UVB output trough metal mesh

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UVB output trough metal mesh

Postby Sharp852 » Sat Apr 04, 2020 2:04 am

Hello,

I need to calculate amount of UVB which will be blocked by metal mesh, can I safely calculate it and adjust distance by that?
Should I buy solarmeter just to be sure?
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Re: UVB output trough metal mesh

Postby Claudiusx » Sat Apr 04, 2020 5:42 am

Hi Ben,

The easiest way to know would be to have a solarmeter, but with some math and measurements you can find out how much your mesh blocks realitvely accurately. You can find out exactly, but the math is a bit trickier, so this method gives you a close estimate.

You just need to know the gauge of the wire/mesh, or you need to be able to measure the width of the wire/mesh strand with an accurate caliper. From there, you can just count the number of meshes in a sq inch, add up the space taken up by the number of meshes, and use that number to subtract from the area of a square inch to figure how much is being blocked.

The reason this isn't as accurate a method as another more complicated method, is because this method doesn't account for the overlap of wire/mesh crossing over eachother in it's grid like pattern. Still, it would be close enough for this case. Any discrepancy would lead to a difference in percentage of less than half an inch when it comes to figuring your distance.

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Re: UVB output trough metal mesh

Postby Sharp852 » Sat Apr 04, 2020 5:46 am

Claudiusx wrote:Hi Ben,

The easiest way to know would be to have a solarmeter, but with some math and measurements you can find out how much your mesh blocks realitvely accurately. You can find out exactly, but the math is a bit trickier, so this method gives you a close estimate.

You just need to know the gauge of the wire/mesh, or you need to be able to measure the width of the wire/mesh strand with an accurate caliper. From there, you can just count the number of meshes in a sq inch, add up the space taken up by the number of meshes, and use that number to subtract from the area of a square inch to figure how much is being blocked.

The reason this isn't as accurate a method as another more complicated method, is because this method doesn't account for the overlap of wire/mesh crossing over eachother in it's grid like pattern. Still, it would be close enough for this case. Any discrepancy would lead to a difference in percentage of less than half an inch when it comes to figuring your distance.

-Brandon


Hello,
Thanks for a reply. My case is mesh with circles, more like solid metal plate with circles inside it.
Could you in case point me in right direction with this type of "mesh"?
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Re: UVB output trough metal mesh

Postby Claudiusx » Sat Apr 04, 2020 5:53 am

Well, that is more tricky.

However, it most likely isn't blocking very much.

Here is a link to some tests done on metal mesh lids, and flyscreen mesh.
http://www.uvguide.co.uk/fluorescenttubemeshtests.htm

Even with flyscreen being super fine mesh, it still only blocks around 30% of the UV. That's why we typically state that if you place your UV source ontop of your screen, simply account for a 20-30% loss (AKA the bulb needs to be 20-30% closer to achieve the same UVI level at the basking site)

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Re: UVB output trough metal mesh

Postby Claudiusx » Sat Apr 04, 2020 5:55 am

Well, your lid might not be more tricky actually. If you can accurately measure the diameter of the circle cutouts, you can get the area of the circles. Then you do the same thing, take the surface area of 1 square inch, and then subtract from that, the area taken up by the number of circles and half circles in the square inch.

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Re: UVB output trough metal mesh

Postby Sharp852 » Sat Apr 04, 2020 6:05 am

Claudiusx wrote:Well, your lid might not be more tricky actually. If you can accurately measure the diameter of the circle cutouts, you can get the area of the circles. Then you do the same thing, take the surface area of 1 square inch, and then subtract from that, the area taken up by the number of circles and half circles in the square inch.

-Brandon


Thanks for fast reply,
Actually a found one site where you can it seems like, calculate exact percentage.
So it seems it will allow only roughly 30%, does that mean from normal UV index roughly only a third will be really usable?
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Re: UVB output trough metal mesh

Postby Claudiusx » Sat Apr 04, 2020 6:18 am

Ben, that's the beauty of the internet huh? A calculator for everything lol.

Since you're working with such small measurments, you really need to make certain that your measurements are acurate.
For instance, if you're off 1mm on your hole size (D), the difference goes from:

32% open at 3mm
to
58.2% open at 4mm.

Or, lets say you're off 1mm on your pitch. If you are, that's also still 50% open. If you're off on pitch and hole size by a mm, your open area could be 90%!

So it would be best really to have calipers that measure smaller than a mm, that way you could find out if your pitch is 5, or if its 4.5.
You're working with such small numbers here, the difference half a MM makes is huge.

Could you post a picture of your lid?

Would it be feasible for you to cut the area directly under where the UVB would be placed? That would totally negate all this and still allow you to have a working lid to keep things out or in lol.

