Range of 12, 18, 20, 24 spline Traditional Compression Tap Valves. The Rubber Washer Full Turn Screw Down Style Tap glands suit a range of kitchen and basin taps. BSP 1/2" for traditional taps and crosshead taps. If your traditional compression taps are leaking you need to replace the valve. As well as BSP 1/2" and 3/4" we also have the Older BS1010 Threaded valves. These have wider threads than modern BSP threads. The 12 spline valves suit older style taps from brands such as Bristan, Beaumont, Aqafix.