Sitting here minding my own business (working on a powerpoint presentation ;) ) when from the kitchen, where SWMBO has just started lunch ...
BANG - - really explosive.
I rush through, and find SWMBO in a state of shock (it was *very* loud).
Cause ? (My first though was a bottle of home brew had popped)
Somehow the valve on the wheel of her wheelchair was weak, or damaged, and it just blew. 120psi dumped in a millisecond.
Looks like a trip to Halfrauds later ... with *both* wheels ;)
Jethro_uk scribbled...
Good job she wasn't in a race.
120psi seems rather high.
NT knows all about these things, of course.
It's a 24"x1" tube/tyre ... maximum rating is 140psi (although given the struggles I have getting it to 120 ....)
Turns out it's a 24"x1" tyre ... i.e. nothing that Halfords stock :(. Luckily a trip to a local bike shop turned up their last 24x1 tube. "Wrong" valve, and a "pick it up tomorrow" attitude if you wanted it fitted.
Back home, tube fitted (took just over a minute. Not bad since I haven't done it for 30 years), and already scoping Amazon/eBay for stock ...
Apparently it's because the tube gets so hot filling, the rubber by the valve weakens.
Do you have an issue with NT? It could have been his way of requesting helpful feedback.
I would have said 100psi is not untypical for a wheelchair, so 120 does sound a little high but then a manufacturer could easily recommend 120psi.
Or in our case, last weekend, the newly purchased can of Sadolin I'd put on the kitchen table had fired its lid into the ceiling, and spread a fine spray of black droplets everywhere. I assume it was cold in the ironmongers and it had warmed up in our kitchen enough to blow the lid off.
Perhaps you need to fill it from a high pressure cylinder, with a regulator to limit the maximum pressure, so that the air cools as it expands down to 120 psi.
Some people have indesgetion problems, you could hear my dads farts from the next room, bangers mash and lots of oinions.....
Our two manual chairs have tyres bearing the legend 'Max 60-70PSI'.
Bill
Well the only tube the shop had, has a presta (bike) type valve, as opposed to a schrader (car) type vale the original had.
Initially I was annoyed as (a) I wanted to replace *both* tubes, and (b) I don't like the idea of mismatched tubes (too much like amateur hour).
However on reflection, I think I prefer the presta. The actual neck of the valve is metal, so should be more resistant to pumping.
I gave up looking for any easy way to get a tyre to 120. So it's a once a month workout of bouncing up and down on the track pump for a few minutes ;)
I think the rule (counter intuitive as it may seem) is the smaller the tyre profile, the higher the pressure. These are 24"x1 tyres. The previous 26"x1.75 tyres SWMBO had were about 50-70 IIRC - you could fill them at a petrol station.
What's a tractor rear wheel pressure ?
often very low.
Jethro_uk scribbled...
Depends upon the load, tyre size, tractor...
My cheapo 12v tyre pump says it will go to 200 psi. It came from either Morrison's or Tesco.
Total load is tyre pressure time area of contact patch (or close, because the tyre isn't infinitely flexible). A narrower tyre has a smaller contact patch (unless it's being run a bit flat), so needs a higher pressure.
(Also the same pressure in a narrow tyre results in lower hoop stress, so you can run it at a higher pressure with the same strength construction.)
120psi is still fairly high for a 25mm bike tyre though:
So fill it slower so the air cools a bit.
An otion but where do you get the HP cylinder and how do you fill that. I guess you could hire a N2 one from BOC or whoever but that seems a bit overkill.
They all say some silly pressure but I'm not convinced they are really up to it. Is the flexi hose rated to that sort of pressure for a start or the cheapo crimped on ends?
i used to run my beach buggy tyres at around 14psi, the rears were only
255/85 x 15, so not as big as a tractors, but still a lot of square inches compared to most other tyres,My current push bike has 90 psi tyres, but very few square inches capacity, my older bike has 35 psi tyres, i get a much better ride on the newer bike with it's high pressure tyres amazingly.
i had air adjustable shock absorbers on the rear of my motorhome, tiny hose between the shockers and the valve in the drivers footwell, best pressure for the weight of the van was worked out to be 175psi, i'd take them upto 130 psi using my garage air compressor... would take a second or 2 and i could see the rear end rising as i put the air in,
Then i borrowed my brothers 12 volt compressor that said it was good for 200 or so psi,
It took 15 minutes to get from 130 to 160 psi... i had to give up then as the motor was smoking, i probably lost 50 psi removing the Schrader valve chuck, bloody stupid idea to use one of them for such a small volume of high pressure air,
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