An improved high volume, straight through, low turbulent flow pressure regulating valve is provided by utilizing a hallow cylindrical valve which is selectively and telescopically disposed over an aligned conforming biscuit around which biscuit and through which valve the fluid flows. The valve does not contact the biscuit so that valve chatter is impossible. Furthermore, the absence of a valve seat or other lip reduces the turbulence introduced into fluid flow within the valve body thereby also increasing flow volume capacity. Movement of the valve is controlled in response to pressure within the valve body by means of rolling diaphragm, which is fluidically communicated to the interior of the valve body. The diaphragm, which acts as a piston, is connected between the valve body and the valve member. Increased pressure within the valve acts against the diaphragm forcing the valve member over the biscuit to reduce flow and pressure. The diaphragm, acting as a piston, acts against a prebiased spring. The amount of bias on the spring is adjusted by a collar threadably connected on the exterior of the valve. The collar is manually accessible and adjusted by turning the collar on its threaded connection to the valve body and then compressing or relaxing the compression spring against which the diaphragm acts.
