On Sep 16, 7:42*am, dgk wrote:
On Wed, 15 Sep 2010 21:55:19 -0500, John Thompson



wrote:
On 2010-09-15, dgk wrote:

I have one of those $25 air horns - this kind of thing:

http://www.nycewheels.com/air-zound-horn.html

It is very useful for commuting, capable of easily penetrating the
headphones of joggers and such. However, I never used it in winter
before because it was too much to take off the bike when parking
outside at the office. Various lights, batteries, etc.

Now I will be able to bring the new bike into the building. So, while
I could continue to use it, I'm concerned about the effect of cold on
the bottle and its contents (air). Surely it not last as long, but
will the bottle get brittle and explode? I think it is best to not
find out the hard way.

I have no direct experience with air horns, but in general lower
temperature will lower the pressure in the reservoir, which will
probably cause it to become ineffective sooner (although returning it to
a higher temperature will restore it).

The reservoir is likely metal, and the cold will not affect it. In fact,
the lower pressure in cold temperatures will put it under less stress
than it would otherwise suffer. *

Nope, the resevoir is a plastic bottle, likely a bit thicker than a
standard soda bottle. If it were metal I wouldn't be too concerned,
but being plastic...

Here's a better pictu

http://www.amazon.com/Delta-Airzound.../dp/B000ACAMJC

I've noted before how nice they are to lower the price to below that
eligible for free shipping.

On Myth Busters, the pumped up a 2 liter bottle until it exploded at
150 PSI, so I have no concerns about using regular 20/24 oz soda
bottles. The only thing I could think of is moisture forming ice in
the hose or horn. Bringing it inside should melt it before the next
trip. Perhaps a little calcium chloride in the bottle would absorb
the moisture.