[AuRavelling79]

A question I was asked by a customers Health and Safety rep:-

Is the freezing point of pure water higher or lower than normal tap water?
(His concern was water freezing on footpaths beneath windows around their site.)

I don't know, do you?

[Duke]

no I don't...but I'd imagine it freezes more readily....the thinking behind this is that salt water takes longer to freeze than fresh water...therefore...water with no impurities in it.....

[Craig_Mawlam]

Ordinarily the freezing point of pure water is lower than tap water. Ice crystals form on mineral deposits, very pure water has no mineral content. However, once your pure water has been used to clean the windows, run down over masonary and puddled on the ground it will no longer be pure and will freeze just the same. In practical terms if its that cold you probably will not be using a WFP unless you have a hot water Thermo-pure system simply because the water will freeze in the hoses. If you are concerned and to allay your customers concerns too, carry some rock salt in a sealed container and spread it on at risk pathways first.

Rgds
Craig Mawlam

[Ian_Giles]

Watching the christmas lectures this year educated me in regards to the freezing of pure water, water purified to the n'th degree doesn't freeze until something like -20 .
The stuff we produce will freeze before that point of course, and as Craig says, the water is contaminated by the time it hits the deck anyway.
I did an experiment with pure water and tap water, I filled identical shot glasses and stuck em in the freezer
Wasn't a lot of differrence in the time it took either to freeze, but the pattern in the ice was remarkably different............an absolutely useless fact I know But after dipping the glass in a little warm water I did have a couple of nice shaped ice cubes to go in my vodka though

Ian

[Craig_Mawlam]

Ian,

If you want to get a result from your test re-circulate 0 TDS water through brand new virgin resin 10 times or so so that it becomes really pure then try it again, your shot glass has to be perfectly clean also so soak that 2-3 times in pure water for an hour or so. The slighest impurity will have an effect on the outcome.

Rgds
Craig

[AuRavelling79]

So if I have a water butt of pure water (for storage) under my car port or in my back garden is it as likely to freeze as tap water or rain water would?

The reason I ask is that I was thinking of having my R/O unit in the utility room off the kitchen and then feeding the pure water through the wall to a water butt, where I could draw off 25 litre drums for my trolley system.

I live just north of Bristol so we don't often get severe frosts below about -2 or 3.

[Duke]

I'd say yes. If you intend to store water like that...it needs to be undercover, in at least some sort of heated area..(or heated itself)...a block of ice is no good to you....(and ok, so it wouldn't freeze solid...if it was that cold, we'd all be off work...but still)

[Steve_Richardson]

I keep a water butt outside and when it was filled to the briwm the other week when it was really freezing, it was still ok. At the most about 1/2 inch was maybe frozen on the top but I could still draw water from the tap at the bottom.

The 25L containers that I had full outside were frozen to about 1/4 of the way down.  During sue they would thaw out enought to enable me to sue most of the 25L but as I was wheeling my trolley around the ice and water sloshed about and sounded very much like Santas sleigh bells!!

But, I always bring my filters inside if I think it may freeze overnight as I guess the water in them would freeze, expand and possibly break the glass, and I also heard the freezing can damage the RO.

Cheers
Steve

[AuRavelling79]

Steve, what area of britain are you in, I only ask because of temperature variation:-

you know what I mean

N.E. Scotland often - 10 at night     
Devon/Cornwall never below freezing (except on the moors)
 

[Duke]

I grew up in Cornwall....believe me.. it does freeze on occasion...and I've been snowed in (in Helston)....most people would be right to assume that, as alot of the 'known' places are coastal...and sea air stops the freeze, it wont......but inland...it can be as cold as anywhere....I know,I spent my childhood on a farm there...it get's f***ing cold.