Swagelok CH Series High-Pressure Poppet Check Valve

Overview

The Swagelok CH Series is a family of high-pressure poppet check valves that allow flow in one direction and stop reverse flow in instrument, sampling and small-bore process lines. Machined from 316 stainless steel with a fluorocarbon FKM bonded poppet, the valves are rated up to 6000 psig (413 bar) at room temperature in the CH4 and CH8 sizes and up to 5000 psig (344 bar) in the CH16 size, depending on the end connection. Each valve is supplied with a fixed cracking pressure chosen at the time of ordering, from 1/3 psi up to 25 psi.

Seven Star LLC supplies Swagelok CH Series check valves to oil and gas producers, refineries, gas plants, chemical units, utilities and OEM skid builders in Oman and the GCC. We help customers choose the right size, end connection, cracking pressure and seal material, and we provide model selection support from Muscat.

How the Swagelok CH Series Check Valve Works

A spring holds the elastomer-bonded poppet against its seat. When the inlet pressure exceeds the outlet pressure by the cracking pressure, the poppet lifts and flow passes through the valve. When the differential falls, the spring returns the poppet and the valve reseals. Swagelok defines cracking pressure as the inlet pressure at which the first indication of flow occurs, a steady stream of bubbles, and reseal pressure as the pressure at which there is no indication of flow. The catalog also notes that a valve which has not been actuated for some time may show an initial cracking pressure higher than its set value.

The Swagelok CH Series body is made of an inlet body and an outlet body, sealed by a fluorocarbon FKM O-ring with a PTFE backup ring. A 316 stainless steel poppet stop limits poppet travel and a 302 stainless steel spring provides the closing force. Wetted parts are 316 stainless steel, FKM and PTFE-based lubricant, which suits most hydrocarbon, utility and instrument air services.

Sizes, Flow and Pressure Ratings

The Swagelok CH Series comes in three body sizes. The CH4 has a maximum flow coefficient (Cv) of 0.67, the CH8 a Cv of 1.8, and the CH16 a Cv of 4.7. End connections include fractional Swagelok tube fittings from 1/8 to 1 in., metric tube fittings from 6 to 25 mm, female and male NPT from 1/8 to 1 in., and female and male ISO threads. Ordering numbers follow the pattern SS-CHS4 for a 1/4 in. tube fitting body or SS-CHF8 for a 1/2 in. female NPT body, followed by the cracking pressure designator, for example SS-CHS4-1 for a 1 psi cracking pressure.

With fluorocarbon FKM seals, the CH4 and CH8 are rated 6000 psig (413 bar) from 10 to 100°F (−12 to 37°C), falling to 5160 psig (355 bar) at 200°F (93°C), 4660 psig (321 bar) at 300°F (148°C) and 4280 psig (294 bar) at 400°F (204°C). The CH16 is rated 5000 psig (344 bar) at room temperature and 3560 psig (245 bar) at 400°F (204°C). Some end connections carry a lower rating, so the final Swagelok CH Series pressure rating must be read from the dimensions table for the exact ordering number.

Cracking and Reseal Pressures

The Swagelok CH Series is offered with nominal cracking pressures of 1/3, 1, 5, 10 and 25 psi (0.03, 0.07, 0.35, 0.69 and 1.8 bar). For a 1/3 psi valve the cracking pressure range is up to 3 psi and it reseals at up to 6 psi back pressure; for 1 psi the range is up to 4 psi with reseal at up to 5 psi back pressure; for 5 psi the range is 3 to 9 psi with reseal at up to 2 psi back pressure; for 10 psi the range is 7 to 15 psi with reseal at 3 psi or more inlet pressure; and for 25 psi the range is 20 to 30 psi with reseal at 17 psi or more inlet pressure. Low cracking pressures suit gas sample return lines where pressure is limited, while higher settings help prevent unwanted flow from small upstream pressure fluctuations.

Seal Options and Sour Gas Version

Fluorocarbon FKM is the standard seal in stainless steel valves. Swagelok also lists Buna N, ethylene propylene and neoprene seals, selected by inserting a seal designator into the ordering number, and the FKM rating for the Swagelok CH Series is 10 to 400°F (−12 to 204°C). For hydrogen sulfide service, Swagelok offers a sour gas version of the CH series with materials selected in accordance with NACE MR0175/ISO 15156: alloy 400 body and poppet, ethylene propylene seals, PTFE backup ring and an alloy X-750 spring. The sour gas version is rated 5000 psig (344 bar), −50 to 300°F (−45 to 148°C), with 1/3, 1 and 5 psi cracking pressures and 1/4, 3/8 and 1/2 in. tube fitting ends.

Testing and Cleaning

Every Swagelok CH Series check valve is factory tested for crack and reseal performance. Fixed cracking pressure valves are cycled six times before testing, and seats have a maximum allowable leak rate of 1 std cm3/min of nitrogen. Valves with VCR or VCO end connections are processed to Swagelok Special Cleaning and Packaging (SC-11) to meet ASTM G93 Level C, and all other versions are cleaned to Swagelok Standard Cleaning and Packaging (SC-10).

Applications

• Preventing backflow with a Swagelok CH Series valve into analyzer sample conditioning systems and fast loops.
• Protecting chemical injection pumps and pressure sources from reverse flow.
• Purge gas, nitrogen and instrument air lines where one-way flow is needed.
• Hydraulic and high-pressure test stands up to the valve rating.
• Sour gas instrument tubing when the NACE version is specified.

The Swagelok CH Series valve is often installed alongside other Swagelok components on the same panel, such as 40G series one-piece ball valves for isolation, KPR series pressure regulators for pressure control, and Swagelok tube fittings for tubing connections.

Installation and Selection Notes (General Guidance)

These notes are general practice rather than manufacturer data. Install each Swagelok CH Series valve with the flow arrow in the direction of normal flow and support tubing so the valve body does not carry pipe loads. Choose a cracking pressure well below the normal operating differential so the valve opens fully, and remember that Swagelok states its check valves are designed for directional flow control only and must never be used as code safety relief devices. In pulsating or shock-loaded services, consider the effect on seat life and select seal materials compatible with the fluid and temperature.

Technical Specifications

How to Order

To order Swagelok CH Series check valves, send Seven Star LLC the fluid, maximum pressure and temperature, end connection size and type, required cracking pressure and seal material. Our engineers in Muscat will confirm the ordering number against the Swagelok catalog and prepare a formal quotation. The Swagelok CH Series catalog can be downloaded from this page, and we provide model selection support from Muscat for customers across Oman and the GCC.