Brass In-Line Check Valves — High Capacity

Midland's high-capacity brass in-line check valves in one spring-loaded design — eleven sizes, two seal options, priced and orderable by size below.

Sizes: 1/4 in–4 in (11 sizes)
Connection: FNPT
Pressure: 400 PSI WOG, 175 PSI WOG
Seal: Buna-N or Viton
Cracking pressure: 1/2 psi
Lead-free: No — not lead-free

Choose your size & seal ↓

3/8 inch Brass Inline Check Valve Midland 944402

Midland's high-capacity brass in-line check valves in one spring-loaded design, offered in eleven sizes from 1/4 in to 4 in with FNPT x FNPT connections and a choice of NBR or fluoroelastomer (Viton) seal. The pressure rating varies by size: 400 WOG for 1/4 in through 2 in, and 175 WOG for 2-1/2 in through 4 in. These valves are not lead-free. Confirm the rating, seal, and media suitability for your exact size on the product page.

Not lead-free - do not use where lead-free or potable-water compliance is required. Pressure and temperature vary by size and seal; confirm the exact values for your size and seal on the product page. This product carries a California Proposition 65 warning as shown by the manufacturer.

Shared construction

Body and end connection: brass. Disc: Polyetherimide. Spring: stainless steel. Seat: soft seat, NBR or fluoroelastomer. Cracking pressure: 1/2 psi. Connection: FNPT x FNPT. Patented disc guide. Made in Italy.

Choosing a seal

NBR seal (standard part numbers): for water, oils, and general-purpose service. General working range +10 to 210 F.

Fluoroelastomer / Viton seal (the "V" part numbers, e.g. 944402V): for fuels and hydrocarbons. Maximum working temperature 325 F / 125 psi steam.

Manufacturer documentation

Midland Master Catalog 2023, p.313 — Brass In-Line Check Valves (High Capacity). NBR and fluoroelastomer (add "V" to the part number) seals; pressure by size.

Project quantities or a mixed-size order? Request a quote.

Pressure ratings by size

Maximum working pressure varies by size, calculated from the current members below. Confirm the exact rating for your size and seal on the product page before ordering.

Maximum working pressure by size range
Size range	Max working pressure
1/4 in – 2 in	400 PSI WOG
2-1/2 in – 4 in	175 PSI WOG

Questions buyers ask

What sizes and connections are available?

Eleven sizes from 1/4" to 4", all with FNPT × FNPT threaded connections. Each size is listed individually in the selector with its live price and availability.

What is the pressure rating?

Maximum working pressure is 400 psi WOG for 1/4" through 2", and 175 psi WOG for 2-1/2" through 4". Cracking (opening) pressure is 1/2 psi. Confirm the exact value for your size on the product page.

What is the difference between the standard and "V" part numbers?

The standard part number has an NBR (Buna-N) seal, suited to water, oils, and general-purpose service (+10 to 210°F). The "V" part number (for example 944402V) has a fluoroelastomer (Viton) seal for fuels and hydrocarbons, rated up to 325°F / 125 psi steam.

Are these lead-free or suitable for potable water?

No. These valves are not lead-free and should not be used where lead-free or potable-water compliance is required. They carry a California Proposition 65 warning as shown by the manufacturer.

What are the valves made of?

A brass body and end connection, a Polyetherimide disc with a patented disc guide, a stainless-steel spring, and a soft NBR or fluoroelastomer seat. They are made in Italy.

Can I order several sizes together?

Yes. Select the sizes you need in the selector and add them to the cart in one step, or use Request a quote for project quantities or mixed-size orders.

Need project quantities, a mixed-size order, or a firm lead time? Request a quote and our team will follow up.