Metering equipment and instruments

It's up to you to figure out how you'd like to test the flow and flush rates, but the way that I've seen it done in the past is much more low-tech than you're describing. We've simply disconnected the flushometers and used a bucket to catch the water from each flush. For sinks, we'll run the water for 15 seconds and then measure how much is collected and multiple by 2 to get the amount dispensed in 30 seconds. In an ideal exercise, each fixture should be tested 3 times, the results recorded and then averaged to get the average flow/flush rate per fixture. The results for an entire fixture family (i.e. urinals) may then be aggregated to get the average flow/flush rate for the entire facility. At least 20% of the number of fixtures in each fixture family should be tested and, to account for varying water pressure in upper floors of the facility, you should start your testing on the ground floor and work your way up.