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What are the different types of stopcock key?

What are the different types of stopcock key?

Stopcocks are external devices that control the flow of mains gas or water supply to a house. A stopcock key is the tool used to turn the supply of water or gas on and off.

Square Head Stopcock Key

The square head stopcock key works on one type of stopcock, those with heads (the visible turning part that the key fits on to) that are square in shape.

The square heads come in various sizes to fit stopcocks with pipe sizes from 3/8 inch (10mm) up to 1 inch (25mm), with 1/2 inch (15mm), 5/8 inch (16mm) and 3/4 inch (20mm) in between. The most common sizes are 1/2 inch (15mm) and 3/4 inch (20mm).

You can buy a square head key that fits just one size, or there are versions that fit several sizes, like this one, with one square recess inside another.

Crutch Head Stopcock Key


A crutch head or crutch pattern stopcock key fits stopcock heads that look like traditional T-shaped taps, called crutch head/pattern stopcocks or stop valves. The ‘U’ shaped working end of a crutch stopcock key usually fits stopcocks with fittings for 1/2 inch (15mm) and 3/4 inch (20mm) pipework, the most common sizes.

Combination Stopcock Key

A combination stopcock key has heads of different shapes to fit crutch head stopcocks and square head stopcocks, all on the same working end of the tool.

It is sometimes called a ‘multi-purpose’ key and even a ‘universal’ key. Inside the combination key’s crutch head are square recesses that operate square head stopcocks.

This makes it versatile – it can fit most 1/2 inch (15mm) and 3/4 inch (20mm) stopcocks of both the crutch head and square head types.

Double-Ended Stopcock Key

Another key that can handle different sizes of both crutch and square head stopcock is the double-ended key. Again, some manufacturers and retailers call this a ‘universal’ key or a ‘multi-purpose’ key. There is a crutch head key at one end and a multiple square head key at the other.

Each head has a hole through it. A removable handle fits into either end, depending on which shape of stopcock head is to be turned.

One version of the double-ended, universal key fits six different stopcock heads – 1/2 inch (15mm) and 3/4 inch (20mm) crutch head pattern stop valves and 1/2 inch (15mm), 5/8 inch (16mm), 3/4 inch (20mm) and 1 inch (25mm) square head valves.

Mini Crutch Stopcock Key

A mini crutch stopcock key has a short shaft and is used on internal stopcocks that have proved difficult to turn. A variation is the mini crutch and wheel head combination stopcock key. This key has two metal tabs, or teeth, one on each bottom edge of the U-shaped crutch.

The teeth fit between the spokes of the wheel on a wheel head valve, making it much easier to turn.

Indoor Stopcock Keys and Outdoor Stopcock Keys

Due to the different needs for using a stopcock key indoors and outdoors, stopcock keys are more suited to different environments. Indoor stopcock keys are usually smaller as they don’t need to reach as far. Outdoor stopcock keys are much larger as typically they are used in drains or underground where stopcocks are out of reach.

Outdoor Stopcock Keys

Square head, crutch, combination, double-ended, multi-purpose and universal stopcock keys are generally for use on outdoor, or external, stopcocks set below ground level.

Inside Stopcock Keys

Mini crutch stopcock keys, including the mini crutch and wheel head combination key, are usually used on indoor, or internal, stopcocks.

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