Stopcock keys that can be used on different types and sizes of stopcock, such as a combination, double-ended or ‘universal’ key, are usually the ones used by water board engineers and officials and professional plumbers. This is because they are likely to encounter a wide range of different stopcocks in their line of work.
An individual householder will probably only need one kind of stopcock key to fit their particular external stopcock…
…and perhaps a mini stopcock key to fit an internal stopcock and wheel head valves in case they prove difficult to turn at the crucial moment.
If your external stopcock has a crutch head and is quite close to ground level, you may be able to use a mini crutch stopcock key for both your external and internal stopcocks.
However, it’s unlikely that crutch keys for external stopcocks can be used on indoor stopcocks as the shafts will most likely prove to be too long and unwieldy due to space restrictions set by cupboards, pipework and possibly other fixed objects.
Check what type of external stopcock you have – whether it has a crutch head (a T-shaped tap-style turning handle) or a square head.
Make a note of this, and whether the pipework is 1/2 inch (15mm), 3/4 inch (20mm) or some less common size, before buying a key that fits your particular type.
Your internal stopcock will most likely be of the crutch head type.
Mini crutch keys and wheel head combination keys should fit all types of internal stopcock and most wheel head valves.