Abstract: A valve capable of controlling fluid flow at high temperatures and high-pressures. The valve can shut off or regulate flow and combines a small compact shape with the ability to be remotely operated and the ability to process a diverse variety of fluids including polymer melts at extreme temperatures and pressures including two phase fluids. The valve includes a process diaphragm that deflects to seat against a valve seat, a control diaphragm that deflects to contact against a stop surface, and a cylindrical actuating button therebetween. The actuating button has respective end surfaces that contact against the process diaphragm and the control diaphragm. The button end surfaces on the button are spaced apart by a button length. When assembled, the distance between the valve seat and the stop surface is greater than the button length by about the sum of the deflections of the diaphragms.