Forum Index » Editor's Roundtable » A Survey of Water Hazards and Water Treatment Methods - Part 6: Ultra-Violet Light Methods


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Kevin Babione
(KBabione) - MLife

Locale: Pennsylvania
mUV Replacement on 11/03/2012 09:40:32 MDT Print View

If you can find it go ahead and email them to see what they might be able to do for you. I dropped my original one and it bounced off the floor of an AT shelter and broke the filament. I think they replaced it for $15 and it was clearly my clumsiness that broke it.

Jim Larkey
(jimlarkey) - MLife

Locale: NoCO
Re: Re: mUV Failure on 11/03/2012 12:01:28 MDT Print View

@James, stick w the SteriPEN.

Tjaard Breeuwer
(Tjaard) - MLife

Locale: Minnesota, USA
cold water with steripen? on 01/07/2013 13:11:56 MST Print View

Hi,

How does the Steripen do for winter camping?


Obviously the batteries will not work as long if cold. however Roger mentioned the uniot warms up during use, so if I keep the unit inside my clothes for storage, it should keep itself warm during use right, even in weather around 0F?

Is there any effect of water temperature on use of the unit? We would be getting water from underneath the ice, so it would be very close to freezing.

Ken Thompson
(kthompson) - MLife

Locale: Behind the Redwood Curtain
Re: cold water with steripen? on 01/07/2013 14:40:29 MST Print View

I've had zero issues with icy cold water.

David Thomas
(DavidinKenai) - MLife

Locale: North Woods. Far North.
Re: cold water with steripen? on 01/07/2013 15:39:20 MST Print View

Tjaard,

While disinfection by chlorine, bromine or iodine IS temperature dependent (lower temps require higher concentrations abd/or more time to be effective), in this case, chemical bonds aren't being broken/formed with other molecules (higher temp molecules are more reactive), but with UV photons.

The article details how UV photons makes thymine-thymine bonds in DNA rendering a virus, bacteria, etc, sterile - unable to reproduce/divide. That process is not very dependent on temperature.

Also, you're using lithium batteries (you pretty much have to in all the units), and they are much better at low temperatures than alkaline or nicads that we have more day-to-day experience with. That said, all batteries put out less current when (1) cold and (2) partially used. If you've got partially used batteries and they don't start/complete a cycle when cold, warm them up. My estimate - not a problem to 0C and 2/3s used, but I haven't tested that.

The batteries WILL, kind of, work "as long" at cold temps. The issue is if they can put out the 1 amp needed for the UV lamp. Even when cold, you'll get almost all the electrons out of a battery that you would at 20C, but maybe not at the current required by the device.

Edited to add my estimate for your original question: I suspect you are okay to 0F OR 2/3's used. i.e. it will probably work to 0F with new batteries. Or with largely drained batteries if warmed. But maybe not both. But if you're going to sterilize water in the next hour, it would be easy enough to put it in a shirt pocket under your jacket.

Edited to correct "breaks bonds" to "makes bonds". Thanks to Bill for catching that.

Edited by DavidinKenai on 01/08/2013 11:53:45 MST.

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
Re: cold water with steripen? on 01/07/2013 16:40:26 MST Print View

I think I remember reading the user manual that you don't want to treat water that has snow or ice in it, because the UV won't completely penetrate into the snow or ice where there could be organisms.

Then when that snow or ice melts, it will release the organisms, which can survive being frozen in water.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: cold water with steripen? on 01/07/2013 20:41:42 MST Print View

> you don't want to treat water that has snow or ice in it, because the UV won't
> completely penetrate
Absolutely!

A girl on my staff went to Bali with her husband and friends. They all got the usual tummy (and bowel) troubles - except for the girl. Why?
Well, they were drinking spirits with ice while sitting around the pool - except for the girl, who was expecting. She only drank Coke straight from a can. The ice - the water came from the kitchen tap. She had the last laugh.

Cheers

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: cold water with steripen? on 01/07/2013 20:42:39 MST Print View

What David wrote.

Cheers