The coupling standard depends on the fire hydrant system already installed on your vessel or dock. American type couplings are common on US-built vessels and USCG-compliant systems. Machino couplings are widely used in Asia-Pacific and on vessels built to Japanese standards. Nakajima is another Japanese standard used on commercial and fishing vessels. GB fittings are used on vessels built to Chinese classification society requirements. EU German standard fittings comply with European DIN norms. If you are unsure, check the existing coupling on your vessel’s fire hydrant outlet or consult your vessel’s fire safety documentation.

The size numbers generally refer to the nominal bore diameter of the coupling in millimeters — 40mm (≈1-1/2"), 50mm (≈2"), 65mm (≈2-1/2"), and 80mm (≈3"). Select the size that matches your existing hose and hydrant outlet diameter. Mixing sizes will result in an incompatible connection.

The KA89 brass fire cap (blind cap) is used to seal and protect a fire hydrant outlet when it is not in use, preventing debris, corrosion, and accidental water discharge. It is a thickened design for added durability. The stainless steel chain variant is available separately to tether the cap to the hydrant body so it cannot be lost.

Yes. The main coupling bodies are manufactured from copper alloy, which provides good corrosion resistance in both fresh and saltwater environments. The thickened wall construction on GB, EU German, and KA89 variants adds additional durability. The stainless steel chain is specifically chosen for its corrosion resistance in marine conditions.

Pressure ratings vary by coupling standard and size. Marine fire hydrant couplings are generally rated for the working pressures specified by their respective standards (American, Machino, Nakajima, GB, or EU DIN). Contact us to confirm the pressure rating for your specific variant before use in a pressurized fire suppression system.

Thickened variants (GB, EU German, and KA89) feature increased wall thickness compared to standard-wall couplings, providing greater mechanical strength and resistance to impact and deformation. These are recommended for applications where the fitting may be subject to rough handling, high-pressure use, or frequent connection and disconnection cycles.

The stainless steel chain is designed to tether a blank (blind) cap to the hydrant body, preventing it from being misplaced. It is generally compatible with standard marine fire hydrant caps that have a suitable attachment point. Confirm the attachment method on your specific cap before ordering the chain separately.