Faster Than a Speeding Gas Pump

April 27, 2008 3:46 PM

Does it take longer to fill up a gas tank when the price goes up by 25%?

And..... if the price of gas goes up by X, is there an equal increase in the speed at which the digital price is displayed? Lastly is there a limit to how fast the digital price can be displayed?

posted by Xurando to travel & transportation (13 comments total)

No.
posted by dhammond at 3:50 PM on April 27, 2008

No, no, and no. What on earth makes you think otherwise?
posted by xil at 3:51 PM on April 27, 2008

Probably because it feels like FOREVER as the pennies keep spinning upwards on the pump display.
posted by jerseygirl at 3:55 PM on April 27, 2008

If you pre-pay and buy $10 worth of gas, it would take less time.
posted by Frank Grimes at 3:57 PM on April 27, 2008 [1 favorite has favorites]

I think i see what you're asking, but I don't think delays in the price display would ever slow down the speed of gas actually coming into your car.

I would imagine that the display already does not display every single penny:

4.62
4.63
4.64

but instead updates the price it's showing every certain unit of time, whether that be a second, tenth of a second, whatever. So if the price goes up, that just means the price jumps by bigger increments on each update.

Failing that, I would think the price display would just lag a bit behind "real time," and catch up within a second of you stopping pumping. This is all speculation, though.
posted by drjimmy11 at 4:06 PM on April 27, 2008

to answer the second part, there is always a limit to how fast electronics can accomplish tasks. But in this case the more relevant limit is almost certainly how fast gas can be inserted into your tank in a safe manner.
posted by drjimmy11 at 4:08 PM on April 27, 2008

This is crazy talk, really, really crazy talk. The pump pumps at its rate and it is not tied to price or any other thing, other than how hard you pull on the pump lever.
posted by caddis at 5:36 PM on April 27, 2008 [1 favorite has favorites]

The display is driven by the amount a gas you've pumped, which is measured by a flow meter. There are many ways to measure flow but gas pumps typically used the turbine variety. Before digital displays, there were reels of digits mechanically driven by the flow meter.

Now, of course, there's a microcontroller in the mix, integrating the data from the flow meter and updating the display. There's little chance you could pump so fast that the computer couldn't keep up. However, depending on the algorithm in the firmware, the sampling rate might be slow enough to cause the display to hop over a value here and there (as drjimmy suggested).
posted by king walnut at 5:51 PM on April 27, 2008

Following what others have said... The gas comes out at the same speed. But as 1 gallon of gas costs more, and the display is presumably updated with each 1-cent increase, the cost will go up more quickly, ergo the display will update more frequently.
posted by fogster at 5:56 PM on April 27, 2008

The last time that gas prices spiked I heard that station owners were slowing down the pump as a sort of convenience so you wouldn't accidentally pump 30 dollars worth of gas in 3 minutes when you meant to pump 10 dollars worth. The question is can station owners even change the pump speed?

Maybe they can't but I am also the kind of person who notices slight changes in things and I support the OP asking this question.

Also, when times are tough station owners might not change the filters as often which will slow the pump speed down. Our local gas station is really seeing some hard times because everyone has really cut down on gas buying in my neighborhood. I bet he's not changing the filters this month.
posted by cda at 6:18 PM on April 27, 2008 [1 favorite has favorites]

I had it on good authority that some stations will re-calibrate the pumping speed of the pump when prices are high in order to reduce the chance of people pumping more gas than they could afford or intended to.
posted by sourwookie at 7:09 PM on April 27, 2008 [1 favorite has favorites]

One time when I was pumping gas, the pump was miserably slow. Like one cent per second slow. At full blast. I asked the people at the desk, and they said they accidentally slowed it down too much. They apparently slowed it down as the price goes up. Not saying it's universal, just that they definitely did it there.
posted by General Malaise at 10:31 PM on April 27, 2008

you know what Einstein is supposed to have said about relativity: "sit on a hot stove for a second and it feels like an hour, stare at a beautiful woman for an hour..."
posted by dougiedd at 11:51 PM on April 27, 2008