1,181,863. Valves. FLAIR MFG. CORP. 12 July, 1967 [14 Oct., 1966], No. 31997/67. Heading F2V. The gate member 15 of a valve is biased by means, such as a spring 17, to an open position and is closed when the pressure at outlet 13 acting on a diaphragm 18 exceeds a predetermined value, the gate member being connected to a resilient check valve 19 and being movable to the open or closed position by manual means which override the influence of the spring and the diaphragm. The manual means consists of a cap 25 which may be depressed to hold the valve member open or rotated on a threaded stem until it abuts a surface 27 and the valve member is closed.