We stock a range of imperial brass threaded plumbing fittings, available in BSPP thread.
Typical uses and sizes are:
1/4" - Compressed air connections
3/8" - Oil line connections
1/2" - Bathroom basin and kitchen sink taps, radiator inlets, old outside tap outlets
3/4" - Bath taps, washing machine inlet hose connections, modern outside tap outlets
1" - Domestic heating boilers and hot water cylinders
1 1/4" - Wash hand basin wastes (bathroom sink)
1 1/2" - Kitchen sink wastes, bath wastes, toilet syphon outlets
2 1/4" - Immersion water heater elements
Note: The sizes of brass threaded plumbing fittings relate to the inner diameter of tube for which the thread is intended, and not the outside diameter of the male thread.