Reducers

What is a reducer?

A reducer is a transition fitting used to connect two pipes or fittings of different diameters. When the size of a pump port, valve, meter, or fixture in a plumbing system differs from the pipe run, a reducer is used to make the diameter transition. For example, a 1/2–3/8 inch reducer is used to connect a 1/2 inch line to a 3/8 inch fixture. The correct reducer provides a leak-free transition without the need for additional fittings.

Reducer types

• Male-female reducers (bushings): One end male thread, the other female thread; for reducing a fitting port.
• Female-female reducers: For connecting two male-threaded pipes of different sizes.
• Brass reducers: Corrosion-resistant; for drinking water and hot water.
• Galvanized reducers: For economical general use.

Reducing nipples can also be used as an alternative for size transitions.

Points to note in pump installations

Avoid using a reducer in a way that narrows the pump suction port; reducing the diameter on the suction side makes it harder for the pump to prime and increases the risk of cavitation. On the pump suction side, the pipe diameter should generally be equal to or larger than the pump port. On the discharge side, the pipe diameter is determined by the required flow rate and line length; unnecessary reductions increase friction losses. Using an eccentric reducer on horizontal suction lines is a preferred practice to prevent air pocket formation.

Installation

PTFE tape should be used on threaded reducers and the fitting should not be overtightened. Brass fittings are soft and must be tightened carefully. After installation, pressurize the line to check for leaks.

Frequently asked questions

Are a reducer and a bushing the same thing?

Male-female reducers are also commonly referred to as bushings.

Does a reducer reduce flow?

Since the diameter decreases, some loss occurs; it should be used with care especially on the pump suction line.

Where is a 1/2–3/8 reducer used?

It is used to connect 3/8 inch fixtures — such as sink and cistern connections — to a 1/2 inch line.

Brass or galvanized?

Brass reducers are more durable in hot water and drinking water lines.

What other fittings might I need besides a reducer?

You can browse the fittings and materials category for all fittings products.

Can I use a different pipe size instead of a reducer?

If the existing parts have different thread sizes, a reducer is still needed for the transition; in new installations, planning compatible sizes from the outset requires fewer fittings.