Circle Valve Technologies, Inc. produces relief valves in various series. The 500 series of relief valves includes 334 pop-off or inline valves with zero leakage, adjustable crack pressure,  accurate set pressure, and optional factory preset. The HP500 series of relief valves includes features zero leakage, accurate cracking pressure and tamper proof adjustment.

Simtech provides pressure relief valves in four configurations. The RMR Series pressure relief valve is a two port valve that relieves excess pressure in the line or system. The RNL Series no-lube pressure relief valve offers the same features as the RMR Series in a "no lube" configuration.

Gadren Machine Company offers vacuum relief valves for steam vessel, low pressure tank, and other vacuum equipment applications. These valves come in sizes ranging from 1/4" to 3", flow ratings ranging from 5 to 150 scfm, and mercury release ranges from 7" to 27". They are constructed from solid bar stock 316 stainless steel or brass materials.

Georg Fischer produces pressure control valves such as pressure retaining control valves, pressure reducing control valves and pressure relief valves. Pressure retaining valve selection includes V186 and V86 standard pressure retaining valves and V786 high performance pressure retaining valves.

Parker produces medium pressure valves in various configurations and stainless steel body materials. Pressure relief valves include the LPRA medium pressure valves in three models and the MPR series of relief valves. The MPR relief valves are offered in 1/4, 1/2, 9/16 and 3/4 inch sizes with pressure rating as 3705, 7800, 15000, and 20000 psig.

Automated Valve & Equipment offers pressure regulating valves and back pressure relief valves. Suited for steam, air and liquid applications, pressure regulating valves are offered in bronze, cast-iron and ductile-iron body materials and features inlet pressures up to 450 psig and threaded and flanged connections.

Plast-O-Matic Valves, Inc. offers flow control valves and relief valves. Flow control valves manage constant flow with inlet pressure changes from 15 to 120 psi and standard flow ranges from 1/4 GPM to 120 GPM for corrosive and ultra pure liquid applications. Flow control valves are available in sizes such as 1/4", 3/8", 1/2", 3/4", 1", 1¼", 1½", 2" and 3". True Blue relief valves provide by-pass flow relief in a wide range of pressure settings, fail-dry safety feature and no wetted materials. Series RVD features angle pattern relief valves with a single flat elastomer diaphragm in PVC, Kynar® PVDF, Natural Polypro, & PTFE and in sizes 1/4" & 1/2". Series RVDM features relief valves with a primary rolling diaphragms and a secondary flat diaphragm with a Fail-Dry design in sizes 1/2, 3/4 and 1 inch. Series RVT features an angle pattern design with a smooth PTFE shaft. Series RVDT features an in line design, primary PTFE diaphragm and a secondary support diaphragm. Series TRVDT features a 3 port design and PTFE diaphragm seal. Series RVTX features an angle pattern design, a solid Geon shaft and PTFE thrust washer.

Valv-Trol specializes in standard and custom high pressure valves for water hydraulics and other high pressure water systems. Their back pressure relief valves have a pressure rating of 300 to 25,000 PSI and come in sizes 1/2" to 2". These relief valves are designed specifically to regulate the discharge pressure of a positive displacement pump. The relief valve comes with a precision air regulator or pressure transducer and does not require any outside controller or feedback loop.

Diller Brown carries pressure control and pressure relief valves from CLA-VAL, as well as automatic pump control valves, electronic interface control valves, check valves, and anti-cavitation valves from CLA-VAL. In addition, they carry valves from Tyco, Crane, Pratt, and Proco.

Generant offers the Series QA pressure regulator and control valve, made of brass construction, spring reference, and a fully balanced internally piloted relieving regulator with a 180 degree adjustment quick acting knob set to manipulate outlet pressure from 0 to full line pressure. These control valves have a maximum inlet pressure of 400PSI, and ranges in sizes from 3/8" to 1/2" NPT, in 2 or 4 port configurations. Generant also offers vent relief valves (also available in high pressure configurations), high pressure relief valves, cryogenic relief valves, liquid cylinder valves, and inline relief valves.

Proportion Air makes pneumatic pressure control valves, including electro-pneumatic valves, closed loop valves, high flow valves, and high resolution valves. Their high res control valves have a pressure range of 0 to 150psig with output pressure from 0-100% of the range and 40 micron actual filtration, and wetted elastomers made of Buna N, an aluminum nickel plated manifold, and Utem 1000 aluminum P. transducer.

Thorco makes pressure/vacuum relief valves, emergency pressure relief valves, and pilot operated relief valves. Their 2300A emergency relief valve comes in sizes of 2 to 12", with pressure settings of 0.5oz per inches squared up to 15PSIG, in aluminum 356, carbon steel, stainless steel and other types of construction.

Watts makes pressure relief, sustaining, and backpressure control valves, including the S-116 valve, with optional solenoid. This relief valve comes in full port or reduced port models, with an operating pressure for the 150 flanged type at 250PSI, and the 300 flanged model at 400 psi. The buna-N model operates at 160F max, the EPDM model at 300F max, and the Viton model at 250F max.

Ausco makes absolute pressure control valves, with several mounting types including line, manifold, rosan, cartridge, or custom type. These control valves operate with a fluid and ambient temperature range of -300F to 350F, pressure range from 0-10,000PSI (690 bar), a flow rate up to 40 gpm, and is constructed of corrosion resistant stainless steel, titanium, or aluminum.

Armstrong makes the Python 1100 series control valves in sizes from 1/2" to 2" NPT and an ANSI flange design from 2.5" to 4", and rated for a class IV shut off. These control valves feature a stream line flow path, top bush trims with guided plugs, top entry trim body and bolted bonnet.