Conrader unloader valves (D / DL series), inlet control valves, check valves, safety relief valves, and piloted unloader-check combination valves
Coverage Covers the control- and safety-valve variants taught on the Product Type page: unloader valves (D 20 SCFM / DL 60 SCFM), inlet control valves, discharge check valves, safety relief valves, and combination unloader-check units — selected by symptom and matched by port size and pressure rating to the OEM compressor.
Conrader Compressor Controls is a family-owned American manufacturer (Erie, PA) building compressor control and safety valves since 1925, with 100% US manufacture. The unloader line runs the D series (20 SCFM; 1/4" or 3/8" tube or FNPT inlet) and DL series (60 SCFM; 1/2" FNPT inlet), both rated 20-250 PSI operating pressure over a -15°F to 400°F temperature range. Conrader also makes inline check valves, ASME-style safety relief valves for over-pressure protection, and all-in-one piloted unloader-check combination valves for continuous-run service. Replacement valves are matched to the compressor by Conrader's OEM cross-reference by make / model / HP.
Why Conrader here Conrader is the dedicated compressor control- and safety-valve specialist — a 1925-founded, fully US-made manufacturer with an OEM cross-reference library covering compressor service valves. It gives the DC channel one authoritative source for the mechanical, failure-driven side of compressor MRO that filtration brands do not cover, completing the annual service kit with the valve inspection.
Conrader compressor-service check valves; N-Series piloted unloader/check combination units
Coverage Standalone discharge check valves and N-Series piloted unloader/check combination units (e.g. NDC, NSDC, NLDC electric-motor series, 20–60 SCFM; NSG, NLG, NG gas-engine series). Connection types include compression tube, SAE 45° flare, and male/female NPT/BSPT depending on series.
Conrader's discharge check valves are purpose-built for compressor service — they sit on the discharge line and block compressed air from flowing backward into the pump head when the compressor stops. They share the line's 20–250 PSI operating range and -15°F to 400°F temperature range, which covers hot compressor-discharge service. Conrader builds both the standalone check valve and the N-Series combination unit, where the check valve, pilot, and unloader are packaged together; the combination unit reduces a multi-component control circuit to a single install point. Selection is by compressor make / model / HP cross-reference and by matching the discharge-port NPT size. Per the Controls and Components 2026 Catalog (p.76-79), the Conrader in-tank check valve range covers CTLB one-piece in-tank valves and CT/CTL-series two-piece in-tank valves, 1/4"–1 1/2" NPT, 15–150 CFM, 500 PSI max, -65°F to 450°F, with a 1/8" unloader port, cross-referenced to CDI numbers; all-brass serviceable construction with 302 stainless spring and reinforced PTFE seal, male outlet for tanks/receivers, made in USA.
Why Conrader here Conrader engineers its check valves specifically for compressor-discharge conditions — hot air, pulsation, and backflow load — and the -15°F to 400°F rating suits hot discharge service. With a published OEM cross-reference and a combination unloader/check option, a DC rep can replace a leaking check valve, or consolidate an aging control circuit into one combination unit, for nearly any installed compressor. US-made in Jamestown, NY.
Conrader inlet / capacity-control valves
Coverage Inlet throttle / capacity-control valves for rotary screw and large reciprocating compressors. Solenoid-driven and mechanically actuated inlet-valve configurations both covered; the correct configuration is matched to the specific compressor model. Small reciprocating compressors are served by unloader and check valves rather than an inlet valve.
Conrader's inlet control valves are the capacity-control element for rotary screw and large reciprocating compressors — the valve throttles intake air, opening under load and closing when the machine unloads. Conrader builds these in Jamestown, NY, to compressor-service grade, and selection runs through the same make / model / HP cross-reference Conrader publishes for its other compressor controls. Inlet-valve configuration is more compressor-specific than an unloader or check valve, and many installations pair the valve with a control solenoid — Conrader's technical support can confirm the solenoid-driven vs. mechanical configuration for a given model.
Why Conrader here Conrader specializes in compressor capacity control, and its published OEM cross-reference plus factory technical support let a DC rep match an inlet valve for a rotary screw compressor that was never sold by SPC — the machine is already in the field and the inlet valve is a wear item. US-made in Jamestown, NY, with engineering depth on the more configuration-sensitive end of the compressor-control range.
