UV Light to Kill W/C Bacteria

[CoolROD]

1 Angstrom = .1 nm

[bigben2k]

Originally posted by CoolROD
1 Angstrom = .1 nm

The unit in question is called the "Angstrom 2537 Sterilizer".

So that's 253.7 nm, which isn't too far off of the 265nm wavelength that Al Kaseltzer linked us to.

According to this pic:
UV-A is in the 360 nm range, UB-B is in the 305, and UV-C is in 275, or something like that... (never mind the colored lines)

[CoolROD]

bigben2k: The unit in question is called the "Angstrom 2537 Sterilizer".

That seems like a real winner. The units are also sized appropriately for most of our flow rates. I definately want an inline unit. I am thinking 8W or 15W, mabye CD-400952 to save $50

You mentioned neon earlier -you are probably right. This looks like some kind of neon bulb with 2 pins at each end. The bulb is clear with no indication of phosphorus coating. Anyway -just curious.

[bigben2k]

Yes. the neon is mercury based, which as I remember it, is required to produce those kinds of wavelengths.

[CoolROD]

I might be able to get the 4 watt unit in my case...

4 Watt: 2.3/4" Dia. x 8" Long w/ 5/8" Dia. barbs
8 Watt: 2.3/4" Dia. x 14" Long w/ 5/8" Dia. barbs
15 Watt: ??? Dia x 21.1/4" Long w/ 1" Dia. barbs
25 Watt: 4" Dia. x 21.1/4" Long w/ 1" Dia. barbs
30 Watt: ??? Dia. x ??? Long w/ 1" Dia. barbs


Looking at the measurements I don't think there would be any problem moving more water through it than the rated 20 GPH. But with such a low flow rating my water might not get enough UV soak time to be beneficial. Any thoughts???

[Pheonix]

Yes but your water will be coming around again quite quickly, the water in a pond would take alot longer to go around

[CoolROD]

Does anyone know the continuous exposure time required to kill microbes and algae found in a W/C system?

[bigben2k]

Originally posted by CoolROD
Does anyone know the continuous exposure time required to kill microbes and algae found in a W/C system?

No clue, but your best bet would be to respect the max flowrate ratings.
Power / max gph / Max tank size (g)
4 W / 120 / 75
8 W / 180 / 150
15 W / 450 / 300
30 W / 750 / 500

This is going to depend on your setup.

[Althornin]

Originally posted by bigben2k
No clue, but your best bet would be to respect the max flowrate ratings.
Power / max gph / Max tank size (g)
4 W / 120 / 75
8 W / 180 / 150
15 W / 450 / 300
30 W / 750 / 500

This is going to depend on your setup.

I dunno, i bet tank size has a ton to do with it.
These are what, 1/2" ID?
Do the flow calcs and figure out exposure time.
But considering that each of those has said exposure occuring slightly more often than once per hour (flowrate is some higher than tank size) and we are tlaking a watercooling system with less than 1 gallow total (most systems out there), then for even the 4W system, we are talkiing about 75 times the overall exposure time for each "bit" of water. Thats gotta mean something in terms of sterilization.

[CoolROD]

I have done the flow calcs and show about .2 ft/s through the light. (Do I need to prove this?? :shrug: ) I need a recommended lethal exposure time of the pests to gauge the effectiveness of this light. I just want to know how many times the spores, or whatever, will need to pass through.

[CoolROD]

so - i am talking 2.4 inch/sec. and mabye 2s exposure time per pass with the short 4W unit. (Mabye 5" useful length)

This was figured at 150 GPH (or 2.5 GPH), 30 Deg. C Water.
I can reach this flow number as I might plumb the light as a kidney loop or use it in a machine tool

Actual flow through my system is much slower and I can easily adjust for that -should I figure out how to get this in my case and into my primary loop. Thus the (exposure time) / pass will be even higher.

I am looking for the magic figures on UV lethality vs. Algae & Bacteria. -Then I am going to need to figure average intensity...

[CoolROD]

I am guessing the light has mabye 3.5 to 4 in^2 area of water column.

