Check Valves for Instrumentation Service

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How the valve works

A spring holds a poppet on the inlet seat. Forward flow lifts it at the cracking pressure; reverse flow pushes it back, and the valve reseals without help. It has no handle and no stem packing, so it cannot be left open by mistake.

Cracking and reseal pressure are separate figures. A 1/3 psig valve cracks at 3 psig (0.21 bar). A 10 psig (0.69 bar) valve cracks between 7 and 15 psig (0.48 to 1.0 bar). The 25 psig (1.7 bar) valve reseals between 16 and 22 psig.

Four series and their ratings

SPCV has a two-piece body, Cv 0.1 to 4.5, and is rated 3,000 psig (207 bar) at 70 F (20 C) to 375 F (190 C) with the standard FKM seal.

The high-pressure SHCV comes in three bore sizes: SHCV1 and SHCV2 at 6,000 psig (414 bar), SHCV3 at 5,000 psig (344 bar). SOCV and SOACV use a one-piece body rated 3,000 psig (207 bar).

Materials, seals and ends

Body, inlet, outlet, insert and actuator are 316 stainless steel to ASTM A479 and springs are 304 stainless steel. Brass B16 is offered for SPCV, SOCV and SOACV. SHCV trim adds a 316 stainless steel actuator stop with PTFE O-ring and PTFE backing ring.

Tube ends run 1/8 in to 1 in OD (codes 2 to 16) and 3 mm to 25 mm (codes 3M to 25M). Threaded ends run 1/8 in to 1 in in NPT female, NPT male and ISO tapered threads, coded N and R.

Standards referenced: NPT threads to ASME B1.20.1; ISO tapered (PT/BSPT) to ISO 7-1; Body, insert and actuator bar stock to ASTM A479; plate to ASTM A240; Pressure and temperature ratings as design references following ASME B31.3; the catalogue rating curve governs selection.

Typical duties: Instrument air and utility distribution; Hydraulic and pneumatic control panels; Analyzer and sampling systems; Chemical injection and dosing skids; Semiconductor and high-purity gas cabinets; Hydrogen, CNG and nitrogen blanketing.

Check valve model selection guide

Series / model	Size	Connection	Working pressure	Body material	Cv
SPCV (S2 / F2N)	1/8 in.	Tube fitting 1/8 in. or 1/8 NPT female	3000 psig (207 bar) at 70 degF (20 degC)	316 stainless steel / A479	0.1 / 0.47
SPCV (S4 / F4N)	1/4 in.	Tube fitting 1/4 in. or 1/4 NPT female	3000 psig (207 bar) at 70 degF (20 degC)	316 stainless steel / A479	0.47
SPCV (S6 / F6N)	3/8 in.	Tube fitting 3/8 in. or 3/8 NPT female	3000 psig (207 bar) at 70 degF (20 degC)	316 stainless steel / A479	1.47
SPCV (S8 / F8N)	1/2 in.	Tube fitting 1/2 in. or 1/2 NPT female	3000 psig (207 bar) at 70 degF (20 degC)	316 stainless steel / A479	1.68
SPCV (S10)	5/8 in.	Tube fitting 5/8 in.	3000 psig (207 bar) at 70 degF (20 degC)	316 stainless steel / A479	2.6
SPCV (S12 / F12N)	3/4 in.	Tube fitting 3/4 in. or 3/4 NPT female	3000 psig (207 bar) at 70 degF (20 degC)	316 stainless steel / A479	4.5
SPCV (S16 / F16N)	1 in.	Tube fitting 1 in. or 1 NPT female	3000 psig (207 bar) at 70 degF (20 degC)	316 stainless steel / A479	4.5
SHCV1 (S2 / S4 / S6M / F4N / M2N / M4N)	4.8 mm bore; 1/8 in., 1/4 in. and 6 mm tube	Tube fitting 1/8 in., 1/4 in. or 6 mm; 1/4 NPT female; 1/8 or 1/4 NPT male	6000 psig (414 bar) at 70 degF (20 degC)	316 stainless steel / A479	0.67
SHCV2 (S6 / S8 / S8M / S10M / S12M / M6N / M8N)	7.8 mm bore; 3/8 in., 1/2 in., 8, 10, 12 mm tube	Tube fitting 3/8 in., 1/2 in., 8 mm, 10 mm or 12 mm; 3/8 or 1/2 NPT male	6000 psig (414 bar) at 70 degF (20 degC)	316 stainless steel / A479	1.8
SHCV2 (F6N)	7.8 mm bore; 3/8 in. tube equivalent	3/8 NPT female, 64.8 mm overall	5000 psig (344 bar) at 70 degF (20 degC)	316 stainless steel / A479	1.8
SHCV2 (F8N)	7.8 mm bore; 1/2 in. tube equivalent	1/2 NPT female, 77.0 mm overall	4600 psig (317 bar) at 70 degF (20 degC)	316 stainless steel / A479	1.8
SHCV3 (S12)	15 mm bore; 3/4 in. tube	Tube fitting 3/4 in.	5000 psig (344 bar) at 70 degF (20 degC)	316 stainless steel / A479	4.7
SHCV3 (S16)	15 mm bore; 1 in. tube	Tube fitting 1 in.	4700 psig (323 bar) at 70 degF (20 degC)	316 stainless steel / A479	4.7
SHCV3 (S22M / S25M)	15 mm bore; 22 mm and 25 mm tube	Tube fitting 22 mm or 25 mm	5000 psig (344 bar) at 70 degF (20 degC)	316 stainless steel / A479	4.7
SHCV3 (F12N)	15 mm bore; 3/4 in. tube equivalent	3/4 NPT female	4300 psig (296 bar) at 70 degF (20 degC)	316 stainless steel / A479	4.7
SHCV3 (F16N)	15 mm bore; 1 in. tube equivalent	1 NPT female	4100 psig (282 bar) at 70 degF (20 degC)	316 stainless steel / A479	4.7

Selection notes: The orderable part number is the series plus a six-part code (example SOCV1-M-4N-1P-N-B = series, end type, end size, cracking pressure, seal material, body material); the catalogue size tables list the series and end sizes only. SPCV Cv values are printed only as curve labels, not as a table column; the values above are the curves labelled Cv 0.1, 0.47, 1.47, 1.68, 2.6 and 4.5.

Catalogue reference 11-01, 11-02, 11-05, 11-06, 11-09, 11-10, 11-11, 11-12. Confirm the final rating against the data sheet issued with your order.

See also: Ball Valves · Diaphragm Valves · Gauge Valves Manifolds · Needle Valves · Plug Valves · Pressure Regulators · Purge Bleed Valves · Safety Relief Valves

Frequently asked questions

What is the minimum order quantity and lead time?

Small trial orders are accepted, and a single standard catalogue valve can be quoted. Availability depends on size, seal and body material, because brass bodies and Kalrez or Neoprene seals are made to order. Send item codes, quantities and destination port.

Which documents are issued with the valves?

Material certificates for body and trim, a dimensional inspection report and the cracking and reseal test record can be issued with the shipment. Tell us at enquiry stage if the documents must be third-party certified or reviewed before dispatch.

What thread form should I specify?

NPT (code N) and ISO tapered threads (code R) are catalogued from 1/8 in to 1 in. NPT follows ASME B1.20.1 and ISO tapered threads follow ISO 7-1. Match the mating part on your panel and keep male and female ends consistent.