| 摘要 |
<p>METERING PULSE PUMP A metering pulse pump for metering an additive liquid into a liquid carrier under high pressure. A high-pressure, rapidly reciprocating piston pump is provided at its outlet end with a pressure-relief valve including a spring pressure control permitting the valve to open under varying pre-set pressure differentials across the valve. A diaphragm pump having first and second chambers separated by a diaphragm is provided with one of the chambers communicating directly with the outlet of the piston pump upstream of the pressure-relief valve, liquid carrier emitted under pressure from the piston pump serving to drive the diaphragm pump in a pumping stroke, the second chamber of the diaphragm pump having inflow and outflow ports with respective check valves permitting only inflow and outflow of an additive liquid into and out of the second chamber. The first and second chambers of the diaphragm pump are communicated through a manually closable bleeder duct having a check valve permitting flow only from the first chamber to the second chamber when the duct is open. The length of a diaphragm pumping stroke corresponding to a rapid piston pump stroke is controlled by the pressure differential setting of the pressure-relief valve.</p> |
