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Brand: Swagelok
Swagelok SS-RL3S4 Low-Pressure Proportional Relief Valve
Description
Proportional overpressure relief for low-pressure instrument systems
The Swagelok SS-RL3S4 is a low-pressure proportional relief valve from the Swagelok R series, with a 316 stainless steel body and 1/4 in. Swagelok tube fitting inlet and outlet. It opens gradually as system pressure rises above the set point and recloses once pressure falls, which makes it suitable for protecting analyzer sample systems, instrument gas supplies, purge lines and small liquid circuits that run below 225 psig.
Unlike the high-pressure R3A and R4 valves, which need a spring kit selected for the set range, the RL3 ships with one spring that covers the full 10 to 225 psig range. The set pressure is adjusted with the cap and secured with a lock nut and lock wire.
Technical specifications
Data from Swagelok catalog MS-01-141 (Rev S, October 2021), Proportional Relief Valves, R Series.
| Parameter | Specification |
|---|---|
| Ordering number | SS-RL3S4 |
| Series | RL3, low pressure |
| End connections | 1/4 in. Swagelok tube fitting inlet and outlet |
| Fully open orifice | 0.19 in. (4.8 mm) |
| Set pressure range | 10 to 225 psig (0.7 to 15.5 bar), single spring |
| Inlet working pressure | 300 psig (20.6 bar) |
| Outlet working pressure | 225 psig (15.5 bar); outlet must not exceed inlet |
| Set pressure repeatability | ±3.0 psig or ±5% (greater value) at 60 to 80°F; ±6.0 psig or ±20% outside that range |
| Minimum resealing pressure | 50% of set at 10 to 20 psig; 91% of set at 175 to 225 psig |
| Wetted materials | 316 SS body (A182), stem, seat and insert; 302 SS plug; FKM O-rings, PTFE-coated FKM quad seal |
| Spring | S17700 SS |
| Cleaning | SC-10 standard; SC-11 option |
| Code status | Not ASME certified; not a PED 2014/68/EU safety accessory |
Related ordering numbers
| Ordering number | End connections |
|---|---|
| SS-RL3S6MM / SS-RL3S8MM | 6 mm / 8 mm Swagelok tube fittings |
| SS-RL3M4-S4 | 1/4 in. male NPT inlet, tube fitting outlet |
| SS-RL3M4-F4 | 1/4 in. male NPT inlet, female NPT outlet |
| SS-RL3M4F4-RT | 1/4 in. male ISO inlet, female ISO outlet |
| SS-RL4S8 / SS-RL4S12MM | RL4 series, 1/2 in. / 12 mm tube fittings, 0.25 in. orifice |
| 177-13K-RL3 | Replacement spring kit, 10 to 225 psig |
| SS-3K-RL3- | Seal kit basic number (add seal designator) |
Setting and application notes
Because this is a proportional design, it has no rated capacity at a given accumulation, and Swagelok states it must not be used as an ASME Boiler and Pressure Vessel Code safety relief device. Where a code-stamped device is required, the system designer has to specify one. Back pressure on the outlet raises the effective set point: to compensate, multiply the expected back pressure by 0.8 and subtract the result from the target set pressure, then preset the valve with the outlet at atmosphere. A valve that has been idle for a long time may first open above its set pressure. Add -SET to receive a valve set, tested, locked and tagged to a specified pressure with a test certificate.
Documents and quotation
The attached Swagelok R series catalog includes flow curves, dimensions, spring and seal kit tables. For a quotation, state the ordering number, required set pressure if factory setting is wanted, seal material and quantity. More relief devices are listed under Safety Relief Valves.
Datasheets & Documents
- Catalog Swagelok Proportional Relief Valves R Series catalog (MS-01-141, Rev S, 10/2021) Download
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About brand
Two-ferrule tube fittings made Swagelok a familiar name on instrument air headers, impulse lines and analyzer sample systems. The company has made fluid system components since 1947 and is based in Solon, USA. Seven Star LLC sources and supplies Swagelok tube fittings, ball valves, needle valves, quick-connects, face seal fittings and pressure regulators for plants in Oman, checking every ordering number against the manufacturer's catalog before an offer is made.
Swagelok product families listed here
The items on this page cover the small-bore components an instrument technician handles most often. Swagelok tube fittings join metric and fractional tubing without threading or welding. Swagelok ball valves are represented by the 40 series, the 40G series one-piece instrumentation ball valve (for example SS-43GS4) and the three-way pattern listed as 40GX. The SS-1RS4 is an integral bonnet needle valve from the 1 series. VCR metal gasket face seal fittings serve high-purity and vacuum lines, QC series quick-connects are used where lines are coupled and uncoupled often, and the KPR series is a pressure-reducing regulator.
Where Swagelok components are used
Typical duties are transmitter hook-ups, manifolds and impulse tubing, analyzer shelters and sample conditioning panels, chemical injection skids, gas cylinder panels in laboratories, and test benches. In oil and gas service across the GCC, the usual questions are material grade, pressure rating at temperature and, for sour service, whether the manufacturer offers the item to NACE MR0175 requirements.
Ordering Swagelok fittings and valves: what we need
A Swagelok ordering number carries most of the specification. In SS-43GS4, SS is 316 stainless steel, 43G identifies the valve series and size, and S4 is a 1/4 in. Swagelok tube fitting end connection. Send the complete ordering number including any suffix for handle, seat or cleaning option. If you do not have it, give us the tube outside diameter and wall thickness, body material, end connections on each port, working pressure and temperature, and the fluid. For a KPR regulator we also need inlet pressure, the outlet control range and the port configuration.
Browse Swagelok products by category: Pipes & Fittings, Regulators, Fittings & Valves.
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Frequently Asked Questions
What set pressure range does the SS-RL3S4 cover?
The RL3 series has one installed spring covering 10 to 225 psig (0.7 to 15.5 bar). Valves can be ordered factory-set by adding -SET.
Is the SS-RL3S4 a code safety valve?
No. Swagelok states R series proportional relief valves are not certified to ASME or other codes and are not PED safety accessories.
What is the maximum inlet pressure of the RL3 series?
Inlet working pressure is 300 psig (20.6 bar) and outlet working pressure 225 psig (15.5 bar).
How does back pressure affect the RL3?
Back pressure raises the set pressure. Swagelok advises multiplying back pressure by 0.8 and subtracting it from the desired set pressure when presetting.
Which seal materials are available?
FKM is standard. Buna N (-BU), ethylene propylene (-EP) and neoprene (-NE) are ordered by adding the designator to the ordering number.
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