[Althornin]

Aha!
Found some stuff:
From here:

where "A" refernces lethality for 270nm light

This source appears to be quite fantastic, offering up this jewel:

UVGI inactivates pathogens according to the standard decay equation

S = exp(-kIt)
In this equation S represents the fraction of the original population that survives exposure at time t, and I represents the UVGI intensity. The rate constant k has been determined experimentally for a number of bacteria, viruses and spores, at different power levels. Summarized below are many of the known rate constants for the indicated pathogens. Since many researchers have obtained values that differ, they have all been included. The source documents may be found in the references.

and an accompanying chart, where k is listed for many differnet pathogens.

NONE of the "k" (rate constant) values go above .002503 in WATER (from listed bacteria/virii, etc).

[Althornin]

Now, i'm too lazy to do the actual math (i just got my BS in mathematics, after all) but with the power output of the light, one can easily calculate survivability per GPH (flow).

The question then arises, how much survivability do we need? because the water is recycled through this system, does that mean we can assume that each cycle is a new "kill off"? Or that only the resistant bacteria remain?

I guess we will be answered once someone computes the lethality for the flow rates they describe. (by "they", i mean the producers of these sterilizing devices)

[CoolROD]

Althornin -This is some great stuff! -You even hit our target wavelength. Thank you for the great research -and lightning fast too.

I will gladly attempt the figures for various flow rates and corresponding exposure times. However this will have to wait a few days b/c I have to go earn my pay in another state. If I am not beaten to it...

Does anyone have figures for algae resistance to UV?

Are there any other nasties we are ignoring?

[CoolROD]

And we need to answer Al's question "how much do we need" This might fall into place with the new data on lethality, but will definately be a topic for discussion.

[CoolROD]

Here is a really good link for this topic. It gives the germicidal light energy required to kill common microorganisms.

http://www.debary.de/eng/pdf/aquagb02.pdf

I have also saved this file in case it gets lost...

Quotes from this source:

Approximately 30% of the input energy provided to a germicidal lamp is converted into UV light at 2537 Angstroms

The best operating temperature of the lamp is around 40 C

[Althornin]

according to my readings on the subject:

The question then arises, how much survivability do we need? because the water is recycled through this system, does that mean we can assume that each cycle is a new "kill off"? Or that only the resistant bacteria remain?

has been answered.
Each cycle is a new kill off.


Ok, i had a huge math post typed up, but i figured, SCREW THAT - So i made some sweeeeeet ass excel file to do all the math for us.

Please look over my maths and look for any errors.
If you have any questions about what i am doing, ASK! I make mistakes, so i'd like to know what you guys think.

Anyways, let my give the results here:
For a system, using the 4 watt unit, with flow rates of 10 liters/minute, one liter total system volume, assuming 30% efficiency as per CoolRods recent post, we get:

% kill Off per Hour:
66.47220214

%kill Off per Day:
100

Now, given the max the Sterilizer is rated for, being 120 GPH and tank of 75 gallons, we get: 7.6 l/min and a 284 liter tank, we get:

% kill Off per Hour:
0.384047722

%kill Off per Day:
8.821302748

Now, this doesnt look so hot, eh?
Yet, manufacturer says this amount will be enough to "clarify" the water - those max values were not for sterilization, but for "Clarification".


Ah yes, these results also assume no growth during said time, so the real figures will be less. hwoever, as long as kill off is greater than growth, we win....
And, play with the file - tank size is a HUGE contributor to changes in kill off.

The EXCEL file:
UV Kill Off

[CoolROD]

AL -Great Work!...and sorry for the late response...

I immediately started using your spreadsheet to juggle numbers. With my new Johnson pump from bigben2k's thread -I should be able to hit 10 L / min with my setup, though I really can't see why flow rate would affect the UV system...It seems like all we need to know is volume and watts.

If we assume that all of the water will go through the clarifier sooner or later, then can't we spread our volume into a thin sheet and divide the effective watts over this area?

