FITOK CHSS-NS4-2 Poppet Check Valve, 1/4 in. Male NPT

CHSS-NS4-2 is a FITOK CH Series poppet check valve in 316 stainless steel with 1/4 in. male NPT ends and an FKM O-ring. The product page lists 6,000 psig (414 bar), Cv 0.67 and a nominal cracking pressure of 1 psig (0.07 bar), selected by the code -2.

A spring-loaded check valve for small lines

A poppet check valve holds a spring-loaded poppet against a seat. Flow in the intended direction lifts the poppet once the pressure difference passes the cracking pressure; reverse flow pushes the poppet harder onto the seat and the O-ring seals. This design takes little space and can be fitted in any orientation when the spring is used, which is useful in instrument and sampling lines.

The code splits into CH for the series, SS for 316 stainless steel, NS4 for a 1/4 in. male NPT connection and -2 for the cracking pressure option of 1 psig. The overall length is 2.17 in. (55.1 mm) and the hex is 11/16 in. (17.5 mm).

Features

• Spring-loaded poppet with FKM O-ring seal.
• Working pressure up to 6,000 psig (414 bar).
• Cv 0.67 for forward flow.
• Nominal cracking pressure of 1 psig with the -2 option; higher values are offered by other spring codes.

Technical specification

Specification of CHSS-NS4-2

Cracking pressure, seal material and connection

The cracking pressure is the pressure difference needed to open the valve. For gravity-independent operation in gas lines, 1 psig is a light spring that opens easily. A heavier spring gives a firmer closing force against back flow but costs pressure drop in the forward direction, so choose it to suit available supply pressure.

The FKM O-ring suits many hydrocarbons and mineral oils but has limits with some solvents, amines and hot water or steam. Verify compatibility with the process fluid, and ask about other elastomers if needed.

Temperature note: the catalog feature text and the product page show different lower limits, 10 F (-12 C) in the text and -10 F (-23 C) on the page. Confirm the value with the manufacturer if your service is near the lower limit.

Fitting notes

Install the valve with the arrow on the body pointing in the flow direction. The male NPT ends need a thread sealant suitable for the fluid, applied to the thread only.

Do not use a check valve as the only barrier for isolation. It is meant to prevent back flow but may weep slightly at low differential pressure, especially with fine debris on the seat. A filter upstream extends service life.

A check valve is passive, so it needs no power or signals, which is why it is common on remote skids. If the line carries pulsating flow, the poppet can chatter; in that case choose a heavier spring or fit a damper upstream. Keep a record of the cracking pressure code in the plant spares list, because the spring option cannot be seen from the outside of the valve.

GCC applications

General engineering note: small check valves are used at chemical injection quills, on pump discharge instrument lines, in compressed air and nitrogen headers, and on sampling systems at refineries, gas plants and power stations. They help protect regulators and instruments from reverse pressure. Confirm certification and material requirements in the project specification.

Related FITOK items

The same catalog lists CV, CO, CA, COA and CL series check valves with different seat designs and end connections. Ball valves and needle valves with matching NPT connections are available from FITOK for the same lines.

Frequently asked questions

What does the -2 in CHSS-NS4-2 mean?

It is the cracking pressure option, giving a nominal 1 psig (0.07 bar) opening pressure.

What pressure is the valve rated for?

The product page lists 6,000 psig (414 bar).

Can it be installed in any position?

The spring-loaded poppet works in any orientation, but the flow arrow must match the flow direction.

What is the lower temperature limit?

The catalog text and product page differ (10 F or -10 F), so confirm with the manufacturer for cold service.

Does Seven Star LLC act as a FITOK distributor?

No. Seven Star LLC is not a FITOK distributor; it is an independent Muscat-based supplier that quotes FITOK products on request.

Documents and quotation

The official FITOK datasheet and user manual for CHSS-NS4-2 are hosted on this page for download. Seven Star LLC is an independent supplier in Muscat; send your quantity and delivery location through the quotation form and we will quote this item. Please confirm the exact order code, supply voltage and output options against the documents before ordering. More related products: product category.