- High Accuracy: ±2.0% standard accuracy, ±1.0% when calibrated.
- Installation Flexibility: Performs reliably even with non-ideal upstream and downstream piping.
- Low Head Loss: Reduced energy loss compared to other open-channel flow devices.
- Multiple Readout Options: Compatible with ultrasonic, pressure, capacitance, or manual gauges.
- No Moving Parts: Low maintenance with no risk of mechanical failure.
- Calibrated for Real Flow: Known discharge coefficients ensure accurate measurement across models.
The Halmi nozzle is ideal for gravity-driven, open-channel flow measurement in sewage, sludge, and wastewater systems, including free discharge into tanks, lagoons, and manholes, as well as custody transfer and billing in non-pressurized lines.
Halmi Nozzle Specifications
Uncalibrated: ± 2.00 of max rate
Halmi Nozzle Model Types
Model Types
- HN – Halmi, Nozzle
Halmi Nozzle Materials
Typical material selections for standard applications:
- Carbon Steel
- Stainless Steel
- Fiberglass
Other options for material selection:
- Aluminum
Halmi Nozzle 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
Municipal Wastewater
Halmi nozzles are widely used in municipal wastewater systems for measuring open-channel flow in gravity-fed sewer lines, manholes, and free discharge points. Their dependable accuracy and low head loss make them ideal for treatment plant influent, effluent, and sewer bypass monitoring.
Water & Environmental Utilities
In water utilities and environmental monitoring programs, Halmi nozzles provide reliable open-channel flow measurement for raw water discharge, stormwater runoff, and treated water entering storage basins or lagoons. Their ability to perform in partially filled, non-pressurized pipes supports regulatory compliance and system optimization.
Industrial Wastewater & Sludge Systems
Industrial facilities use Halmi nozzles to monitor sludge and wastewater discharge from manufacturing and processing operations. Their rugged design performs well in harsh, solids-laden flow conditions and supports flow accountability in on-site treatment or pre-treatment systems.
Agriculture & Food Processing
Halmi nozzles offer a practical solution for open-channel flow monitoring in agricultural runoff, lagoon discharge, and wastewater flows in food and beverage production. Their no-moving-parts design helps prevent fouling and ensures long-term measurement stability in high-organic-load environments.
Industry-Leading Halmi Nozzle Supplier Since 1983
Four Decades of Proven Performance in Challenging Installs
PFS has over 40 years of experience with industry-leading accuracy and reliability. The Halmi nozzle was developed by PFS to solve tough open-channel and free discharge flow challenges. Our meters are trusted in real-world conditions where other devices fail.
Responsive, Expert Engineering Support
From initial design through installation and verification, PFS delivers hands-on engineering support. We help ensure accurate, defensible flow data—especially in utility billing and compliance applications.
End-to-End Manufacturing & Calibration
PFS provides complete in-house engineering, fabrication, and NIST-traceable calibration. Every Halmi Nozzle is built and tested under one roof to ensure performance and quality from start to finish.
