Provided is a boomer that is a type of a seismic source generator for marine seismic survey. The valve uses a spherical member, such as a ball bearing, to depress an elastomeric member to selectively open and close a microfluidic channel. The pouring electrical furnace can be used for treating the molten spheroidal graphite iron. The MFC includes an orifice, a mass flow control gate, an actuator and a gate position sensor. The opening of the groove is closed by the second sheet glass. When CPU 17 detects any one of these alarms, the CPU 17 changes a threshold value of the driving circuit so as to fix the output of the driving circuit.