Pressure sand storage tank copper air inlet valve copper exhaust valve Shanghai Dingxie Machinery Copper air inlet valve for pressure sand storage tanks Copper exhaust valve Shanghai Dingxie Machinery Shanghai Dingxie Mold Machinery Co., Ltd. is a company specializing in the production of air inlet valves, exhaust valves, filters, abrasive valves, and material level meters for pressure sand storage tanks. and processing enterprises, the company since