Precision Orifices

A Lean Enterprise Dedicated to Quality

O’Keefe Controls Co. Precision Orifices: The Ultimate Solution when Precision Flow Control is Paramount

Precision Orifices are apertures designed to restrict the flow of air, water, or other fluids. Often circular in shape, precision orifices have tightly controlled diameters, lengths, and inlet and outlet geometries. In some cases, flow rates can be specified instead of orifice diameter allowing the user to customize a precision orifice to best suit their application. This can be particularly important when specifying test standards for leak testing applications.

Precision orifices are available in many materials, including metal, plastic, and synthetic sapphire, just to name a few. This variety of materials allows for precision orifices that meet a wide range of pressure, temperature, chemical compatibility, and weight considerations. Metal orifices often address higher temperature and pressure requirements. Other materials are light-weight and perhaps better suited for handheld instrument applications.

O’Keefe Controls Co. offers a full range of precision orifices that work in a wide variety of applications and environments. Our standard and custom orifices are available in diameters as small as 0.0003 inches. 

Each Part Manufactured to Strict Quality Standards

Precision orifices have the vital function of facilitating accurate flow control and metering, across a broad spectrum of liquid and gas process flows.  Bottom line: you need the parts to work exactly as specified. 

With our customers in mind, we make certain our parts are reliable, repeatable, and offer long-lasting performance in a wide variety of pressure and temperature conditions. 

Precision fabrication ensures optimal operation for the overall system.  At O’Keefe Controls Co., we incorporate the following measures into our production processes to ensure high-quality products:

CAD drawing    Laser marking    Optical measuring
Automated optical inspection   Flow testing

Metal Orifices

Metal orifices provide superior control in a fluid system. Metal orifices can be used with a wide variety of fluids, liquid or gas. They can be used in a wide range of pressure and temperature applications. The different metals available allow for a wide range of chemical configurability.

Typical Applications of Metal Orifices

Precision flow control – gases or liquids

Speed controls – cylinders and actuators

Pneumatic or hydraulic circuits

Flow restriction

Accurate throttling

Snubbers – gages and instruments

Ultrasonic sound sources

Features of Metal Orifices

Wide range of pressures and temperatures

Bi-directional flow

Repeatable orifice size and shape

Predictable flow rate

NIST traceable flow data available

O’Keefe Controls Co. Metal Orifices Connection Options

O’Keefe Controls produces metal orifices in an ever-expanding portfolio of connection options.

1. NPT Connections: NPT hex nipples, adapters, bleed plugs, and 90° elbows.

2. Barb Connections: Dual barb, adapter barbs, and adapter barbs with NPT or 10-32 UNF thread.

3. 10-32 UNF Connections: 10-32 UNF bleed plugs, 10-32 UNF adapters, and 10-32 UNF couplers.

4. SAE Connections: SAE 45° flare adapters and 37° flare adapters.

5. Press-Fit Inserts: Available in a range of outside diameters and length and materials.

6. Push-On Tube Adapters: 10-32 UNF, 1/8” NPT, or 1/4” NPT by 1/8” OD, 5/32” OD, 3/16” OD, 1/4” OD tubing. 

7. Threaded Inserts: 6-32, 8-32, 10-32, 1/4-20, 5/16-18, 3/8-16 threaded inserts and M3, M4, M5, M6, M8, and M10 metric threaded inserts

8. Face Seal Fittings: Gaskets and double male unions.

9. Compression Fittings: NPT x Tube, tube unions, tube union tees, tube adapters, port connectors, and tube stubs.

10. JIC Connections: JIC 37° flare adapters and SAE 45° x NPT adapter.

11. Straight Thread O-Ring Fittings

Call us to ask about Metal Orifices for your application: 203.261.6711

Features of Sapphire Orifices

Sizes ranging from 0.0012” to 0.0252”  in diameter

Chemically inert 

Highly repeatable

Sapphire Orifices

Our sapphire orifices use a synthetic sapphire material to provide stable and accurate flow restriction. This material makes the orifices far more resistant to heat and pressure, as well as the wear and corrosion that can start to weaken other materials over time. Sapphire orifices are available in 32 incremental sizes ranging from 0.0012 inches to 0.0252 inches in diameter.

Typical Applications of Sapphire Orifices

Precision flow control – gases or liquids

Accurate timing in pneumatic or hydraulic circuits

Pressure dividing circuits and pneumatic resistance bridges

Impedance matching

O’Keefe Controls Co. Sapphire Orifices Connection Options

O’Keefe Controls produces metal orifices in an ever-expanding portfolio of connection options.

1. NPT Connections: Brass and stainless steel NPT connections with synthetic sapphire orifices.

2. Barb x 10-32: Orifices with a barb fitting for a tight seal and a maximum pressure of 100 PSIG.

3. Barb x NPT thread: Stainless steel orifices with a barb fitting for a tight seal and a maximum pressure of 100 PSIG.

4. Dual Barb: Connections with two barbs for secure fittings in systems that required barbed connections.

5. 10-32 UNF connections: Brass connections with straight threads available in incremental measurements.

