Extract specific row copies from multiple worksheets in Excel 2007 workbook

I have an Excel 2007 workbook containing 12 worksheets. 9 of these worksheets (named Unit 1-9) are of the same structure, being raw data from hand scanners. These 9 worksheets have 12 columns and can each have up to 3,000 rows.
I want to create a further worksheet in this workbook that contains copies of the rows from all the 9 sheets that have the numbers 51-54 recorded in Col B. I would preferably like to have all the 51's together consecutively, then the 52's, 53's and the 54's. I would like the sum of each of these section copies Cols K and L totalled separately.
It would take too long to put all the rows from the 9 sheets together in one sheet. I am looking for a faster way.

Many thanks in advance.