Two valves, two positions, one shared logic: the spec is code-driven, not performance-driven. Discharge check valves prevent reverse-flow at the compressor and receiver inlet — the $100 part that protects the $25,000 air-end. ASME relief valves are mandatory on every pressurized vessel, written into OSHA 1910.169 and ASME Section VIII. This page walks both, position by position, with the cross-reference and code-citation flow that closes every receiver and every compressor quote.
Tap any type to jump to its page. The Decision Guide further down asks three questions that funnel the spec to one of these.
Discharge checks stop reverse flow at the compressor and receiver; ASME relief valves are the last-line release on every pressurized vessel.
ASME Section VIII, OSHA 1910.169, and the National Board set the selection criteria. This isn't a brand or a CFM comparison.
Reciprocating discharge runs 300–400°F and needs a hot-discharge check; every code vessel needs an ASME UV-stamped relief set at or below MAWP.
A reverse-rotation event destroys a rotary-screw air-end on shutdown. A general-service check on a recip discharge fails within months.
A lookalike valve fails inspection, voids insurance, and is a five-figure-per-violation OSHA citation. UV stamp + National Board, or it doesn't ship.
Conrader anchors compressor-service checks (hot-discharge to 450°F) and head relief; Kingston anchors receiver-mounted ASME relief from stock.
Distributor-facing reading. The trade-off column is the one that closes the loop — every type buys something and gives something up. Knowing what each type costs you is how the right one gets on the quote without a callback.
Reading the brand bench column — the bar shows how many of SPC's tier slots (Industry Leader · Emerging · Economical · adjacent) carry an option at that product type. A narrow bench here is by design: safety-side valves are code-driven, not tier-shoppable. Conrader anchors the compressor-service-grade check valves (with hot-discharge ratings to 450°F) and the small-body compressor-head relief valves; Kingston anchors the receiver-mounted ASME relief and discharge-line check valves at the sizes a fabrication or service shop quotes from stock. There is no economical tier in this category — non-ASME valves are not a legal substitute.
Draw a line from the customer's answer at the top to the type name at the bottom. This is the page distributors screenshot and send to a customer the day before a quote call — so the customer comes prepared with the answers, and the call is about the brand and the budget, not the basics.
Two rules behind the tree. Discharge checks are temperature-rated — match the rating to the compressor type (general-service for rotary-screw discharge, hot-discharge for reciprocating). Relief valves are code-certified — ASME UV stamp + National Board number on every quote, set pressure at or below vessel MAWP, relieving capacity at or above compressor full SCFM. The conversation here is "what does the code require and what does the position need," not "which brand performs better." On every receiver and every compressor service quote, both lines get checked.
Performance valves compete on dew point and CFM. Safety valves compete on UV stamps, National Board numbers, and temperature ratings. The code does the selling.
If the customer answers most of these at the first call, the second call is the quote. If they can't answer any, the system safety valves are rarely the only spec gap — flag it and push for a site walk.
The Control layer is what keeps a compressed air system running inside the band the rest of the plant was designed around — and what keeps it from ending up in the news when something goes wrong. Two jobs sit here: regulate the system so pressure, capacity, and oil temperature hold steady at the set point across changing load and ambient conditions, and protect the system so a single failure upstream cannot turn into a vessel rupture or reverse-rotation event downstream. The regulating side lives inside the compressor package — inlet, unloader, thermostatic and discharge-check valves running the load/unload, warm-up, and shutdown sequence on every cycle. The protective side lives on every pressurized vessel as code-mandatory ASME relief valves that respond to pressure alone, with no electrical signal and no operator action required. Get this layer wrong and the customer sees it everywhere — runaway electric bills from a compressor that won't unload, a hot oil sump destroying the air-end, a reverse-spin event at shutdown, an OSHA citation on an unprotected receiver. Get it right once and it disappears.
Three valves inside the rotary-screw package — capacity control (inlet), load/unload + startup (unloader), and oil-temperature regulation (thermostatic). Aftermarket cross-reference, keyed to the compressor nameplate.
→The system-level safeguards — discharge check valves preventing reverse flow at the compressor and receiver, plus ASME-mandatory relief valves on every pressurized vessel. Code-driven spec, not a tier choice.
Tell us the end-use, the rough flow, and what climate the unit would sit in. We'll come back with a configured quote — the right type, the right tier, and the upstream gear the warranty assumes.
—. We reply within one business day with pricing, lead-time, and configured parts.
