Basic operations - Weighing tubes

The XL20B Tare / Gross Weighing mode is designed for weighing large numbers of tube racks. In this mode of operation, the tare weight of tubes is obtained first, the tubes are then filled with a sample or compound, and then the tubes are weighed again to obtain the tube’s gross weight. The net weight of the sample or compound is determined from the tare and gross data. The tare, gross, and net weights are recorded in the output file. 

No work list is used in the Tare / Gross weighing mode. The tube racks are placed on the XL20B deck and the rack ID is scanned. From this point, the XL20B automatically generates a tare or gross weight output file for each rack (the filenames are the Rack ID# and with extensions .TWT or .GWT). 

1. Set the XL20B software to the Tare / Gross Weighing mode, if it is in work list Job mode. 
   
   You will need to restart the software for the change of mode to take effect.
2. Select the directory and data fields for the output file. 
   
   1. 1. 1. Select the Settings Menu
         2. Select Output file settings if you want to configure the output file in any way.
         3. Select Tare / Gross Weighing Mode Output Options.
3. Allow the balance to warm up for 30 minutes, if you have only just turned on the XL20B.
4. After a long period of inactivity, run the XL20B Scale Test Routine.
5. Click on the START button at the bottom left of the screen.

Tare weighing tubes

1. On the Weighing Options screen, check that Tare mode is selected.
   
2. Select which tubes are to be processed. Blue signifies a selected tube - the example above
   shows 96 tubes selected for processing. 
3. Click Ok to close the screen. 
4. The Tray setup screen is displayed.
   
5. Scan the deck position then the ID barcode for each rack, then place the rack on the XL20B deck, to tare weigh the empty tubes.
   
6. Once all racks are scanned and placed, click on the OK button. The XL20B will display the
   main status screen.
7. Press the Start button (bottom left of main processing screen) to begin the tare weighing
   process.
8. Tare weights are obtained and the XL20B generates the output file with Tare weight
   (RackID.TWT)
9. At this point you can optionally close the XL20B software e.g. if it will be some time before the racks will be ready for weighing again.
10. Remove the tube racks from the XL20B.
11. Fill the tubes with your sample compound, ready for gross weighing.

Gross weighing filled tubes

1. Restart the XL20B software if you had closed it.
2. Allow the balance to warm up for 30 minutes, if you have only just turned on the XL20B.
3. After a long period of inactivity, run the XL20B Scale Test Routine.
4. Click on the START button at the bottom left of the screen.
5. On the Weighing Options screen, select Gross weighing mode.
6. Select which tubes are to be processed. Blue signifies a selected tube. You must select the
   same tubes that you selected for the tare weighing. 

7.   Click Ok to close the screen. 

8.   The Tray setup screen is displayed.

9.   Scan the deck position then the ID barcode for each rack, then place the rack on the XL20B
deck, to gross weigh the full tubes.

10.   Scan the deck position then the ID barcode for each rack, then place the rack on the XL20B deck, to gross weigh the full tubes.

11.  Press the Start button (bottom left of main processing screen) to begin the gross weighing process.

12.   Tubes are weighed a second time, to obtain the gross weight.

13.   XL20B generates an output file (RACKID.GWT) that contains the tare and gross tube       weights and the net weight of the sample or compound. The gross weight file may also include the tube’s 2D bar code, if you had selected it in the output file settings.

Next article - Using the Reweighing function