Groco In-Line Check Valves

Groco In-Line Check Valves: Over a Century of Marine-Grade Precision

Groco has been engineering marine hardware since 1918, and their in-line check valves represent exactly the kind of no-compromise, purpose-built reliability that has made the brand a household name among boatbuilders, marine engineers, and serious cruisers. GROCO (Gross Mechanical Laboratories, Inc.) was born in the basement of a Baltimore row house , and remains a family-owned business dedicated to American manufacturing, providing durability and reliability in the challenging marine environment.

The CV Series: Bronze In-Line Check Valves

At the core of Groco's check valve lineup is the CV Series. The CV Series in-line check valve may be used in water systems or fuel systems to keep pumps primed and to prevent back-flow, and its unique design reduces flow turbulence and restriction, thus improving pump performance. These aren't generic plumbing valves — they're engineered specifically for the demands of marine environments where vibration, salt water, and fuel exposure are daily realities.

The Groco CV Series Bronze Inline Check Valve provides reliable, low-resistance flow control for marine fuel systems, constructed from durable C83600 cast bronze to prevent backflow while allowing smooth fuel delivery. NPT threaded ports and availability in 1/2" through 2" sizes make them suitable for use with both diesel fuel and gasoline. That range of sizing options means a single product family can serve everything from a small outboard fuel line to the main raw-water circuit on a large trawler.

The PNC Series: Check Valves Built from Bronze Nipples

Groco's PNC Series offers an alternative construction approach for plumbing applications. Groco PNC Series Check Valves are made from PN series cast bronze nipples with a check valve placed inside to prevent back-flow in plumbing systems. This design leverages the same high-grade bronze alloy tradition found across the entire Groco valve family, making the PNC Series a dependable choice for onboard water systems where compactness and corrosion resistance are equally important.

Why Bronze? Why Groco?

For marine check valves, material choice is everything. Groco is known for producing high-quality fittings made from bronze and stainless steel. C83600 bronze — often called "red brass" — is the marine industry's go-to alloy for underwater and wet-environment hardware because it resists dezincification and stands up to prolonged saltwater and fuel exposure far better than ordinary brass or plastic alternatives.

Groco is a leading manufacturer of high-performance marine hardware trusted by boat builders, engineers, and marine professionals around the world, specializing in seacocks, marine valves, raw water strainers, and other critical components — delivering precision, durability, and innovation backed by more than 100 years of engineering excellence. When you install a Groco check valve, you're benefiting from a lineage of design refinement that goes back to the era when boats were still being built primarily of wood and teak.

Applications: Where Groco Check Valves Earn Their Keep

• Fuel Systems: Keeps fuel pumps primed and prevents gravity-fed backflow in gasoline and diesel lines.
• Raw Water Systems: Maintains pump prime in engine cooling circuits, reducing wear caused by dry starts.
• Freshwater Plumbing: Prevents back-siphoning in pressurized onboard water systems.
• Bilge and Transfer Circuits: Stops reverse flow from flooding downstream components after pump shutoff.

Whether you're outfitting a new build or replacing an aging valve that's finally given up after years of hard service, Groco's in-line check valves deliver the quality and confidence that professional marine installers depend on. Browse the full selection of in-line check valves or explore everything Groco has to offer across their complete marine hardware range.