Brand: Swagelok

Swagelok SS-4C2-1 Poppet Check Valve, 1/4 in. MNPT, 1 psig

Name: Swagelok SS-4C2-1 Check Valve 1/4 in. MNPT | Seven Star LLC
Brand: Swagelok
SKU: SS-4C2-1

Description

The Swagelok SS-4C2-1 is the male NPT form of the 1 psig poppet check valve. Both ends carry 1/4 in. tapered male threads, so it threads directly into female ports on tees, manifolds, regulators and instruments, saving two fittings and a joint. At 2.09 in. (53.1 mm) it is shorter than the female NPT SS-4C4-1 and the tube fitting SS-4C-1, and it is made from 316 stainless steel with an FKM O-ring and a 3000 psig (206 bar) rating.

Technical specifications

Parameter	Specification
Part number	SS-4C2-1
Description	Poppet check valve, fixed cracking pressure
Series	C
Body material	316 stainless steel
Connections	1/4 in. male NPT x 1/4 in. male NPT
Nominal cracking pressure	1 psig (0.07 bar)
Flow coefficient Cv	0.47
O-ring material	Fluorocarbon FKM
Working pressure	3000 psig (206 bar) at 100 F (37 C)
Length A	2.09 in. (53.1 mm)
Cleaning	Standard cleaning and packaging SC-10

Threaded in at both ends

A male-male check valve is compact because the threads, not nuts and ferrules, make the joint. Its length of 2.09 in. is the shortest of the 1/4 in. C series versions in the catalog. The price of that compactness is that the valve is fixed in position by thread engagement, so the flow arrow may end up facing the wrong way if you tighten it past the intended orientation; check the arrow before you finish tightening and use sealant rated for the fluid.

Do not use the body as a lever; hold it on the flats while you tighten into the port.

Low cracking pressure for protection

Placed ahead of a regulator, analyser or instrument, a 1 psig check valve prevents backflow while barely affecting normal flow. The catalog states nominal cracking pressure is the inlet pressure where the first steady stream of bubbles appears, and reseal pressure is where flow stops, and notes that valves not actuated for a while may crack at a slightly higher pressure at first. The fluorocarbon O-ring seals the poppet, so match it to the fluid.

The maximum Cv of 0.47 is the same as the other 1/4 in. 1 psig C series valves.

Comparing the 1/4 in. 1 psig family

SS-4C-1: tube fitting ends, 2.35 in. SS-4C4-1: female NPT, 2.15 in. SS-4C2-1: male NPT, 2.09 in. SS-4C1-1: male NPT by tube fitting. For other cracking pressures replace the final 1 with 1/3, 10 or 25, or use an adjustable CA valve. Provide the exact code and any non-standard O-ring when requesting a quotation.

This is a directional flow-control device and not a safety relief device or a tight block valve.

Documents and quotation

For the full data, download the Swagelok check valves C, CA, CH, CP and CPA series catalog MS-01-176 (EN, rev. N) attached here. Quotation requests for SS-4C2-1 are matched to the exact model or order code, so include the quantity and any option or certification. We are an independent supplier based in Muscat.

Check the code, size and end connection against the attached document before purchase, since variants with similar numbers exist. Related items: product category.

Datasheets & Documents

Catalog Swagelok check valves C, CA, CH, CP and CPA series catalog MS-01-176 (EN, rev. N) Download

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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.

FAQ

Questions about the Swagelok SS-4C2-1 Poppet Check Valve, 1/4 in. MNPT,

Answers from our engineering team on installation, compatibility and integration.

01What ports does SS-4C2-1 have?

1/4 in. male NPT at both ends.

02What is its cracking pressure?

Nominal 1 psig (0.07 bar).

03How long is it?

2.09 in. (53.1 mm) per the catalog.

04What is the rating?

3000 psig (206 bar) at 100 F (37 C).

05Which O-ring is used?

Fluorocarbon FKM as standard.