Always fill up on a cold day

[silentC]

An odd thing happened earlier this week. On the weekend, I filled the car up with petrol. It's an old Mazda Capella and the filler nozzle on the new unleaded pumps doesn't fit properly, so it's easy to overfill. Anyway, I probably put a bit much in this time, but no drama, and I drove away.

Is has been bloody cold lately but on Tuesday we had an unusually hot day. I was sitting in my office when the landlord's daughter came in and told me something was dripping from the car and it smelled like petrol. I went out, and sure enough, there was petrol dripping from just under the rear guard next to the filler. My first thought was a leak, so I popped the flap and opened the filler and out came about a cup full of petrol. Well that's weird I thought, because I'd done a few K's since filling it up, so how could that happen?

It seems that what has happened is that the petrol has expanded, as it does, because it was freezing the day I filled up and hot on this day. I had managed to fit more petrol in there than the tank could hold at the warmer temp, even though I had used a up a bit of it in the meantime.

So the moral to the story is that if you fill up on a cold day, you get more for the same price, because the mass to volume ratio goes up the colder it is. But make sure you don't overfill, or some of the profit runs down the drain.

I suppose this is factored into the price but it's worth taking advantage of when fuel is currently around $1.45 a litre :eek:

[Cliff Rogers]

Hmmmmmmmm............... Warning: SCIENTIFIC CONTENT. Using that same line of thought, your tank should have shrunk on the cold day & expanded on the warm day.

I find that if I can get a servo where the concrete pad leans away from the pump a bit, I can get a couple of litres more into the tank & more still if I park nose down as well as tilted away from the pump..

I reckon it was most likely a slight tilt on the servo driveway & a slight tilt on your own driveway the opposite direction.

But, don't let this get in the way of a good story and DON'T RUN OUT OF FUEL WAITING FOR A CLOD DAY TO FILL UP.

[silentC]

OK, there are a couple of problems with your suggestion:

1. Petrol expands and contracts at a much greater rate than steel at normal temperatures. Have you ever opened the lid on your lawn mower fuel tin when it's been in the sun? What's that hissing sound?

2. I filled up on the weekend and the phenomenon I have noted took place on Tuesday, so why didn't it happen on Monday? And there was less fuel in the tank on Tues too. Unless someone sneakily topped it up. But at $1.45 per litre, who would be silly enough?

Keep trying though

[Wongo]

Top story Silent.

Hmm, what if I buy a lot of petrol in winter and sell it in summer??.... bingo

Anyone interested.

Does it mean you get more beer from a schooner in winter?

[Cliff Rogers]

OK, there are a couple of problems with your suggestion:

1. Petrol expands and contracts at a much greater rate than steel at normal temperatures. Have you ever opened the lid on your lawn mower fuel tin when it's been in the sun? What's that hissing sound?

2. I filled up on the weekend and the phenomenon I have noted took place on Tuesday, so why didn't it happen on Monday?

Keep trying though

1. Petrol gives of gas when hot so it pressurises the can.

2. If Monday was cold, see answer 1.

3. you could also be right but I fell asleep trying to get to the answer in this waffle....
http://www.publications.parliament.u...81/3032602.htm

[Wongo]

Or sell hot beer cos' you can sell more. What is that mass to volume thing again?

[Cliff Rogers]

Top story Silent.

Hmm, what if I buy a lot of petrol in winter and sell it in summer??.... bingo

Anyone interested.

Does it mean you get more beer from a schooner in winter?

http://www.publications.parliament.u...81/3032602.htm

[Wongo]

I hate reading Cliff.

[Cliff Rogers]

I hate reading Cliff.

Sook, I'll pick the eyes out of it for you....

Every year, consumers pay for about 200 million more pints of beer and cider than they receive. (Froth)

(fuel)....it is delivered from some refineries warm. By the time it gets to the garage forecourt, it has contracted. Therefore, the petrol retailer actually has less product to sell to the consumer....

.....we are looking at a device called "standard temperature accounting", which basically corrects the volume of petrol sold to the standard temperature, so that you have the equivalent volume bought at 15º, which is the temperature at which the retailer would sell.....

Enough?

[bitingmidge]

I think it explains why you want to wee more after drinking cold beer too.

Obviously your wee-guage measures the volume to be disposed of and sends signals to the overflow bit.

The amount is choofed out, and all seems to be well, but the bit remaining is cold, expands as the body heats it up and well the cap wants to overflow.

Actually there may be something in Cliff's theory too. I've seen quite a few people standing on a slant after drinking a few beers, perhaps if they were a bit more level, they'd only have to go once?

Interesting stuff, this science stuff.

P (Dr Midge to his mates.)

[Wongo]

Bugger!! I just had a lot of cold pudding....

[silentC]

Petrol gives of gas when hot so it pressurises the can

You silly moo, that's what the act of expansion is all about! The molecules in the liquid get further apart until it becomes a gas. They are the same molecules in a different state. Dear oh dear. Tsk

In fact if petrol didn't exand and contract at a high rate, an engine wouldn't work.

Anyways, I found a link to a paper on a university site and it says I'm right, so nyah nyah.

[craigb]

The amount is choofed out, and all seems to be well, but the bit remaining is cold, expands as the body heats it up and well the cap wants to overflow.

Yes but I've noticed that the speed of this process increases once the initial seal is broken. So that the time between subsequent "overflows" reduces in a non-linear fashion.

Why is this? :confused:

[bitingmidge]

You silly moo, that's what the act of expansion is all about! The molecules in the liquid get further apart until it becomes a gas. They are the same molecules in a different state. Dear oh dear. Tsk

And beer?

P
:confused:

[Wongo]

Your right again Silent.

Funny enough I too have done a similar experiment while in university. I took a photo of a glass of beer in summer and took another one in winter….


I failed that year of course.