RL121 - Smith Equipment 3/16" x 12.5' Grade R Acetylene Hose

Technical Overview of the Miller Smith RL121 Acetylene Hose

The Miller Smith RL121 is a specialized single-line gas hose engineered specifically for the transport of acetylene gas in oxy-fuel welding and cutting operations. Manufactured to meet stringent industrial standards, this hose is classified as Grade R, indicating its suitability for acetylene gas only. It is critical for operators to distinguish Grade R hoses from Grade T hoses; the RL121 utilizes a rubber composition that is optimized for acetylene but is not oil-resistant or suitable for use with alternate fuel gases such as propane or propylene. The hose features a distinct red outer jacket, adhering to industry color-coding standards for fuel gases, which enhances shop safety by allowing for immediate visual identification of gas lines.

With an inner diameter (ID) of 3/16 of an inch, the RL121 is designed to balance flexibility with flow capacity. This diameter is particularly well-suited for light-to-medium duty applications where maneuverability of the torch handle is paramount. The smaller diameter reduces the overall weight of the hose assembly, thereby reducing operator fatigue during extended periods of use. The hose measures 12.5 feet in length, a dimension that provides sufficient reach for standard bench-top welding stations or localized repair work without introducing the hazards associated with managing excessive hose lengths on the shop floor.

The assembly comes pre-fitted with standard "B" size hose nuts (9/16"-18 threads). These fittings are Left-Hand (LH) threaded, as indicated by the notched nuts, to prevent accidental connection to oxygen regulators or equipment. The brass fittings are factory-crimped to ensure a secure, leak-proof seal that withstands the working pressures typical of acetylene systems. This hose serves as a direct replacement for worn or damaged lines on Smith Equipment outfits and is compatible with any standard regulator or torch handle requiring a B-size acetylene connection. Regular inspection of the hose for cracks, dry rot, or abrasion is recommended to maintain the integrity of the gas delivery system.