Brand: Swagelok

Swagelok SS-R4S8 Proportional Relief Valve, 1/2 in. Tube

Name: Swagelok SS-R4S8 Proportional Relief Valve | Seven Star LLC
Brand: Swagelok
SKU: SS-R4S8

Description

The Swagelok SS-R4S8 is the larger-bore proportional relief valve in the R series: 1/2 in. Swagelok tube fitting ends, a 0.250 in. (6.4 mm) fully open orifice and set pressures from 50 to 1500 psig (3.4 to 103 bar). Where the R3A valves give a small flow at up to 6000 psig, the R4 passes more fluid at moderate pressure, so it suits pump discharge protection, pilot plant piping and sample conditioning with 1/2 in. tubing.

Technical specifications

Parameter	Specification
Part number	SS-R4S8
Description	High-pressure (R4) proportional relief valve, no handle
Series	R4
Body material	316 stainless steel
Connections	1/2 in. Swagelok tube fitting inlet and outlet
Fully open orifice	0.25 in. (6.4 mm)
Set pressure range	50 to 1500 psig (3.4 to 103 bar), by spring selection
Outlet working pressure	2500 psig (172 bar)
Seal material	Fluorocarbon FKM
Height / width	About 5.92 in. (150 mm) / 1.83 in. (46.5 mm), per catalog
Set pressure repeatability	+/- 3 psig (0.20 bar) or +/- 5 percent, whichever is greater, at 60 to 80 F
Cleaning	Standard cleaning and packaging SC-10

Higher flow, moderate pressure

The R4 and R3A are the two high-pressure designs in the catalog. The R4 uses 1/2 in. or 12 mm ends and a 0.25 in. orifice, but its set pressure range is 50 to 1500 psig instead of up to 6000 psig. High-pressure valves in this series minimise the effect of system back pressure by design, and a quad seal stops leakage around the stem during relief.

Valves are available factory-set to a specified pressure, or you can install the spring that covers the range you need and fit its label.

Not a safety valve

Like all R series valves, the R4 is a proportional relief valve: it opens gradually as pressure rises above the set value and does not carry a rated capacity at a given accumulation. The catalog says plainly that these valves are not certified to ASME or other codes, must not be used as ASME Boiler and Pressure Vessel Code safety relief devices and are not safety accessories under the Pressure Equipment Directive 2014/68/EU. The system designer must decide when a code-stamped device is needed.

Each valve is tested for set and resealing performance before it ships.

Ordering notes

SS is 316 stainless steel, R4 the series, S the Swagelok tube fitting end and 8 the 1/2 in. size. The 12 mm version is SS-R4S12MM, and SS-R4M8S8 has a male NPT inlet. For low pressures up to 225 psig, the RL4 series (such as SS-RL4S8) with a single spring is the better match. Provide set pressure, fluid and temperature when requesting a quotation.

Maximum set pressure drops with temperature and seal material, so check the table in the catalog for hot service.

Documents and quotation

The attached Swagelok proportional relief valves R series catalog MS-01-141 (EN) is the reference for every value on this page. Seven Star LLC, an independent supplier in Muscat, quotes SS-R4S8 against the exact code; please add the quantity and any special requirement.

Verify the model, rating and connection against your specification and the attached document before ordering. Related items: product category.

Datasheets & Documents

Catalog Swagelok proportional relief valves R series catalog MS-01-141 (EN) 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-R4S8 Proportional Relief Valve, 1/2 in.

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

01What does SS-R4S8 protect?

Pumps, piping and instruments at up to 1500 psig set pressure, with a gradual (proportional) opening.

02What size are the connections?

1/2 in. Swagelok tube fitting at both ends.

03Is it ASME certified?

No. The catalog says it is not a code safety relief device.

04What is the orifice size?

0.25 in. (6.4 mm) fully open.

05How do I set it?

Select the spring for the range and apply the matching label, or order it factory-set.