A PopEyed Visual Guide to Liquid Flow Rates

Easily estimate the flow rates of liquids! Rob shows you how

Only marginally concerned with the actual utility of such a project, I recently embarked upon a quest to record and illustrate the rate of water flows. Would you like to measure the rate of a dripping faucet, but lack the sophisticated equipment required? Do not despair! Armed with a gallon jug and a stopwatch, I have prepared an easy-to-use water-flow estimation guide.

Fast Drip

There is no way to jazz this one up, so let's just get it out of the way. I measured a "one drop per second" flow and it worked out to 0.3 gallons per hour.Rob Cockerham

Very Thin Stream

If you slowly increase the flow, a fast drip becomes a steady stream. The smallest stream I could achieve was this one, about 1/16th of an inch wide. It was 1.1 gallons per hour.Rob Cockerham

Toyota Corolla Fuel Injector

An easy example is freeway driving in a 2009 Corolla. 60 miles per hour at 30 miles per gallon equals 2 gallons of gas injected per hour. This was easy to measure but difficult to photograph.Rob Cockerham

Formula 409 Spray Bottle

Steadily pumping a bottle of spray cleaner pushed 16 ounces through in 3 and a half minutes, which works out to 2 gallons per hour. I consider spraying 409 a good way to visualize how much fuel a 2,700-pound Toyota Corolla uses cruising along on the freeway. I think that is pretty incredible. I can only imagine how little gasoline a car uses while idling. Most cars have four fuel-injecting sprayers, so each individual injector would be spewing a quarter of this volume.Rob Cockerham

Drip Coffee Maker

Our Mr. Coffee produces coffee in a tiny stream: 56 ounces in 12 minutes, or 2.2 gallons per hour. Coincidentally, this is the same rate at which I drink it. Maybe it would be faster if you put the whole rig inside a centrifuge, but I can't figure out how keep the power cord from getting tangled.Rob Cockerham

Thin Stream

A slightly wider stream (1/8th inch) filled a gallon jug in 5 minutes, or 12 gallons per hour. This does not appear to be 12 times larger than the very thin stream, but it is.Rob Cockerham

Heavy Stream

Our aerated kitchen faucet delivers a respectable 7/16th inch flow, filling a gallon jug in 40 seconds. This is 90 gallons per hour.Rob Cockerham

Shower Head

This is not supposed to be a low-flow shower head, but the output was notably stingy. It filled a 5-gallon bucket in 2 minutes and 50 seconds, or 106 gallons per hour.Rob Cockerham

Soda Fountain

Inside the AM/PM mini-mart, the extremely aerated Diet Coke dispenser delivers 44 ounces in 9.5 seconds, or 130 gallons per hour. When science finally delivers a waxed paper cup that can hold a gallon and fit into an automobile's cup holder, these soda dispensers will be ready.Rob Cockerham

Gallon Jug Dump-Out

Dumping out a one-gallon milk jug, inverted and allowing lots of glug: 17.8 seconds, or 272 gallons per hour.Rob Cockerham

ARCO Gas Pump

Gas pumps dispense thousands of gallons of explosive liquid quickly and accurately. They are pretty impressive machines that are easy to take for granted. The pump I tested delivered a gallon in 8.7 seconds, or 420 gallons per hour. At this rate, a single gas pump could keep 200 cars fueled and running continuously.Rob Cockerham

Garden Hose

Thanks to detailed tables crafted by engineer-farmers, it is possible to estimate the rate of water flow just by measuring the interior diameter of the hose and the distance it jets out horizontally. I had already prepared my 5-gallon graduated bucket, so I ignored those tables and went ahead with my timing plans. This full-speed garden hose shot water about a meter before it hit the ground. This was fast enough to fill the bucket in 33 seconds, or 545 gallons per hour.Rob Cockerham

Five-Gallon Bucket Dump-Out

What took 33 seconds to fill takes 3.2 seconds to empty. This deluge is pretty impressive, and works out to 5,625 gallons per hour. Remember this the next time you are battling a circus fire with a bucket brigade.Rob Cockerham

Summary

There you have it: everything you need to become an expert in visual water flow estimation. I suggest you next try mastering a musical instrument of some kind.Rob Cockerham