Brand: Swagelok

Swagelok SS-4CPA4-3 Adjustable Poppet Check Valve, 1/4 in. FNPT

Name: Swagelok SS-4CPA4-3 Adjustable Check Valve | Seven Star LLC
Brand: Swagelok
SKU: SS-4CPA4-3

Description

The Swagelok SS-4CPA4-3 is a one-piece poppet check valve whose cracking pressure can be set in the field. The CPA series carries an adjusting screw, and the -3 version covers the 3 to 50 psig (0.21 to 3.5 bar) band, so one part number replaces several fixed-pressure valves when a back-pressure, pressure-hold or sample-vent setting needs to be tuned on site. It has 1/4 in. female NPT ends and a 316 stainless steel body.

Technical specifications

Parameter	Specification
Part number	SS-4CPA4-3
Description	1-piece poppet check valve, adjustable cracking pressure
Series	4CPA
Body material	316 stainless steel
Connections	1/4 in. female NPT x 1/4 in. female NPT
Cracking pressure range	3 to 50 psig (0.21 to 3.5 bar)
Flow coefficient Cv	0.35
O-ring	Fluorocarbon FKM
Working pressure	3000 psig (206 bar) at 100 F (37 C)
Overall length A	2.98 in. (75.7 mm)
Hex D	3/4 in.
Lubricant	PTFE-based (4CPA series)
Testing / finish	No optional testing / standard

Adjustable cracking pressure

The CPA series uses the same one-piece body as the CP series but adds a spring-adjusting screw. The catalog lists four adjustment bands: 3 to 50 psig (the -3 designator, as in this part), 50 to 150 psig, 150 to 350 psig and 350 to 600 psig. The valve is set at a stated pressure at the factory and can be changed by turning the adjusting screw; recheck the setting with a gauge after adjustment, because the catalog notes that cracking and reseal pressures can vary slightly.

Adjustable check valves are used as back-pressure valves on sample vents, as pressure-hold devices in analyser loops and wherever an unequal inlet and outlet pressure has to be maintained at a defined value.

Technical data in brief

Maximum Cv is 0.35 for the 4CPA, matching the fixed-pressure CP valves, and the working pressure is 3000 psig (206 bar) for 316 stainless steel with FKM O-rings. Temperature derating is the same as for the other CP and CPA valves: 2575 psig at 200 F and 2185 psig at 375 F. At 2.98 in. overall and with a 3/4 in. hex, the adjustable body is longer than the 1.62 in. fixed-pressure SS-4CP2-1 because it holds the adjustment spring and screw. The CPA valves use a PTFE-based lubricant.

Flow curves for the 4CPA series are in the catalog for air and water at set pressures, which helps when you need the pressure drop at a given flow.

Ordering and use

SS-4CPA4-3 reads stainless steel, 4CPA series, female NPT (4) and cracking range 3 to 50 psig (-3). Change the final designator to -50 for 50 to 150 psig, -150 for 150 to 350 psig or -350 for 350 to 600 psig as listed in the catalog family, and the end digit for male NPT (2) or male by female (5). Brass versions use B instead of SS.

Install with the flow arrow correct and a filter upstream. The catalog states that Swagelok check valves are for directional flow control only and must never be used as code safety relief devices, and they are not bubble-tight isolation devices. Confirm the setting with a pressure gauge after installation and lock the adjustment according to the catalog instructions.

Documents and quotation

This page links the official Swagelok check valves C, CA, CH, CP and CPA series catalog MS-01-176 (EN, rev. N), which holds the ordering tables, ratings and materials behind the figures above. Seven Star LLC is an independent supplier in Muscat; for a quotation on SS-4CPA4-3, tell us the quantity and any option you need, such as handle, packing or special cleaning.

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About brand

Swagelok is the American maker of tube fittings and small-bore valves, best known for its two-ferrule compression tube fitting. Fred A. Lennon and Cullen B. Crawford founded it in Cleveland, Ohio, in July 1947 as Crawford Fitting Company to make that fitting. Lennon bought the whole business and the patent in 1948, and the company has been based in Solon, Ohio, since the mid-1960s.

Seven Star LLC is an independent supplier in Muscat. We list Swagelok tube fittings, needle, ball, check, relief and metering valves, filters, regulators and sample cylinders, and supply them for instrument tubing and analyser systems in Oman and the GCC by exact part number.

Swagelok company profile

Established	July 1947, Cleveland, Ohio, as Crawford Fitting Company
Founders	Fred A. Lennon and Cullen B. Crawford; Lennon bought out Crawford in 1948
Headquarters	Solon, Ohio, since the mid-1960s
Product families	Tube fittings and adapters, face seal fittings, needle, ball, plug, check, relief and diaphragm valves, filters, regulators, quick-connects, sample cylinders and hoses

Milestones

1947: Fred A. Lennon and Cullen B. Crawford found Crawford Fitting Company in Cleveland in July.
1948: Lennon buys out Crawford.
Mid-1960s: Headquarters move to Solon, Ohio.

Swagelok products we list

Family	Models	Typical use
Tube fittings	Overview, SS-810-6 union, SS-810-3 tee, SS-810-9 elbow, SS-810-4 cross, SS-810-1-8 male connector, SS-810-7-8 female connector, SS-810-61 bulkhead, SS-12M0-6 metric union, VCR face seal	Leak-tight connections on instrument and process tubing
Needle and metering valves	SS-1RS4, SS-1RF4, SS-18RF6, SS-6NBS6, SS-20VS4, SS-4MG	Isolation and fine flow adjustment on instrument lines and sample systems
Ball and plug valves	40G, 40GX 3-way, 60 Series, 83 Series, P4T plug	Quick quarter-turn shut-off and switching
Check, relief and sealed valves	SS-4C-1, CH, R3A, RL3, SS-4BK bellows, SS-DLS4 diaphragm	Backflow prevention, overpressure relief and leak-free sealing for toxic or high-purity media
Filters, regulators, sampling	SS-4F-2, SS-4TF-7, KPR regulator, sample cylinders, QC quick-connects	Analyser sample conditioning and gas or liquid sampling

A Swagelok part number can be read directly. In SS-810-6, "SS" is 316 stainless steel, "810" means a 1/2 in. tube fitting (8 sixteenths of an inch, 10 series), and "-6" is a union. A suffix such as "-8" adds a 1/2 in. NPT end, and "M0" marks metric tube, as in SS-12M0-6 for 12 mm. Tube fittings must be made up the same way every time: finger-tight, then 1 1/4 turns for most sizes. A gap inspection gauge confirms the fitting has been pulled up.

Where Swagelok products are used

In Oman and the GCC, Swagelok fittings and valves are used on instrument impulse lines, analyser sample systems, hydraulic and pneumatic control tubing, chemical injection and gas sampling in oil and gas, refining, petrochemical, power and laboratory installations.

Ordering Swagelok products: what we need

Send the full Swagelok part number (for example SS-810-6 or SS-1RS4), the material, and the tube size in inches or millimetres. For valves, add the end connections and any options. For sample cylinders, add the volume, pressure rating and end configuration.

Facts checked against Swagelok company history, October 2026.

Browse Swagelok products by category: Pipes & Fittings, Regulators, Fittings & Valves.