Camlock Couplings for Fuel Transfer: Diesel, Gasoline and Lubricants

Camlock couplings are the workhorse quick-connect on fuel transfer lines — tanker trucks, bulk storage, generator refueling skids and machinery service carts all use them. But fuel is not water: the wrong material or the wrong gasket will degrade, harden or fail inside a fuel line. Here is how to spec camlocks for diesel, gasoline and lubricant duty.

Brass coupler — threaded strength and spark consideration on fuel lines.

Type B female threaded coupler for NPT fuel-line connections.

Material rules for fuel

Mixed-material rule applies here too: never pair dissimilar coupling metals (e.g. aluminum body with a brass adapter on a pressure line) — galvanic corrosion and strength mismatch are both real failure modes on fuel rigs.

The gasket is a fuel-specific decision

EPDM is the default water gasket and it is the wrong choice for fuel. EPDM swells and degrades in petroleum products.

• NBR (Buna-N) is the fuel-service standard — oil-resistant, rated for diesel, gasoline, lubricants and most mineral oils, typically -40°F to +250°F working range
• Viton (FKM) where higher temperature or aromatic/aggressive fuel blends are involved (biofuel blends, some aviation applications)
• PTFE for maximum chemical inertness, at the cost of a harder seal — used on specialty chemical fuels

For bulk fuel orders, spec NBR gaskets and a spare set — a hardened gasket is the most common cause of a fuel line leak after a season of service.

Standard layouts

• Pump to hose: Type A (male NPT) on the pump outlet → Type C (male hose shank) into the suction/discharge hose — the classic A+C pair
• Hose to tank / drum: Type D (female hose shank) on the tank fill port, Type E (male hose shank, offset) where a straight shank will not reach
• Tanker discharge: 2” to 4” aluminum, A at the valve outlet, C into layflat or hardwall transfer hose

Pressure reality on fuel lines

Fuel transfer is a low-to-medium pressure job. Reference values from the standard camlock rating table: 2” aluminum is rated around 200 psi working pressure — far above the 50-150 psi typical of transfer pumps and gravity flow. As with water service, size for flow, not pressure: 2” for up to roughly 150 gpm, 3” to ~300 gpm, 4” for bulk loading rates.

Safety checklist for fuel duty

1. Bonding and grounding — camlocks are metal, but the whole transfer system (truck, hose, receiving tank) must be bonded and grounded before flow starts. The coupling does not replace grounding.
2. Never use camlocks for pressurized gas, LPG or steam — cam and groove couplings are not rated for gas service.
3. Release pressure before uncoupling — bleed the line, then open the arms. A pressurized fuel line that comes apart sprays fuel and creates an ignition risk.
4. Inspect gaskets monthly on fuel rigs — fuel degrades rubber faster than water; look for swelling, cracks and hardness.
5. Cap open ends — dust caps and plugs keep grit out of the groove; a fuel line with a gritty seal leaks and drips.

Checklist for a fuel transfer order

• Sizes: match the hose bore (1½”, 2”, 3”, 4”)
• Types: A + C (pump to hose), D + E (hose to tank) as the layout requires
• Material: aluminum (diesel), brass (gasoline), stainless (aviation/specialty)
• Gasket: NBR (standard fuel), Viton (high-temp/aggressive blends)
• Extras: dust caps and plugs, spare gaskets

Tell us your fuel type, line sizes and pump pressure and we will confirm the coupling set — with the right gasket for the fuel.

Related guides

• Camlock gasket selection: NBR vs EPDM vs Viton — why the gasket decides fuel vs water service
• Camlock material guide: aluminum vs stainless vs brass vs PP — full comparison table
• Camlock size chart — measuring the hose bore correctly
• Camlock pressure rating chart — working pressures by material and size