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Re: UVB output trough metal mesh

Postby Sharp852 » Sat Apr 04, 2020 6:44 am

Claudiusx wrote:Ben, that's the beauty of the internet huh? A calculator for everything lol.

Since you're working with such small measurments, you really need to make certain that your measurements are acurate.
For instance, if you're off 1mm on your hole size (D), the difference goes from:

32% open at 3mm
to
58.2% open at 4mm.

Or, lets say you're off 1mm on your pitch. If you are, that's also still 50% open. If you're off on pitch and hole size by a mm, your open area could be 90%!

So it would be best really to have calipers that measure smaller than a mm, that way you could find out if your pitch is 5, or if its 4.5.
You're working with such small numbers here, the difference half a MM makes is huge.

Could you post a picture of your lid?

Would it be feasible for you to cut the area directly under where the UVB would be placed? That would totally negate all this and still allow you to have a working lid to keep things out or in lol.

-Brandon


Well, thing is that's me planning next plywood enclosures, in which I want T5, enclosures will be 40cm high, and want buy right mesh to not mess anything up, so for now I'm double checking correct mesh/T5/distance combination.
But fortunatelyfound one place where they make exclusively metal meshes like this and also tell you exact open space on each one - max they have is 51%, which could be good for T5 right?
Current enclosures have T8 under the mesh so I don't care about there at least until controller stops working - till then I will just buy new tubes (not to say I didn't thought about replacing 1 month old T8 with T5, but my girlfriend would hate me because of expenses lol)
But let's say T5 I'm looking at have 13UVI on 15cm, then under that 51% mesh it would effectively drop that to roughly 6,5UVI correct?
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Re: UVB output trough metal mesh

Postby Claudiusx » Sat Apr 04, 2020 6:56 am

If you're building the tanks yourself, why not just build them a bit taller so you can mount the UV inside the tank and not worry about the mesh?

If you're going to custom build a screen though, I'm sure you can ask for a bigger % open? Or a slot cut open for the UV to be unobstructed?

But yes you are right, if it cuts it 50%, it needs to be twice as close.

However, I've got to wonder how that might produce shadowing and patterns of light that might not be best.

Truthfully, I'd look into any other option besides settling on placing the UV over something the blocks 50% of it. If you can't get something that is 30% or less blockage, I would find another alternative.

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Re: UVB output trough metal mesh

Postby Sharp852 » Sat Apr 04, 2020 10:36 pm

Claudiusx wrote:If you're building the tanks yourself, why not just build them a bit taller so you can mount the UV inside the tank and not worry about the mesh?

If you're going to custom build a screen though, I'm sure you can ask for a bigger % open? Or a slot cut open for the UV to be unobstructed?

But yes you are right, if it cuts it 50%, it needs to be twice as close.

However, I've got to wonder how that might produce shadowing and patterns of light that might not be best.

Truthfully, I'd look into any other option besides settling on placing the UV over something the blocks 50% of it. If you can't get something that is 30% or less blockage, I would find another alternative.

-Brandon


I through about building it taller already, but for size limitations I want to consider all option, if mesh wouldn't be a good option I would definitely just build it taller and move to other room.
Okay so anything higher than 30% blockade isn't optimal? In terms of UV consistency and light shadows?
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Re: UVB output trough metal mesh

Postby Claudiusx » Sun Apr 05, 2020 7:00 am

Correct, I wouldn't settle for anything higher than 30% blockage.

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Re: UVB output trough metal mesh

Postby Sharp852 » Sun Apr 05, 2020 8:49 am

Claudiusx wrote:Correct, I wouldn't settle for anything higher than 30% blockage.

-Brandon


Great, thanks for answer.
I most likely decided to make a hole in plywood for T5, most likely 6% UVB, could that be? Looking at UVGuide tests, at 20cm its ideal Arcadia T5 6% with reflector.
One thing - are you familiar with Arcadia UVB kits? I'm looking at ProT5, but their UVI readings seem too high, they claim it's because of revolutionary reflector, because its "better than their standalone reflector", is that possible or it's just manufacturers throwing better numbers at us? Because for instance they advertise T8 12% at 30cm but we all know it's best at 15-20cm for ideal UVI.
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Re: UVB output trough metal mesh

Postby CooperDragon » Wed Apr 08, 2020 4:53 am

From what I've seen, Arcadia bulbs have a (slightly) higher output than others even in the same fixtures. 15-20cm should be about right for the 6% with a reflector. As always though, do be sure to provide a nice gradient so that while the highest UVB levels occur over the main basking area, there are shade areas and areas with lower UVB to choose from. They don't always want to be under intense UVB.
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