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What are the parts of a stopcock key?

What are the parts of a stopcock key?

Shop for Stopcock Keys

   Parts of a stopcock key

Stopcock head

Stopcock key heads Also known as the pattern or key, this part is all-important as its shape dictates which type of stopcock it will fit.

The key on the right of the picture fits a square head, and the one on the left, a crutch head stopcock.

Head of a square head stopcock key

Square head

Some keys fit square head stopcocks only. The pipework attached to the stopcock may be 3/8 inch (10mm), 1/2 inch (15mm), 5/8 inch (16mm), 3/4 inch (20mm) or 1 inch (25mm) in diameter. A 3/8 inch (20mm) stopcock key fits a stopcock with 3/8 (20mm) pipework and so on, through to 1 inch.

However, there are some square head keys that fit more than one size.

Head of a crutch stopcock

Crutch head

Others are for crutch head stopcocks where the working end of the key is shaped like a short tunnel, or ‘U’. This is often referred to as the U-channel.

T-shaped crutch head stopcock A crutch head stopcock’s turning part is like a T-shaped tap. The U-channel of the stopcock key fits over this part of the stopcock.
Double-ended stopcock key


Some keys are double-ended. They have a different head at each end to fit various sizes of square head and crutch head stopcocks.

Stopcock shaft

Stopcock key round shaft On keys intended for use on external stopcocks, the shafts are quite long – anything from 860mm to 1060mm (2ft 10 inches to 3ft 6 inches). This is so that they can reach stopcocks that are well below ground level.
Rounded stopcock shaft

Rounded shaft

The shafts of stopcock keys for external stopcocks can be round, as seen here …

Square-shafted stopcock key

Square shaft

… or square, like the ones in this picture.

Stopcock key hexagonal shaft

Hexagonal shaft

Often, the shorter shafts of mini crutch keys, which are used on internal stopcocks, are hexagonal.

Socket and ratchet handle This is so that, if the stopcock is very difficult to turn, possibly due to having not been used for some time, a socket and ratchet handle can be attached to the end of the shaft to give greater leverage.

Stopcock handle

Stopcock key welded handle

Fixed handle

On some stopcock keys, the handle is fixed – that is, it is welded permanently to the shaft.

Stopcock key with tommy bar handle

‘Tommy bar’ handle

On some mini-stopcock keys for internal use, the handle is an adjustable and removable ‘tommy bar’. This means the handle can be moved from side to side in confined spaces, making the job of turning the stopcock much easier. On stopcock keys with hexagonal shafts, the tommy bar handle is removed when a ratchet handle is attached to the shaft.

Double-ended stopcock key with removable handle

Removable handle for double-ended keys

Some stopcock keys for external stopcocks are double-ended, with fittings on each end for different stopcock heads. This type has a removable handle that fits through holes in the head at either end, depending on which type of stopcock head is being turned.

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