Valve assembly

摘要

This relates to a valve assembly or hydrant which is particularly suitable for use in conditions where freezing temperatures may be encountered, such as in water supply systems for snowmaking equipment and the like as commonly used in ski resort areas. The valve assembly comprises a valve body, a perforated valve insert in the valve body, a control member movable along the valve insert, and a ball engaging a valve seat in the valve insert. Movement of the control member releases the ball and then progressively opens the perforation thus providing accurate and stable flow control under a wide range of back pressures. The flow closure and control are separate from one another and the shut-off is not prone to failure or fouling as a result of debris in the water supply. The valve assembly can be controlled in such a manner as to provide a straight line flow versus valve opening position function.