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Flow Restrictors

Precision Orifices for Scientific Instruments

Provide Accurate Flow Rates for Scientific Instruments Applications

Lee precision flow restrictors are the most accurate flow orifices available. Each flow restrictor is 100% flow tested to ensure that every part is within +/-5% of its nominal flow rate, providing more consistent system performance and reducing the need for system rework. This provides far more flow accuracy than an orifice specified by hole tolerance. An ordinary hole held to a very tight tolerance will not result in a tight flow tolerance.

To improve accuracy, we offer models that are intended for gas or liquid applications. Gas restrictors are flow tested on clean dry nitrogen and liquid restrictors are tested on distilled water. Acceptance criteria are very high, and each orifice is tested in the direction of use to increase accuracy.

Because our components are used in such a large variety of applications, they’re available in a range of sizes, configurations, and materials. Each configuration is easy to install and guaranteed to provide consistent flow performance with every part.

Insert Style Precision Orifices

Insert style precision orifices are economical, reliable, highly accurate miniature flow restrictors designed for metal housings. Installation is simple using our field-proven controlled expansion principle, which provides retention and a leak-tight seal without threads, O-rings, or adhesive.

Our standard precision orifices are available in 2.5 mm, 5.5 mm, and 8.0 mm body diameters, and in forward and reverse flow directions. All three sizes are available in liquid and gas configurations with a wide range of standard Lohm rates. Integral safety screens are incorporated where the orifice diameter is 0.5 mm (0.020 of an inch) or below. All orifices are 100% flow tested to ensure that every part is within ± 5% of its nominal flow rate. Tighter flow tolerances are available as specials.

Press-In Style Precision Orifices

Designed for plastic housings, fittings, and soft-tubing, our press-in style precision orifices are both reliable and easy to install using our unique barbed design that ensures retention and prevents bypass leakage. These flow restrictors are available in a 2.5 mm diameter that fits in many common plastic medical fittings and come in a variety of materials, providing compatibility with a wide range of fluids and gases. We also offer a medical-grade 316L version that’s ideal for use in scientific instruments. All press-in style orifices are 100% flow tested to ensure that every part is within ± 5% of its nominal flow rate and are available in both forward and reverse flow directions for both liquids and gases.

Support & Resources

Support & Resources from a Team that Speaks Your Language

Partner with The Lee Company and get much more than just a supplier of top-quality fluid control products. Our reliable technical support team is available every step of the way to help you find solutions, maximize productivity, and drive efficiency across your operations. Check out these resources specific to scientific instrument manufacturers to learn more.