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Morehouse Digital Proving Ring

TARE LOAD CORRECTION USING COMPUTED LOAD TABLES

1.                  Exercise the Proving Ring and take readings to determine the tare load and record the Proving Ring temperature.
      0.0 div.                  Ring no load reading before application of tare load
    98.2 div.                  Ring reading for calculation of tare load
      0.15div.                 Ring no load reading after application of tare load
    23.5O C                    Ring temperature

2.                  Calculate average no load reading for the tare load.
     0.0 div.                   Ring no load reading before application of tare load
   +0.15 div.                 Ring no load reading after application of tare load
     0.15/2 = 0.075div. Average no load reading to calculate tare load

3.                  Determine net deflection for tare load.
     98.20 div.   Ring reading for calculation of tare load
    -  0.075 div.             Average no load reading to calculate tare load         
     98.125 div.             Net Ring deflection to calculate tare load at 23.5

4.                  Compensate net Ring deflection of tare load for temperature.
    98.125 div.  Net Ring deflection to calculate tare load at 23.5
    - 0.075 div.   Correction to 23 using the formula on page 17 of the Operation                            and Maintenance Instructions For Proving Rings manual.
     98.1135 div.           Net Ring deflection to calculate tare weight at 23.5

5.                  Determine weight of tare load from computed load table.
     98.1135 div.           Net Ring deflection to calculate tare load at 23

      98.1135div. =  299.70 lbf interpolation from load table
                                                                              
      98.1135 div. =  299.70 lbf force of tare load*

6.                  Exercise the Proving Ring and take readings for the applied load.
     98.20 div.               Ring reading with only tare load applied before application of load
 1105.05 div.               Ring reading with applied load including tare load
      98.30div.               Ring reading with only tare load applied after application of load
     23.5O C                   Ring temperature

7.                  Calculate average no load reading for the applied load.
       98.20 div.             Ring reading with only tare load applied before application of load
  +   98.30 div.             Ring reading with only tare load applied after application of load
       196.50/2 = 98.25 Average no load tare reading for applied load

8.                  Determine net deflection for applied load including the tare load.
       1105.05 div. Ring reading with applied load at 23.5
 -        98.25 div.  Net Ring Deflection to calculate tare at 23.5
        1006.8 div. Change in Net Ring deflection

9.                  Compensate net Ring deflection of load for temperature.
   1006.80 div.             Net Ring deflection including tare at 23.5
   -     0.13 div.  Change in Net Ring deflection
                           1006.67 div.  Net Ring Deflection Including Tare Load

  
TARE LOAD CORRECTION USING TARE LOAD CORRECTION FACTOR

The following is an example that uses a formula to correct for tare loads.  The tare load correction formula corrects for tare and is applied to the value of the applied load from the fitted curve data provided with your calibration report.  The tare load correction formula is represented as follows:       TCF =  (2c * L * T) - a 
                       
Where:      c = The value of the c constant found on the ring calibration report
                                         L = The force of the load being applied
                                         T = The force of the tare being applied    
                             a  = The value of the a constant found on the ring calibration report

Calibration Report Data:   c = 0.2648421D-05
                              L = 3,000.00
                              T= 299.70 Lbf                                          
                                          a = 0.1673432D+00         
                                               
                                               TCF = (2*0.2648421D-05*3000*299.70)-0.1673432D+00
                                               TCF =           4.595 div
                                     3,000 LBF =   +1002.050 div. From table    
                                                               1006.645 div. Correction for tare   

Difference between TCM and Tare Load Correction Using Computed Load Tables 

                                                TLC   =    1006.670 div.        
                                               TCM  =  -  1006.645 div.                       
                                        Difference =          0.025  div.




written by Henry Zumbrun



Posted at, March 14, 2016 12:00:00