Constant pressure valve and method

Abstract

A flow control valve is provided of the type useful for positioning in a fluid system between a high pressure pump and a fluid gun. The valve preferably includes a body having first and second flow paths therein, and first and second valve members for controlling the fluid flow through the respective flow paths. The first valve member is biased towards engagement with the first seat, and the second valve member serves to substantially restrict fluid flow through the second flow path to maintain a high pressure level upstream from the valve when the gun is deactivated. The second valve seat member may be easily replaced through an access port provided in the body, and adjustment of the second valve member to control the restricted orifice in the second fluid path is obtained with a rachet mechanism. According to the method of the present invention, the gun is activated to increase pressure downstream from the valve and thereby move the first valve member to an open position, and deactivation of the gun closes the first valve member and causes a small quantity of low pressure fluid to flow to the gun, while the desired high pressure upstream from the valve is maintained.