Proto J3764 Open End Flare Nut Wrench 3/8 X 7/16 in

Product Description

The PROTO J3764 is a double-end open end flare nut wrench designed for gripping flare fittings on refrigerant lines, fuel lines, and hydraulic connections without rounding the nut. The wrench spans 3/8 inch and 7/16 inch openings, providing two of the most commonly needed sizes in a single tool. Constructed from steel with a chrome finish, it measures 6.25 inches overall length and weighs 0.17 pounds. The 6-point jaw contact pattern distributes force evenly across the nut flats, reducing the risk of damage to soft fittings during service. HVAC technicians, plumbers, and automotive technicians reach for this style of wrench when working on flared tube connections where a standard open end wrench would slip.

This wrench is suited for residential and light commercial HVAC service involving flare fittings on copper refrigerant lines, as well as plumbing applications with compression-style flare connections. The double-end design makes it practical in tight spaces where repositioning tools is inconvenient. It is appropriate for use on brass and steel flare nuts in sizes 3/8 inch and 7/16 inch across flat, common in both refrigeration and fuel line work.

Key Features

• Double-end head with 3/8 inch and 7/16 inch openings in one tool
• 6-point jaw contact reduces rounding on flare nuts
• Chrome finish over steel construction for corrosion resistance
• 6.25 inches overall length fits into standard tool pouches
• Lightweight at 0.17 pounds for reduced hand fatigue during overhead work

Compatibility

Designed as an OEM-style service wrench for flare nut applications requiring 3/8 inch or 7/16 inch across-flat sizing, typical in residential HVAC refrigerant piping, fuel line, and hydraulic fitting service.

Installation Notes

Licensed HVAC technicians and plumbers typically use flare nut wrenches during refrigerant line connection and fuel line service. Always depressurize the line and recover refrigerant per EPA Section 608 regulations before loosening flare fittings on refrigerant circuits. Position the wrench fully seated on the nut flats before applying torque to avoid slippage. Do not use extension bars or pipe cheaters on this wrench, as overloading the jaw can damage soft brass fittings.