Method for surveillance of air operated diaphragm pump and surveillance device

Abstract

A method for surveillance of an air operated diaphragm pump is provided whereby initially an accelerometer with at least 3 orthogonal accelerometer measuring directions is attached to an air operated diaphragm pump or to a structure directly connected with an air operated diaphragm pump; agitation level of the accelerometer at a frequency rate above a predefined pulse rate of the air operated diaphragm pump is registered, and a base line noise level of the accelerometer agitation level during a period of no pump action is measured and stored, and a pulse rate of the air operated diaphragm pump is determined as the most significant frequency of pulses out of an entire power spectrum calculated from the accelerometer readings, and lastly the most significant frequency of pulses and the duration of registered pulse signals is determined and stored.

1 . A method for surveillance of an air operated diaphragm pump, whereby the method comprises the following steps:
 attaching an accelerometer with at least 3 orthogonal accelerometer measuring directions to an air operated diaphragm pump or to a structure directly connected with an air operated diaphragm pump,   register agitation level of the accelerometer at a frequency rate above a predefined pulse rate of the air operated diaphragm pump,   determine a base line noise level of the accelerometer agitation level during a period of no pump action,   determine the pulse rate of the air operated diaphragm pump as the most significant frequency of pulses out of an entire power spectrum calculated from the accelerometer readings,   register the most significant frequency of pulses and the duration of registered pulse signals.   
     
     
         2 . A method according to  claim 1 , wherein the frequency spectrum for accelerometer readings is determined from calculated values named aRMS i  based on sampled accelerometer readings at a sampling rate whereby, 
       
         
           
             
               
                 aRMS 
                  
                 
                   ( 
                   i 
                   ) 
                 
               
               = 
               
                 
                   
                     1 
                     M 
                   
                    
                   
                     
                       ∑ 
                       
                         k 
                         = 
                         i 
                       
                       
                         i 
                         + 
                         M 
                       
                     
                      
                     
                       
                         a 
                         2 
                       
                        
                       
                         ( 
                         i 
                         ) 
                       
                     
                   
                 
               
             
           
         
       
       and where i is the sample number, and M is the number of samples used to calculate the value aRMS, at sample number i, and further
     a   Total ( i )=√{square root over ( X   2 ( i )+ Y   2 ( i )+ Z   2 ( i ))}
 
 
       where X(i), Y(i) and Z(i) are normalized accelerometer output values in orthogonal directions x, y and z respectively in each sample. 
     
     
         3 . A method according to  claim 3 , wherein a sampling rate is selected and a number of samples M is chosen, which reflects the pulse rate of the pump, such that the number of samples M spans a time fraction of a pump pulse duration of no more than half the time of a pulse duration. 
     
     
         4 . A method according to  claim 1 , wherein an externally threaded part of an accelerometer housing is rotated into a threaded connection pipe or threaded pipe bracket located on a suction or pressure pipe to/from the air operated diaphragm pump whereby the distance between the connection pipe or bracket and the pump is adapted to be no more than 6 times the pipe diameter of suction or pressure pipe respectively, or preferably no more than 4 times the pipe diameter og most preferred no more than 2 times the pipe diameter. 
     
     
         5 . A method according to  claim 1 , wherein the method comprises the following steps
 determine the pulse rate of the air operated diaphragm pump at regular intervals and store the determined pulse rates at a data repository within the housing,   feed pulse rate data through a wireless connection channel to a remote data repository at regular intervals.   
     
     
         6 . A method according to  claim 3 , wherein a sub-giga radio in the accelerometer housing receives pulse rate data from one or more accelerometers it nearby pumps and feeds these pulse rate data through a cellular device via cellular connection to a data repository located away from the cellular device. 
     
     
         7 . A method according to  claim 1 , wherein NFC signals are captured within the housing when a NFC enabled device such as a cell phone is placed in the vicinity of the housing, and that the NFC signals are used to modify the contents of a control device which control device facilitates the accelerometer measurements. 
     
     
         8 . A method according to  claim 1 , wherein the control device is adapted to monitor a pulse rate from a pump, and to provide an alert in case pulse rates are not within predetermined limits. 
     
     
         9 . A surveillance device comprising a:
 housing and an accelerometer within the housing which accelerometer is adapted to capture acceleration data in 3 orthogonal directions in space, and a   data repository adapted to temporarily store captured acceleration data,   calculation unit adapted to determine a pump stroke rate based on the accelerometer readings,   feed line adapted to wirelessly transmit stored accelerometer data which reflects the pump stroke rate,   control device adapted to:
 control the capture of accelerometer data and to 
 process the captured data, and 
 to control the feed line and control the wireless transmission of the stored accelerometer data, 
   whereby the housing of the surveillance device comprises an externally threaded stub, which is adapted to threadedly connect to an internally threaded connection pipe or bracket at or associated with an air operated diaphragm pump.   
     
     
         10 . A surveillance device according to  claim 9 , wherein the control device is adapted to calculate an overall energy level measure based on registered accelerometer values in 3 orthogonal directions whereby a frequency spectrum for the overall energy level measure is determined from calculated values:
 aRMS(i) based on sampled accelerometer readings at a sampling rate whereby,   
       
         
           
             
               
                 aRMS 
                  
                 
                   ( 
                   i 
                   ) 
                 
               
               = 
               
                 
                   
                     1 
                     M 
                   
                    
                   
                     
                       ∑ 
                       
                         k 
                         = 
                         i 
                       
                       
                         i 
                         + 
                         M 
                       
                     
                      
                     
                       
                         a 
                         2 
                       
                        
                       
                         ( 
                         i 
                         ) 
                       
                     
                   
                 
               
             
           
         
         and where i is the sample number, and M is the number of samples used to calculate the value aRMS, at sample number i and further
     a   Total ( i )=√{square root over ( X   2 ( i )+ Y   2 ( i )+ Z   2 ( i ))}
 
 
       
       where X(i), Y(i) and Z(i) are normalized accelerometer output values in orthogonal directions x, y and z respectively in each sample. 
     
     
         11 . A surveillance device according to  claim 10 , wherein the externally threaded part of the accelerometer housing is rotated into a threaded connection pipe or threaded pipe bracket located on a suction or pressure pipe to/from the air operated diaphragm pump whereby the distance between the connection pipe or bracket and the pump is adapted to be no more than 6 times the pipe diameter of suction or pressure pipe respectively, or preferably no more than 4 times the pipe diameter og most preferred no more than 2 times the pipe diameter. 
     
     
         12 . A surveillance device according to  claim 10 , wherein the device further comprises a PCB which PCB is mounted with the control device, a radio transmitter adapted to transmit captured accelerometer data and the accelerometer. 
     
     
         13 . A surveillance device according to  claim 10 , wherein an NFC enabled communication device and a sub-giga radio is provided at the PCB. 
     
     
         14 . A surveillance device according to  claim 10 , wherein a battery is housed in the housing and connected to the PCB in order to energize the electric parts mounted thereon. 
     
     
         15 . A surveillance device according to  claim 12 , wherein the control device is adapted to provide an alarm in case the calculated pump rate is not according to expectation. 
     
     
         16 . A surveillance device according to  claim 9 , wherein a visual display is mounted on the housing.