Swagelok 3/8" Check Valve SS-CHS6-25, Poppet, 25 psi Cracking
ABOUT THIS PART
Genuine Swagelok SS-CHS6-25 poppet check valve, 3/8 inch Swagelok tube fitting both ends, 316 stainless, 25 psig (1.8 bar) cracking pressure. This is the 25 psi valve, not the 1 psi one, and the two are not interchangeable. $74.95.
Clearance, down from $145.00. These are unused, off our own shelf, and there is no reorder behind them. Priced below every listing we could find in October 2026, where the lowest asking prices on this part number were $83.00 and $95.00 for unused stock, $125.00 new, $164.30 new with a 30 to 45 day lead time, and $150.00 for a used one.
Specifications, as Swagelok publishes them
| Part number | SS-CHS6-25 |
| Swagelok description | Stainless steel poppet 6000 psig (413 bar) check valve, 3/8 in. Swagelok tube fitting, 25 psig (1.8 bar) |
| Series | CH, the 6000 psig (413 bar) poppet check valve series |
| Cracking pressure | 25 psig (1.8 bar) nominal, fixed |
| Cracking pressure range | 20 to 30 psi (1.4 to 2.1 bar), which is Swagelok's own published spread on the 25 psi spring |
| Reseal | 17 psi (1.2 bar) or more inlet pressure |
| Room temperature pressure rating | 6,000 psig at 100 F (413 bar at 37 C) |
| Pressure rating at temperature | 4,280 psig at 400 F (294 bar at 204 C) |
| Cv, maximum | 1.8 |
| Connections | 3/8 in. Swagelok tube fitting, both ends |
| Body material | 316 stainless steel, ASTM A479 |
| Poppet | Fluorocarbon FKM bonded elastomer on A479 stainless |
| Spring | 302 stainless steel, ASTM A313 |
| Seal and O-rings | Fluorocarbon FKM |
| Backup ring | PTFE, ASTM D1710 |
| Lubricant | Christo-lube MCG 111 (WL8) |
| Cleaning | Standard cleaning and packaging, SC-10 |
| Price | $74.95, down from $145.00 |
Temperature, and the honest version of it
- 3P Certz engineering reports ECR-190105-R0 and ECR-190082-R3 list the CHS6 poppet check valve at -50 F to 300 F (-46 C to 149 C) on an N.B. Oler build. That is the figure we publish.
- The part number 3P Certz qualified in those reports is SS-CHS6-100, the 100 psig (6.9 bar) cracking version of this same CHS6 series valve. Same body, same seals, different spring. We say so rather than implying the 25 psi version was the one reviewed.
- Swagelok publishes a pressure rating point at 400 F (204 C), so the valve itself goes higher. We quote the lower number because it is the one that was reviewed for service on our equipment.
- 100 F (37 C) is the reference temperature for the 6,000 psig (413 bar) rating. It is not a maximum operating temperature, and a page that says so is wrong.
Cracking pressure, and why 25 psi
- 25 psig (1.8 bar) is a mid-range set point. It holds shut against a modest back pressure and still opens well below system pressure.
- Swagelok publish this series at 1/3, 1, 5, 10 and 25 psi (0.03, 0.07, 0.35, 0.69 and 1.8 bar). A 1 psi valve in a 25 psi position will chatter and pass; a 100 psi valve in a 25 psi position will not open when you want it to. Read the number on the part, not the picture.
- Swagelok also publish a cracking range rather than a single figure. On the 25 psi spring it is 20 to 30 psi (1.4 to 2.1 bar), and a valve that has sat unused for a while may crack higher than its set point the first time. That is normal and Swagelok say so.
- If you want 1 psi (0.07 bar) or 100 psi (6.9 bar) cracking in the same 3/8 inch size, we have the Superlok SHCV2-S-6 in both set points at $59.95.
- Not sure which set point your line needs? Call 541-330-6409 during shop hours.
Fitment
- Fits 3/8 inch OD tube, Swagelok tube fitting both ends. Directional, so it has to be installed with the flow.
- Does not fit tri-clamp, NPT or hose ends, and it is not a relief valve. Swagelok's own caution is that a check valve is a directional flow control device and must never be used as a code safety relief device. We repeat it because people try.
- Tube and spare nut and ferrule sets are separate items.
- Do not mix Swagelok two-ferrule components with another manufacturer's. That is Swagelok's own caution and we follow it.
$74.95, priced on this page. Clearance, unused stock. Ships from Bend, Oregon.
SPECIFICATIONS
▦ IN YOUR MANUAL
This part appears in the operator manual that ships with your system. The QR code there links to this page.
◈ REFERENCE FOR THIS PART
COMMON QUESTIONS
Is this the 25 psi or the 1 psi version?
The 25 psi. Cracking pressure is 25 psig (1.8 bar), and it is fixed. Swagelok publish this series at 1/3, 1, 5, 10 and 25 psi, so check the number on the part you are replacing.
Is this a clearance item?
Yes. These are unused, off our own shelf, down from $145.00, and there is no reorder behind them.
What happens if I fit the wrong cracking pressure?
A set point that is too low will chatter and pass. A set point that is too high will not open when you want it to. Match the number, not the picture.
Does it crack at exactly 25 psi?
No, and Swagelok do not claim it does. The published range on the 25 psi spring is 20 to 30 psi (1.4 to 2.1 bar), and it reseals at 17 psi (1.2 bar) or more inlet pressure. A valve that has sat unused for a while may crack higher the first time.
What is the maximum working pressure?
6,000 psig at 100 F (413 bar at 37 C), and 4,280 psig at 400 F (294 bar at 204 C). 100 F (37 C) is the reference temperature for the 6,000 psig figure, not a temperature limit.
What temperature range do you publish?
-50 F to 300 F (-46 C to 149 C). That is the figure 3P Certz lists for the CHS6 poppet check valve in engineering reports ECR-190105-R0 and ECR-190082-R3. The part number qualified in those reports is SS-CHS6-100, the 100 psig (6.9 bar) cracking version of the same series valve, so the body and seals are the same and the spring is not. Swagelok publishes a rating point at 400 F (204 C), so the valve goes higher, but we quote the reviewed number.
What is the Cv?
1.8 maximum.
What is it made of?
316 stainless body to ASTM A479, an FKM bonded elastomer poppet, a 302 stainless spring to ASTM A313, fluorocarbon FKM O-rings, a PTFE backup ring to ASTM D1710, and Christo-lube MCG 111 lubricant.
Is it genuine Swagelok?
Yes. Part number SS-CHS6-25.
Does it matter which way round I fit it?
Yes. It is a one-way valve. Fit it with the flow.
Is this a relief valve?
No. A check valve stops reverse flow. A relief valve protects against overpressure. Swagelok's own instruction is that a check valve must never be used as a code safety relief device.
Is there a cheaper option in 3/8 inch?
The Superlok SHCV2-S-6 at $59.95, available here at 1 psi (0.07 bar) or 100 psi (6.9 bar) cracking rather than 25 psig (1.8 bar), so it is only an option if your line suits one of those set points.
What does it cost?
$74.95, down from $145.00, priced on this page.