NOTE: This is exactly how Althornin's spreadsheet behaves -play with it!

Al. -don't hesitate to post math here, especially if you already had it typed up...I know that I always enjoy an education...

Also, it would be my bet that a slow flow rate will result in greater efficiency of the UV light kills -much like small doses of penicillin vs. heavier -more complete- doses. Then there is the question of developed tolerance...

[CoolROD]

The Tetratec UV5 Clarifier is a 5-Watt unit that is fairly compact (scaling from the hose barbs) and touts 300 gph flow rates. It comes with universal-cut-to-fit, 1/2", or 3/4" hose barbs -depending on whose ad you read...or apparently depends on who you buy the unit from...

The "Tetratec UV5 Clarifier" looked promising as a Reservoir / Air Trap -but the inlet would probably be too high for this purpose.

Replacement bulbs are cheaper for the Angstrom 2537 Sterilizers than the Tetratec UV5 Clarifier and bulb life is reduced by frequent start / stops. I think we will only have to use these weekly, or possibly less often. And for the really High Flow people -you could plumb this as a "kidney loop" by only bypassing part of your water through it.

Here is a thought: Why not sterilize the water / components before putting a system together? Obviously this is not real practical.

Also, if we use distilled water -Where are these microorganisms coming from? Airborne?

[h4rm0nix]

Also, if we use distilled water -Where are these microorganisms coming from? Airborne?


I think there coming from the deep dark places in our WC setups...the rad.


H

[Althornin]

Originally posted by CoolROD
I can't see why flow rate would affect the UV system...It seems like all we need to know is volume and watts.

If we assume that all of the water will go through the clarifier sooner or later, then can't we spread our volume into a thin sheet and divide the effective watts over this area?

NOTE: This is exactly how Althornin's spreadsheet behaves -play with it!

Al. -don't hesitate to post math here, especially if you already had it typed up...I know that I always enjoy an education...

Also, it would be my bet that a slow flow rate will result in greater efficiency of the UV light kills -much like small doses of penicillin vs. heavier -more complete- doses. Then there is the question of developed tolerance...

Well, flow rate affects the time spent in each "round" in the UV light. Try it out, the "S" that is calculated is the survivability of each "round" - i find that for typical flowrates in WC systems, it doesnt vary the survivability much at all.
The only really shady part of my math is that Intensity is measure in mJ/cm^2 - yet we are dealing with the light shining on a VOLUME of water, so i simply used the surface area of that volume. This could be off by a fair margin.

The blue highlighted values are user inputable, where most of the are physical things based on the UV sterilizer you are looking at using and the others are absed on your WC system. Oh and one value is "k", the rate constant, which is different for each pathogen. I pulled one from a source i quoted above -
here

If i examine my spreadsheet, i find that even Airspirit will be satisfied with one fo these, as resevoir size plays a large role also...this is to reference his comment in the previous thread that i dont know how much flow he has Doesnt matter man - you dont have a 300 liter resevoir either. All he needs is one big enough in diameter for his main line.

[Althornin]

Originally posted by h4rm0nix
Also, if we use distilled water -Where are these microorganisms coming from? Airborne?


I think there coming from the deep dark places in our WC setups...the rad.


H

from the rad, from touching the barbs, etc. Did you mouth siphon to start with? etc...
Sterilization isnt really nessesary.

[CoolROD]

Even Airspirit could route some of his water through the UV clarifier...Mabye put it inline with a chipset cooler or something...

[CoolROD]

In Althornin's spreadsheet:

for "% Kill-off Per Day" we have the formula:
=(1-A2^(K5*60*24/I9))*100

If 24 is the number of hours in a day -->and I change it to a 5
--> =(1-A2^(K5*60*5/I9))*100

I still get a result of 99.5763325 effective sterilization in 5 hours.

Al. -Is this correct?

Now I have no idea how often to run this thing. I would definately run it for the first 48 hours, though. And then, what, weekly for a few hours?

I don't want to have to run it unnecessarily...a few extra BTUs, bulb life, etc.