Abstract: A method and a device for detection of metal and non-metal particle concentration of an electrical discharge machining liquid are disclosed. The method comprises steps of: (A) filling a tank with the electrical discharge machining liquid, wherein the tank comprises a tank wall, a first conductor, and a second conductor; (B) measuring a voltage between the first conductor and the second conductor by an electronic device, wherein the electronic device electrically connects to the first conductor and the second conductor, and the electronic device comprises a capacitance detection circuit; and (C) calculating a particle concentration or an equivalent dielectric constant of the electrical discharge machining liquid on the basis of the measured voltage.

Abstract: A flow meter comprising a tubular main-body and a cover plate formed by printed circuit board which carries two pressure sensing devices tightly packed by soft rubber material for sensing the pressure head of and the pressure difference between the inlet and outlet of the flow meter. Since the cover plate is mounted on, and fastened to the main-body by fastening screw, but not by adhesive to form a complete unit, the cover plate can therefore bear high fluid pressure without crack or damage, i.e., shall increase the capacity of bearing pressure, the service life and accuracy, and decrease the occurrence of malfunction to the flow meter.

Abstract: A pressure gauge comprising a thread tube, a printed circuit board carrying a pressure sensing device installed on one side of the printed circuit board and tightly packed with silicon rubber to form the end cover of the thread tube. When used for testing the pressure of acidic or alkaline liquid the pressure sensing device of the pressure gauge will not be brought into contact with the liquid, but can sense the pressure through the silicon rubber packing to test the pressure of the acidic or alkaline liquid, and the range of application of the pressure gauge covers the test of pressure of gas, acidic liquid, alkaline liquid and low pressure gas.

Abstract: A pressure gauge comprising a thread tube, a printed circuit board carrying a pressure sensing device installed on one side of the printed circuit board and tightly packed with silicon rubber to form the end cover of the thread tube. When used for testing the pressure of acidity or alkalinity liquid the pressure sensing device of the pressure gauge will not be brought into contact with the liquid, but can sense the pressure through the silicon rubber packing to test the pressure of the acidity or alkalinity liquid, and the range of application of the pressure gauge covers the test of pressure of gas, acidity liquid, alkalinity liquid and low pressure gas.

Abstract: A flow meter comprising a tubular main-body and a cover plate formed by printed circuit board which carries two pressure sensing devices tightly packed by soft rubber material for sensing the pressure head of and the pressure difference between the inlet and outlet of the flow meter. Since the cover plate is mounted on, and fastened to the main-body by fastening screw, but not by adhesive to form a complete unit, the cover plate can therefore bear high fluid pressure without crack or damage, i.e., shall increase the capacity of bearing pressure, the service life and accuracy, and decrease the occurrence of malfunction to the flow meter.