CMP series minimum pressure / check valves
Coverage 3/4"–3" NPT, 100–750+ CFM, 50–70 PSI cracking pressure
Installed downstream of the air-oil separator on rotary screw compressors; maintains minimum sump pressure for lubrication and protects the separator element. Sizing is OEM-spec dependent.
RCB-HU / RCBM-HU manual hand-unloader pilot valves
Coverage Stocked PSI ranges from 75–95 up to 140–175, 1/8"/1/4" FNPT ports
Manual hand-unloader pilot valves for compressor unloading control, stocked across many pressure ranges.
SRH-Series hard-seat safety valves; SRV-Series soft-seat safety valves
Coverage Hard-seat (SRH-Series, 25–350 PSI) and soft-seat (SRV-Series, 25–450 PSI) compressor-service safety valves in 1/8 in / 1/4 in / 3/8 in connections; brass body. Covers compressor-head and discharge-side relief. Larger receiver-port relief connections (typically 1/2 in–1 in NPT and above) sit outside this connection range.
Conrader's safety-valve line is purpose-built for compressor-head and discharge-side over-pressure protection. The SRH-Series is the hard-seat (metal-to-metal seal) valve, rated 25–350 PSI; the SRV-Series is the soft-seat (elastomer seal) valve, rated 25–450 PSI. Both come in 1/8 in, 1/4 in, and 3/8 in connection sizes — the compressor-discharge port range — with common factory set pressures of 125, 150, and 200 PSI. Conrader certifies the line under its ISO 9001 system to ASME Boiler and Pressure Vessel Code Section VIII Division 1 and registers it for use in Canada (CRN). Selection follows Conrader's compressor make / model / HP cross-reference. Per the Controls and Components 2026 Catalog (p.84-89), the Conrader SRV soft-seat safety relief valve range is stocked at 25–60+ PSI set points with 187–765 CFM flow ratings for air receivers and compressed air systems.
Why Conrader here Conrader is the compressor-control specialist in this category, so its safety valve drops directly into a compressor-service conversation alongside the unloader, check, and inlet valves — one brand, one cross-reference, for the whole compressor control set. The SRH/SRV connection range (1/8 in–3/8 in) and 25–450 PSI span match compressor-head and discharge-port protection, and ASME Section VIII Division 1 certification keeps it code-legal on the unfired pressure points it protects. US-made in Jamestown, NY.
Cable-style throttle controls (TCP/TCLP/TCLPW/TCXLPW, TCI/TCLI), pilot unloader check valves
Coverage -15°F to 400°F, 500 PSI max, engine-HP-rated, varied stroke lengths and actuation PSI
Controls engine speed of gas/diesel engine-driven compressors via cable to throttle arm; made in USA. Section also covers pilot unloader check valves.
D Series / DL Series unloader valves; N-Series piloted unloader and combination unloader/check units
Coverage Standalone signal-actuated unloader (D Series 20 SCFM, DL Series 60 SCFM); piloted unloader and combination unloader/check units (N-Series, factory-set pilot ranges such as 110–135 PSI and 120–150 PSI, field-adjustable). Reciprocating and continuous-run configurations both covered. Pilot-valve circuits available where the control scheme calls for one.
Conrader builds compressor control valves in Jamestown, NY. The unloader line covers both the standalone signal-actuated unloader and the piloted combination unit. The D Series is the small-flow body — 1/4 in or 3/8 in inlet, rated to 20 SCFM; the DL Series is the larger body — 1/2 in inlet, rated to 60 SCFM. Both run a 20–250 PSI operating range and a -15°F to 400°F temperature range. Conrader also offers the N-Series piloted unloader/check combination, which packages the check valve, pilot, and unloader in one device for a single-point install. Selection is by compressor make / model / HP cross-referenced to the OEM part number.
Why Conrader here Conrader is a dedicated compressor-control specialist with a published OEM cross-reference library, so a DC rep can read a compressor nameplate in the field and match the equivalent unloader without a factory order. US-made in Jamestown, NY, with standalone and combination-unit options on one catalog — the unloader is a recurring, non-discretionary service part, and Conrader makes it sourceable for nearly any compressor brand already installed at a customer site.
