The flow rate controller type 8750 represents a closed flow control loop to measure and control gases using the differential pressure principle. The reliable and robust system consists of an ELEMENT control valve, type 2301, the compact process controller type 8693 put on top of the valve and two pressure transmitters, type 8325. The Bürkert flow rate controller does not need a separate flow meter. The valve seat serves as variable orifice. From the pressure difference across the valve and the given density and temperature a volume flow, referring to the conditions programmed, can be calculated. For that the process controller uses the flow characteristics of the valve and the scales of the pressure transmitters programmed. The volume flow set can then be adjusted by changing the stroke of the control valve. The flow rate controller offers a high repeatability and large measuring range. Beneficial is that the control itself is used for both, controling the flow and measuring over an orifice. With the variable orifice of the control valve the measurement range is increased significantly. Low assembly costs and easy commissioning are further advantages of this unique product.