24 replies to this topic Post Order

[Robrider]

Edman, on 08 February 2012 - 09:36 , said:

I'm not so sure this is the case. The canister gets very cold because the CO2 is converting from liquid to gas in a small volume. The overall temperature in tyre would drop, but I don't think it would be by more than 10°C or so. There might be some localised freezing by the valve but, unless it sets off a chain reaction, I think it would only cause a few balls to form.

Edit: It should also be fairly easy to test. Fill a spare tube with sealant, chuck it in the freezer overnight, install it in the tyre and pump it up with a floor pump (in case pressure has an effect). Spin it around, let it get to room temperature. Take it out and cut it open to look for balls.

I always thought the canister got cold do to the ideal gas law, temperature is proportional to pressure. In other words the rapid decrease in pressure causes a rapid decrease in temp. I also assumed that the tyre temp would increase because of the increasing pressure, but to a lesser extent due to the higher volume and lower final pressure.

I could be wrong though, I haven't thought it through fully.

[brad890]

WOW, I go to lectures and come back to people replying to this topic quite a bit.

Let me start my reply by saying I am NO chemical engineer or chemist ,I just decided to one day take a chance with making my own slime with some of the stuff i read on the web ( have had good results so far)

And i am in no way trying to bash the slime brand's that are out there etc.

Edman, on 08 February 2012 - 08:45 , said:

Completely wrong. Air is around 78% N2 and only around 0.04% CO2.

Yip you are right air is mainly N2 and very little CO2, from what I understand about basic chemistry when H20 and CO2 are mixed you end up with H2CO3 carbonic acid, which will cause a drop in pH, and from what I understand the liquid latex makes use of ammonia to stay liquid (please someone correct me if I'm wrong) which then leads to the latex coagulating making boogers. What effect the coldness of the CO2 gas on the slime has might also have an effect??? because when you make liquids colder it leads to them being more solid, If this has any catalytic reaction to booger formation i dont know (any chemists out there that would like to comment please?)

Help.Me., on 08 February 2012 - 09:03 , said:

The ingredients in your slime will it not have any effect on the rims or metal parts in a wheel spokes etc ?

I have no idea, the ingredients are pretty much the same as you would find in other slimes out there, if you give stans or joes a smell, one can smell there is added ammonia, what effect this has corrosively on aluminium i dont know (any metal engineers out there? that can comment)

So far from what I've seen, the slime doesnt seem to be affecting my rims? but then again havent been using it for years. Sawdust could you maybe comment?

Kranswurm, on 08 February 2012 - 09:11 , said:

I speak for myself but sealant is pretty cheap anyway.

A bottle of Stans will last me 9 months.
I use bombs to seal the tyre when refilling
I dont get balls???and after about 3 months I have to top up cause the tyre is dry from being used up in sealing all the thorn holes
Never have an issue.

well thats why I asked the question if people would be interested? everyone is entitled to their own opinion, if you compare R60 to R110 for a bottle of joes or stans then it is cheaper, but if you compare it to the above then not so much

THE BLOODY AGENT, on 08 February 2012 - 09:33 , said:

As they say in Dutch.... Goed koop is duur koop. Ill stick with my trusty old Stans

Well people will always have their own opinions an in my opinion its a good thing (excuse the pun? grammar natzi's?)
Its like saying which is better BMW, Audi or Merc? one will never come to an agreement, not saying that the stuff I'm wanting to mix will be better or worse, hence i will want to have some people test it before i'd start selling if there is interest

Edited by brad890, 08 February 2012 - 10:52 .

[Minion]

covie, on 08 February 2012 - 09:45 , said:

edman not sure why or how, but using bombs definitly causes my stans to coagulate. Everysingle time i have had to use a bomb i can be gaurunteed i have pretty peace of sealant coral knocking around in my tyres a week later. Just using the compressor or floorpump I have never had an issue.

I'm not disputing that it happens. I'm just wondering whether the cause is due to CO2 pH or whether it's due to the cooling effect from a bomb. The test I proposed would allow you to check whether cooling causes the balling by removing the influence of CO2.

