1¼" outlet BSP female inlet nut x universal compression outlet Supplied with Tun Dish Adaptor - 1¼" BSP male thread x 22mm Universal inlet Can be used to take the discharge from a pressure relief valve on an unvented domestic hot water storage system. Please refer to guidance notes in approved Document G3 of the Building Regulations Membrane opens under water pressure to allow discharge to flow freely and then closes to form a seal to prevent foul odour or sewer gas entering the building Can be fitted in horizontal or vertical position No water seal so it can never dry out through evaporation or lack of use of an appliance as the membrane remains sealed Patent Pending