IES950354A2 - Valves for gas lines - Google Patents

Abstract

The present invention provides a valve for use in a gas line formed by plastics tubing, the valve comprising a shell portion (1) having a central chamber (7, 8) in which a plunger (15) is moveable, inlet and outlet arms (10, 11) extending from the chamber (7) and connectable to the gas line, and an exit port (12) communicating with the chamber (8) which is either open to or sealed from the gas line depending upon the position of the plunger, wherein the inlet and outlet arms (10, 11) have end portions dimensioned to receive the plastics tubing (26) internally, and the gas passages (35) inside the inlet and outlet arms (10, 11), including the opening of said passages into the central chamber, have a diameter substantially equal to the internal diameter of the plastics tubing. The valve seat (9) at the exit port (12) is offset with respect to the inlet and outlet arms (10, 11) to an extent such that when the valve head (37) with the first O-ring (16) is on the valve seat (9), in the closed position, it is out of line with the crossing (36) where the chamber (7) opens into the central chamber (7), and when the said valve head is away from the valve seat, in the open position, it is in the part of said crossing (36) nearer the exit port (12). The stem (15) of the plunger between the first and second O-rings (16, 17) has a diameter which is small compared to the diameter of the chamber (7) at a crossing (36), for example not more than 50% of the diameter of the chamber (7). The plastics tubing (26) of the gas line is nylon tubing. Each of the arms (10, 11) has an O-ring (44) which seals against the external surface of the tubing.