Sanitary constant-pressure valves for use in stainless steel pipe systems, consisting of a valve body with valve seat, cover, a valve plug with a diaphragm unit and a clamp.     CPMI-2, CPMI-D60 and CPMO-2 are sanitary constant-pressure valves for use in stainless steel pipe systems. CPMI-2 and CPMI-D60 (Constant-Pressure Modulating Inlet) maintain a constant pressure in the process line at the inlet side of the valve. Typical applications of CPMI-2 and CPMI-D60 are after separators, heat exchangers etc. and as overflow valves. CPMO-2 (Constant-Pressure Modulating Outlet) maintains a constant pressure in the process line at the outlet side of the valve. Typical applications of CPMO-2 are before filling/bottling machines etc.   The CPMI-2 and CPMO-2 consist of a valve body with valve seat, cover, a valve plug with a diaphragm unit and a clamp. The diaphragm unit consists of a stainless steel disc which is divided into sectors and of flexible diaphragms which are placed on each side of the sectors. The cover and the valve body are clamped together. The valve body and the seat are welded together. The CPM-I-D60 consists of upper and lower valve bodies, an inlet tube, a cover, a valve plug with diaphragm unit and clamps. The diaphragm unit consists of two flexible diaphragms supported by 12 stainless steel sectors in between them. The cover and the valve bodies are clamped together.