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Siemens Industry Online Support
Siemens AG
Entry type: FAQ Entry ID: 109762400, Entry date: 11/21/2018
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Appropriate test mass for belt scale calibration

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Problem/FAQ: How do I select an appropriate test mass for calibrating my belt scale?
 

Solution

The appropriate test mass can be selected by the Belt Scale Sizing Tool or can be calculated by hand.  Either way we first need to have some basic data about the belt scale application:

  • Design flowrate

  • design speed

  • and idler spacing as the bare minimum. 

  

First, calculate the Design load in kg/m or lbs/ft.  The design load equals the Design rate divided by the Design speed. (L=R/S)


For example, let’s use 500 t/h rate, 2.0 m/s speed, and 0.9 m idler spacing.
So the design load is:


500 tonnes/hour  *  1000 kg/tonne  / 2.0 meter/second  / 3600 seconds/hour 

=  69.44 kg/meter


Second, determine at what percentage of design load you wish to calibrate.  For our belt scales that have no moving parts, pivots, torque tubes, or trunnions, we can safely and linearly calibrate between 20 and 60% of design load.  For most non-Siemens scales, you will need to calibrate between 60 and 80% of design.

 

For example, let’s use 40%.

69.44 kg/m * 40%  =  27.78 kg/m

 
Next, we will determine the test mass in kgs or lbs. To calculate, multiply the desired load by the idler spacing.


For our example;

27.78 kg/meter  *  0.9 meters  =  25.0 kg

 
Finally, we select the weights. Take a look at our catalogue offerings and choose the weights and quantity required to get the closest to our target.

 
For our example of 25.0 kg, we would probable choose quantity 3 of the J weight, 18 lb/8.2kg for an approximate mass of 24.6 kg.

There are different test weight options for some belt scale models and we also offer the MWL (weight lifter) option as well.