GAS MASS FLOW RATE CONTROLLER

PURPOSE:To reduce the space occupied by a pipeline casing by using a sensor pipe of the comparatively short length at a mass/flow rate sensor part and also by dividing a control base board into plural pieces. CONSTITUTION:When the gas flows through a fluid path 2, part of the gas flows through a sensor pipe 44 of a sensor part 42. Meanwhile the most of gas flows through a bypass 4 and heads for a gas using system with its flows rate controlled by a flow rate control valve 20. The flow rate of the gas flowing through the pipe 44 is detected by a compact sensor 42 of a temperature difference system. The diaphragm 22 of the valve 20 is moved up and down by an actuator 46 so that the opening degree of the valve 20 is controlled. Thus the mass flow rate of the gas can be kept at a fixed level. Meanwhile a control base board 50 is divided into plural pieces and placed side by side. At the same time, two connector parts 52 and 54 are stored above the part 42 and in parallel to a casing small-width wall part 48B. Then the cables 56 and 58 opposite to the parts 52 and 54 are attached and detached in order of larger degrees of freedom. As a result, the height of a casing 48 can be extremely reduced.