On 07/22/2017 08:40 PM, Mad Roger wrote:
For a typical 20-gallon fill, how many gallons off can reality be, plus or
minus from the indicated reading on the pumpmeter?

http://www.npr.org/templates/story/s...toryId=5304258

The article talks about Washington but most states have a similar
protocol. Pump 5 gallons of gas. 1 gallon is 231 cubic inches, so that
is 1155 cubic inches. The volume must be within 6 cubic inches or
roughly 0.5%. I'll let you do the math for 20 gallons.

http://billingsgazette.com/news/stat...5351736b4.html

Montana uses the same test. Note that he estimates 2 to 3% of the pumps
fail and have to be repaired and also says with normal wear the pumps
tend to dispense more than stated but some may dispense less. That's
where averaging over a number of tanks comes in unless you fill up at
the same pump at the same station every time. I certainly don't.