Using Inova UV to purify water?

Would this work? Or does the UV have to be on a different wave lenght? I like the idea of having a light that would spot fake bills/ID's and purify my drinking water...

Regardless of the wavelength, this will almost definitely not work. One of the drawbacks of UV purification is that, even at very high power levels, the UV can only disinfect the water within about 1/2 inch of the light source. UV purification systems are specifically designed so that all the water volume is within the effective distance of the lamp and the flow is slow enough that there is sufficient exposure time to disinfect the water. No way would I trust the safety of my drinking water to anything not specifically intended for that purpose.

Inferno said:

Would this work? Or does the UV have to be on a different wave lenght? I like the idea of having a light that would spot fake bills/ID's and purify my drinking water...

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Apart from what DonShock said: The wavelength AND power output of UV LEDs is nowhere near of what you need in a germicidal UV lamp.

You also do not want to run around and shine a germicidal UV fluorescent tube at things - those are real eye killers.

-Connor

Inferno said:

Would this work?

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Uhh, you really think it's a good idea to consider improvised solutions to life-safety problems outside of a dire emergency? Stick to a purpose-built water purifier. The life you save will be your own.

you need to get down to UVC range or below 365 nanometers and deliver a large dose of UV to do the job.

currently LED's are not there yet. UV aquastar uses a UV florescent tube.

There are a lot of bacteria that are a lot tougher than you are. If you had a handheld light that would kill them you could do a lot of damage to yourself with it. Most of the biocontainment work areas that people use in research are set up for UV treatment to minimize bacteria in them. In most cases this is to keep bacteria in the air and and on the scientists from ruining experiments, not to protect people from the experiments. But those lights are way different than what is in a flashlight. The areas where they are in use are posted with the times the lights activate (they are usually on a timer to go on late at night) so that no one is in the way when they come on. Even much less powerful UV than those can give you a nasty sunburn in a short time and trash your eyes in less than that.

The cost of a good water purifier designed specifically for that task is nothing compared to the risks of doing it by improvisation. Just my opinion. Get something like this instead :
http://www.rei.com/online/store/Pro...ory_rn=4500461&vcat=REI_EXPERT_ADVICE_CAMPING

CM said:

The cost of a good water purifier designed specifically for that task is nothing compared to the risks of doing it by improvisation. Just my opinion. Get something like this instead :
http://www.rei.com/online/store/Pro...ory_rn=4500461&vcat=REI_EXPERT_ADVICE_CAMPING

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excellent filter but unfortunately does nothing for cryto.

I was one of the beta testers for UVaquastar and have used it extensively as my primary source of water in the back country for two weeks. did have MSR chrorine dioxide tabs as a back up.

you can imagine fear factor of getting sick in the middle of nowhere using a beta product. but UVaquastar came thru like champ! no one got sick.

the only way of making effectively making high energy UV is by using some kind of a discharge tube. Typically, they use a clear fluorescent lamp, which makes most of its emission at 254 nm. If you put your hand in front of it for a few seconds, your hand will smell funny from the action of the UV light.

The lamp looks as if its an ordinary lamp without the phosphor, but its not. It is made of a special type of glass that is transparent to shortwave UV. Standard glass is opaque to UVC.

I don't even think the inova would be good for spotting bills, unless you don't try to spot the 50 or 100 ones. Those need 360nm or lower IIRC.

IsaacHayes said:

I don't even think the inova would be good for spotting bills, unless you don't try to spot the 50 or 100 ones. Those need 360nm or lower IIRC.

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365nm works well for $100 bills, showing the correct red color.

Cheers,
Piers

CM said:

The cost of a good water purifier designed specifically for that task is nothing compared to the risks of doing it by improvisation. Just my opinion. Get something like this instead :
http://www.rei.com/online/store/ProductDisplay?storeId=8000&catalogId=40000008000&productId=47575397&parent_category_rn=4500461&vcat=REI_EXPERT_ADVICE_CAMPING

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Water purifiers are different than water filters, or water treatment tablets.

This is a pretty good discussion: http://www.hikerscorner.com/filterselector.html

magic79 said:

Water purifiers are different than water filters, or water treatment tablets.

This is a pretty good discussion: http://www.hikerscorner.com/filterselector.html

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an excellent article, naturally biased twards their own products. which are excellent! I'd like to get MSR Miox Water Purifier.

they really don't mention products like UV aquastar are available. it's main drawback is it's ad electronic device, which all are prone to failure.

According to "Chemistry of Water Treatment, 2nd Ed." by Faust and Aly, p. 489, 530:

- the water should be within around 120 mm from the light source (rule of thumb)
- the radiation should be around 240 to 295 nm
- a typical emplementation for 253.7 nm (low pressure murcury arc lamp): 750 gal/hr or less, 3/8" thickness, 4.2 sec contact time

Normal lethal doses are reported as (microwatt-seconds per square centimeter):

Escherichia coli: 360
Vaccinia virus: 30
Bacillus globiggi spores: 1300

Cryptosporidium parvo oocysts are of major concern in surface waters (lakes, streams, etc.). Work cited in Faust and Aly indicates that with a dose of 15,000 uW/s, a contact time of at least 150 minutes (2-1/2 hrs) was required to disinfect the water.

So:

In order to design an effective UV treatment unit you need to know the wavelenth(s) put out (already discussed) and the light intensity at all points in the water being irradiated. That second part is the hard one. Some waters are very clear and thus ammenable to UV disinfection; others are not.

Generally you have to filter surface water to get it clear enough to treat effectively. If you are filtering before UV disinfection, you might as well use a filter rated to remove crypto spores. This reduces the amount of time you have to irradiate to get safe water, since after filtration you are basically just deactivating viruses that made it through filtration.

I like filtration followed by UV. It doesn't create carcinogens like chlorine/iodine/other halogens can. Filtered and irradiated water tastes good, given decent raw (untreated) water.

The downside is that the it is tricky to do right, and it requires electricity.

For what it is worth, when I go out in the backcountry I filter and chlorinate with fresh household bleach. You get a higher carcinogen dose filling your lawn mower than you do drinking properly chlorinated water. But that's just me.

If you are actually going to build a UV water treatment device, you need to get ahold of someone who knows what they are doing. Treatment design is not so simple when starting from scratch.

Scott