Method to prolong lifetime of diaphragm pump

Abstract

A method for operating a diaphragm-type piston pump prolongs the life of the diaphragm. A pump has a predetermined pump volume defined by a length of a piston stroke. The pump having a variable drive. The method includes drawing a first volume of liquid into the pump through a first portion of the piston stroke. The first volume of liquid is less than the pump volume. The first volume of liquid is expelled from the pump through a reverse motion through the first portion of the piston stroke. A second volume of liquid is drawn into the pump through a second portion of the piston stroke. The second volume of liquid is less than the pump volume. The second volume of liquid is expelled from the pump through a reverse motion through the second portion of the piston stroke. At least portions of the first and second portions of the piston stroke are different from one another.

1 . A method for operating a diaphragm-type piston pump, the pump having a predetermined pump volume defined by a length of a piston stroke, the pump having a variable drive, the method comprising the steps of:
 drawing a first volume of liquid into the pump through a first portion of the piston stroke, the first volume of liquid being less than the pump volume;   expelling the first volume of liquid from the pump through a reverse motion through the first portion of the piston stroke;   drawing a second volume of liquid into the pump through a second portion of the piston stroke, the second volume of liquid being less than the pump volume; and   expelling the second volume of liquid from the pump through a reverse motion through the second portion of the piston stroke,   wherein portions of the first and second portions of the piston stroke are different from one another.   
   
   
       2 . The method in accordance with  claim 1  wherein the first and second volumes of liquid are equal. 
   
   
       3 . The method in accordance with  claim 1  wherein the step of drawing the second volume of liquid immediately follows the step of drawing the first volume of liquid. 
   
   
       4 . The method in accordance with  claim 1  including the steps of:
 drawing a third volume of liquid into the pump through a third portion of the piston stroke, the third volume of liquid being less than the pump volume; and   expelling the third volume of liquid from the pump through a reverse motion through the third portion of the piston stroke,   wherein the second and third portions of the piston stroke are different from one another.   
   
   
       5 . The method in accordance with  claim 4  wherein the third portion of the piston stroke is different from the first portion of the piston stroke. 
   
   
       6 . The method in accordance with  claim 5  wherein the first, second and third portions of the piston stroke are carried out in succession. 
   
   
       7 . The method in accordance with  claim 1  wherein the steps of drawing the first volume of liquid into the pump and expelling the first volume of liquid from the pump are carried out repeatedly for a first predetermined period of time and the steps of drawing the second volume of liquid into the pump and expelling the second volume of liquid from the pump are carried out repeatedly for a second predetermined period of time following the first predetermined period of time. 
   
   
       8 . The method in accordance with  claim 7  including the steps of:
 drawing a third volume of liquid into the pump through a third portion of the piston stroke, the third volume of liquid being less than the pump volume; and   expelling the third volume of liquid from the pump through a reverse motion through the third portion of the piston stroke,   wherein the steps of drawing the third volume of liquid into the pump and expelling the third volume of liquid from the pump are carried out repeatedly for a third predetermined period of time following the second predetermined period of time.   
   
   
       9 . The method in accordance with  claim 1  wherein the steps of drawing the first volume of liquid into the pump and expelling the first volume of liquid from the pump are carried out repeatedly for a first predetermined number of strokes and the steps of drawing the second volume of liquid into the pump and expelling the second volume of liquid from the pump are carried out repeatedly for a second predetermined number of strokes following the first predetermined number of strokes. 
   
   
       10 . The method in accordance with  claim 9  including the steps of:
 drawing a third volume of liquid into the pump through a third portion of the piston stroke, the third volume of liquid being less than the pump volume; and   expelling the third volume of liquid from the pump through a reverse motion through the third portion of the piston stroke,   wherein the steps of drawing the third volume of liquid into the pump and expelling the third volume of liquid from the pump are carried out repeatedly for a third predetermined number of strokes following the second predetermined number of strokes.   
   
   
       11 . The method in accordance with  claim 9  wherein each the first and second predetermined number of strokes is greater than one. 
   
   
       12 . The method in accordance with  claim 10  wherein each the first, second and third predetermined number of strokes is greater than one. 
   
   
       13 . The method in accordance with  claim 9  wherein the first volume of liquid and second volumes of liquid are substantially equal. 
   
   
       14 . The method in accordance with  claim 10  wherein the first, second and third volumes of liquid are substantially equal. 
   
   
       15 . The method in accordance with  claim 1  wherein portions of the first and second portions of the piston stroke overlap. 
   
   
       16 . The method in accordance with  claim 1  wherein no portions of the first and second portions of the piston stroke overlap.