The Lee Co. (Industrial Microhydraulics Div.) offers miniature pressure relief valves for metal and plastic applications. Pressure relief valves for installation into metal are available in forward and reverse flow directions in two sizes: 5.5mm and 8.0mm. Pressure relief valves for installation into plastics feature simple, press-in installation. These valves are available in 2.5, 5.5, and 8.0mm (with corresponding flow capabilities).

Anver Corp. offers adjustable miniature vacuum relief valves with optimum flow design for vacuum applications. Vacuum relief valves are spring loaded and adjust from 6" Hg to 27" Hg. Valves come with a nickel plated steel body and a stainless steel spring.

Pnue-Hydro Products offers miniature pressure relief valves. These valves provide zero leakage up to cracking pressure, and adjustments are insensitive to temperature variations. Valves are made from 316 stainless steel, Buna-N, and Viton materials. Available operating pressure ranges start at 50 psid and go as high as 13,000 psid. Operating temperature ranges from as low as -20° up to 450°F.

Parker Hannifin Corp. offers ISYS micro valves for a variety of applications, including automated assembly, process control, alternative energy systems, packaging, semiconductor, fixturing systems, dairy systems and water treatment systems. Available configurations include: 25 Pin D-sub Connections for smaller machines, Moduflex Fieldbus for larger machines, and Isysnet Fieldbus for large, complex machines.

Sigma-Aldrich Co. LLC offers micro-valves for applications in need of pressure relief/control. Valves come in two forms: micro-meter and micro-splitter. Valves have inert PEEK construction, and flow rates as low as 3.5µL/minute. Fittings are either flangeless or fingertight, and are available as 1/4-28 or 10-32. Maximum pressure available ranges from 800 to 4000 psi.

Circle Valve Technologies, Inc. is a distributor of valve products from a variety of manufacturers. Available products include the 500 series miniature relief valve with a popoff or inline design. Miniature relief valves feature adjustable crack pressure, tamper-proof adjustment and sizes from 1/8" to 1 1/4" as well as being constructed from aluminium, brass or stainless steel.