Device for monitoring fluid flow in a pump outlet

Abstract

A body ( 1 ) of permanent magnetic material is arranged to be able to move freely back and forth in the liquid flow in the pump outlet ( 3 ), the position of the body being decided by the intensity of the flow. A tongue element ( 4 ), which is located in a room separated from the pump outlet ( 3 ) by a wall, is influenced by the magnetic field from the body ( 1 ) and can thereby detect the position of the body and consequently the intensity of the flow. This knowledge is used to stop the energy supply of the pump motor when the intensity of the flow reaches a certain minimum value.

1 . A detecting and monitoring device for the liquid flow in a pump outlet ( 3 ) to be used for controlling the current supply to the electrically driven pump motor in order to avoid dry running of the pump when the water level in the pump inlet is low, characterized in, 
 that a body ( 1 ) of permanent magnetic material is located within the liquid flow and is arranged to be able to make a limited movement therein, mainly back and forth in the direction of said flow,    that the body ( 1 ) takes a front position as seen in the direction of the flow at a flow intensity over a certain value,    that the body ( 1 ) takes a rear position as seen in the direction of the flow, at a flow intensity below said value,    and that a tongue element ( 4 ) is located in a room separated from the fluid flow, said element ( 4 ) detects the location of the body ( 1 ) and initiates stop of the current supply to the pump motor when the body ( 1 ) approaches or takes its rear position as seen in the direction of the flow.    
     
     
         2 . A detecting and monitoring device according to  claim 1 , characterized in, 
 that the body ( 1 ) has a density higher than that of the pumped medium and is located in a cage ( 2 ) which restricts its movement,    that the body takes its highest possible position within the cage ( 2 ), the front position as seen in the direction of the flow, at a flow intensity over a certain value,    that the body ( 1 ) takes its lowest possible position within the cage ( 2 ), the rear position as seen in the direction of the flow, at a flow intensity below said value.    
     
     
         3 . A detecting and monitoring device according to  claim 2 , characterized in, 
 that the body ( 1 ) is designed like a massive or hollow cylinder and that the cage ( 2 ) has a width and a length that allows the body ( 1 ) to move with a considerable play.    
     
     
         4 . A detecting and monitoring device according to  claim 2 , characterized in, 
 that the cage ( 2 ) is designed with an upwards decreasing area in order to facilitate the movement of the body ( 1 ) in cases when the direction of the flow deviates from the vertical line.    
     
     
         5 . A detecting and monitoring device according to  claim 1 , characterized in, 
 that the body ( 1 ) is connected to a rocker which can pivot around an axle perpendicular to the direction of the flow and thereby is able to take different positions with reference to the direction of the flow.    
     
     
         6 . A detecting and monitoring device according to  claim 5 , characterized in, 
 that the rocker is spring loaded in the direction opposite the flow direction.    
     
     
         7 . A detecting and monitoring device according to  claim 1 , characterized in, 
 that the body ( 1 ) is connected to an arm, which can pivot around an axle perpendicular to the wall of the pump outlet and thereby is allowed to take different positions with reference to the direction of the flow.    
     
     
         8 . A detecting and monitoring device according to  claim 1 , characterized in, 
 that the body ( 1 ) is connected to a spring element which can change its position with reference to the direction of the flow at a certain flow intensity.