Looking at our two “thought experiment” illustrations, we see that the only difference between
the two scenarios is the type of liquid filling that 3-foot region between the LR V and URV marks.
Therefore, the only difference between the transmitter’s pressures in those two conditions will be the difference in height multiplied by the difference in density. Not only is this an easy way for us to quickly calculate the necessary transmitter span, but it also is a way for us to check our previous work: we see that the difference between the LRV and URV pressures is indeed a difference of 11.52 inches water column just as this method predicts.