6. SAE Connections -JIC Fitting- 37 Degree Flared Tube
Connections in 304 stainless steel and brass with 100 PSIG maximum fitting pressure and 100 PSID maximum differential pressure.

7. Compression Connections: Connections with compression endings available in 316 stainless steel and incremental measurements.

8. Compression – Tube Union: Tube unions available in
different cylinder sizes in 316 stainless steel.

9. Press-Fit Inserts with various OD’s and lengths.

Call us to ask about Sapphire Orifices for your application: 203.261.6711


O’Keefe Controls Co.’s line of precision MICRO-ORIFICES® are available in stainless steel and brass varieties, in incremental sizes between 0.0003–0.005 inches in diameter. 

MICRO-ORIFICES® are typically used for systems with very low flow rates. The small openings allow for a suitable amount of pressure buildup in the fluid system to facilitate accurate control. The parts offer accurate timing in systems that use pneumatic or hydraulic circuits, as well as precision metering. They can also limit flow.

Typical Applications of MICRO-ORIFICES®

Systems with low flow rates

Systems that use pneumatic or hydraulic circuits

Flow restriction

Leak test standards

Custom flow rates

Calibration standards

Features of Precision MICRO-ORIFICES®

Wide range of pressures and temperatures

Bi-directional flow

Extremely accurate; high performance

Predictable flow rate

NIST traceable flow data available

Optional filter screens available for added protection of the orifice

O’Keefe Controls Co. MICRO-ORIFICES® Connection Options

O’Keefe Controls produces metal orifices in an ever-expanding portfolio of connection options.

1. NPT Connections: Connection pieces with tapered threads that include an internal orifice.

2. 10-32 UNF Connections: Seals made from brass or 303 stainless steel with Viton seals.

3. Barb Connections: Fittings with a barbed tip that can be used with elastomeric tubing.

4. Press-Fit Inserts: Orifices that can be pressed fit into valves or manifolds.

5. Compression Tubes: Smooth tube fittings that can be used with compression fittings.

Call us to ask about MICRO-ORIFICES® for your application: 203.261.6711

Whitepaper - Understanding Standard Conditions in Flow Measurement

For a detailed review of Standard Conditions, see our whitepaper on our Resources page.

Call us to get your technical questions answered: 203.261.6711

Standard Conditions in Flow Measurement

The Standard Cubic Foot

The flow of gases is traditionally measured in volumetric units such as cubic feet, liters or cubic centimeters. However, since gases are compressible fluids, total mass contained in a given volume varies with both the temperature and pressure of the gas. To provide a meaningful reference for volumetric flow measurements, a “standard” set of conditions are defined for temperature and pressure of the gas. Unfortunately, the definition of standard conditions varies slightly in technical disciplines and industry groups. 

Standard Conditions Used By O’Keefe Controls Co.

The flow charts available in our catalogs, website or product level detail present flow data using the standard conditions of 70ºF and 14.7 psia. The instrumentation used in Quality Assurance flow testing or data presentation per customer request is also provided using these same standard conditions: 70ºF and 14.7 psia.

Using Other Standard Conditions? Technical Customer Support Available 

If you are using instrumentation that references other standard conditions, the O’Keefe Controls Co. technical team can assist with temperature or pressure correction factors to ensure alignment of flow values between the two systems.

Our experienced customer service and technical support personnel can also recommend the best material and configurations for your application requirements from our wide range of precision orifices products: Metal Orifices, Sapphire Orifices or MICRO-ORIFICES®. 

Additional Information

Please visit our Resources page for whitepapers and technical information relating to Precision Orifices and flow data.

Whitepaper- Understanding Choked Flow of Gases
Whitepaper - Ultra Precise Flow Data Raises the Bar for Leak Test Standards
technical brief- Liquid Flow Data
technical brief-gas flow

Call us to get your technical questions answered: 203.261.6711

Used Worldwide for Precision Flow Control

Precision orifices manufactured by O’Keefe Controls Co. are designed to ensure accurate, repeatable, and exact flow through the orifice. This enables us to help companies worldwide when precision is most needed in flow control — whether liquid or gas. Our precision orifices pass stringent quality control testing to ensure they operate exactly as specified, with consistent performance. 

With a quality management system that is ISO 9001:2015 registered, all processes are held to the highest standards of quality.  But perhaps of even greater benefit to our customers, the engineers at O’Keefe Controls Co. are technical experts in the field — knowledgeable about not only our products, but also the science behind their use. As such, we are able to assist customers in diverse practical applications across the industrial, analytical and medical sciences landscape. In all we do, we stand proudly by our tagline: If it’s about precision, it’s O’Keefe.