B K Mueller 521-310HC Black Reducing Coupling 1/4x1/8 25pk

Product Description

The B K Mueller Industries 521-310HC is a black reducing coupling designed to connect pipes or fittings of two different sizes in a threaded piping system. It transitions from a 1/4-inch connection to a 1/8-inch connection, making it a practical solution for low-pressure gas, air, or fluid distribution lines where a size change is needed without additional adapters. This coupling ships in a package of 25 units, making it well suited for contractors, service technicians, and supply house stocking. The black finish indicates malleable iron construction, standard for gas and air distribution in trade applications.

This reducing coupling is used in residential and light commercial piping systems where threaded connections are required. Typical applications include natural gas and propane distribution lines, compressed air systems, and general plumbing rough-in work. Plumbers, pipefitters, and HVAC technicians regularly use fittings of this type when transitioning between pipe sizes at branch connections, meters, or equipment hookups. The pack quantity of 25 supports high-volume service work or contractor inventory replenishment.

Key Features

• Reduces from 1/4-inch to 1/8-inch threaded connection
• Black finish construction typical of malleable iron gas and air fittings
• Sold in a pack of 25 units for contractor and stocking use
• Threaded design compatible with standard NPT pipe systems
• Compact reducing coupling eliminates need for separate adapters

Compatibility

Designed as an OEM-style replacement and standard fitting for threaded 1/4-inch to 1/8-inch NPT piping systems in gas, air, and fluid distribution applications.

Installation Notes

Installation is performed by licensed plumbers, pipefitters, or HVAC technicians following applicable local codes, IFGC, and IPC standards. Shut off the gas or fluid supply and depressurize the line before making or breaking any threaded connections. Apply an approved pipe thread sealant or PTFE tape rated for the specific media being carried. Do not overtighten threaded fittings, as this can crack malleable iron at the threads.