Patent ID: 7905713
Filing Date: 2011-03-15
Classification: F04B

Abstract:
1. A method for operating a reciprocating positive displacement pump for the simultaneous low-pulsation discharge of a plurality of liquids, having for a first liquid a first and second pump chamber and for a second liquid having different properties than the first liquid a third and fourth pump chamber and respective displacement devices capable of movement within each of the pump chambers, of which the first and third displacement devices take in liquid during the actual discharge phase of the second and fourth displacement devices and at the end of their intake stroke reverses their direction of movement, and, in a pre-compression phase, the first and third displacement devices pre-compress the liquid taken into their associated pump chambers and when a predeterminable pre-compression pressure has been achieved, come to a standstill, and remain at the standstill until the second and fourth displacement devices have ended their liquid discharge, and, subsequent to this discharge, begin their own discharge, wherein during the pre-compression phase of the first and third pump chambers, and alternately of the second and fourth pump chambers, a pressure compensation is carried out between the first and third, and alternately second and fourth, pump chambers and during the subsequent discharge stroke a pressure compensation between the first and third, and alternately the second and fourth, pump chambers is prevented.