Robrider, on 08 February 2012 - 09:47 , said:

I always thought the canister got cold do to the ideal gas law, temperature is proportional to pressure. In other words the rapid decrease in pressure causes a rapid decrease in temp. I also assumed that the tyre temp would increase because of the increasing pressure, but to a lesser extent due to the higher volume and lower final pressure.

I could be wrong though, I haven't thought it through fully.

Have a quick look at the canister specs here:
http://www.genuinein...-cartridge.html

If you do a quick PV = nRT calc it gives an internal pressure of about 42MPa for a 21cc canister containing 16g of ideal gas CO2 at 21°C. This is almost 10x the vapour pressure of CO2 at that temperature. There must be liquid in the canister.

Edited by Edman, 08 February 2012 - 10:53 .

[brad890]

brad890, on 08 February 2012 - 10:49 , said:

well thats why I asked the question if people would be interested? everyone is entitled to their own opinion, if you compare R60 to R110 for a bottle of joes or stans then it is cheaper, but if you compare it to the above then not so much

oops replied on the wring quote meant to be this one

davetapson, on 08 February 2012 - 09:22 , said:

Ryder (when I could get it at LBS!) was R40 for 250ml and was ammonia free.

Not sure if I'd go out of my way to pay R60 for 500ml - R10 saving for something I don't really know about, and will cost more than R10 in fuel / shipping to get?

Not saying it's a bad idea, but the value proposition doesn't work for me. Make it way cheaper, and the balance may change.

[Lucky Luke.]

sealant is too important to go for a cheap 'sort of works' option.

[brad890]

Lucky Luke., on 08 February 2012 - 10:59 , said:

sealant is too important to go for a cheap 'sort of works' option.

well thats why I'd like for more people to possibly test it first? to determine if it is crap or good? I've personally had results just as good as joes and better then stans (I seem to always get boogers with stans and thus flats out while riding, but thats just MY experience)

so on that note, anyone out there willing to give some of this stuff a test run?

Edited by brad890, 08 February 2012 - 11:04 .

[Kranswurm]

brad890, on 08 February 2012 - 11:03 , said:

well thats why I'd like for more people to possibly test it first? to determine if it is crap or good? I've personally had results just as good as joes and better then stans (I seem to always get boogers with stans and thus flats out while riding, but thats just MY experience)

so on that note, anyone out there willing to give some of this stuff a test run?

What happens if it delaminates the tyre.Will you cover it?

[brad890]

Kranswurm, on 08 February 2012 - 11:36 , said:

What happens if it delaminates the tyre.Will you cover it?

well i have no idea if it will cause delamination? I've heard from 2 bike stores now that they've had people with joes and kenda tires delaminate? anyone know what actually causes it?

but you bring up a valid point, thanks . I never thought about the whole delamination thing. hmmmm, this slime thing for other people idea, seems to be quite a finicky thing, with lots of variables and things that can go wrong, I think I'll have to go look into the delamination story and what possibly causes it.

[johannrissik]

brief hijack:

From http://www.genuinein..._about_co2.html

Generally, during actuation of CO2 gas delivery systems, if the gas is discharged with the cylinder in the 'up' position, only gas is dispelled from the cartridge. However, if the gas is discharged with the cylinder in the 'down' position, and with gravity affecting the liquid CO2, along with the gas being dispelled, some liquid CO2 is also ejected. This liquid CO2 instantly turns to dry ice, sublimating quickly into a gaseous state. This property of actuation is useful in some applications where increased gas pressure is desired.

Brief hijack off.

With the price of good tyres and wheelsets, the cost of sealant used is not such a big deal. What percentage of your "bike-spend" is on sealant?

While the jury may be out on the ammonia story, I'd hesitate to save a few ront and possibly jeopardise my fancy ZTr wheelset and those Maxxis tyres.

That said, in 6 years of tubeless, I have had one tyre delaminate (Bontrager, non UST) and that could have been due to multiple doring stabs, or just the fact that I was using it outside of it's design parameters. Can't say for sure it was the Stans in the tyre. And absolutely no visible damage to WTB, DT Swiss or ZTR rims.

I have used a wide variety of sealants in an even wider range of combinations on a range of tyres (mine and other people's) and the only problems have been sidewall cuts and valves failing.