Screen Size Confusion

[LSchenck]

Does anyone have the definitive word on which screen sizes are needed for basic pyro? Making a couple of sets of screens is one of my first projects and I want to get it right. I've read a ton of stuff on this and the only thing that is consistent from one place to another is that a 100 mesh screen means 100 wires per inch. HOWEVER that says little to nothing about the opening between the wires.

 

For example Pygoguide has a discussion on mesh size that says a 100 mesh screen has an opening of 89 microns. Two different stainless screens from "TWP" (a company that specializes in wire mesh products) has a spec sheet showing a 100 mesh screen with 0.0011-inch wire with a 203 micron opening and another with 0.0045-inch wire with a 140 micron opening. Skylighter sells screens but doesn't give any information except for the mesh count.

 

A range of 89 microns to 203 microns is a bit too much! The same problem applies for all mesh sizes I checked.

 

So. Wouldn't it be better to specify particle size instead of mesh and then slect a screen that provides that performance? And where can I find that information?

 

On another slant.... Is there a place that sells smaller amounts at reasonable prices? TWP prices are in the $7/square foot range but you have to buy a minimum of 10 to 15 square feet of each size. Still that is less than a third of the unit price of the Skylighter screens.

[stug161]

 

I ordered mine from McMaster Carr. They have every kind and size you could want. Different materials too, but I think Stainless 504 is what I used, as I saw it elsewhere used in pyro. I bought 20,40.60,80,100 1 square foot each. With shipping it was around $35 Their site is awesome, and they have very specific listings as to wire thickness and percentage of openings and such. I went small and cheap for my screens. I bought 4" PVC couplers and cut out the screens to fit. If you are careful you can get 5 from each sheet. Then I hot glued them together. They make a small yet cheap and easy screen.

 

Good luck! Robert

[LSchenck]

McMaster Carr has a perfect example of why I am unsure what to buy. Check the entire page here http://www.mcmaster.com/#stainless-steel-screens/=3b00y9 . Simply stating mesh count is virtually meaningless. Perhaps it is the chemist in me that doesn't feel too comfortable with qualatative things. Especially when the details are provided.

 

In the end though I guess I'll just buy a bunch and hope it works out. I especially like your idea to go small with the PVC couplers to get started. That way the investment won't be too great if it turns out to be wrong there is no great loss.

Edited August 23, 2009 by LSchenck

[TYRONEEZEKIEL]

Perhaps it is the chemist in me that doesn't feel too comfortable with qualatative things.

 

 

It could just be me, but I would rather have qualitative over quantitative.

[KruseMissile]

This should help http://www.fluideng.com/FE/meshmicron.html It's not that hard to find the mesh you need at the site, its actually very simple.

[LSchenck]

This should help http://www.fluideng.com/FE/meshmicron.html It's not that hard to find the mesh you need at the site, its actually very simple.

 

 

Thanks. That answers the mail.

[Arthur]

Pyroguide has all sorts of info collated inc mesh sizes and BP F's to mesh size charts

http://www.pyroguide.com/index.php?title=Main_Page

 

Cooperman supplies meshes in 12" squares

http://nexusgamers.co.uk/catalog/index.php...83d397809dcf08f

 

Inoxia supplies meshes in 4, 6 ad 12 inch squares.

http://www.inoxia.co.uk/rw/category/9.aspx

 

Read widely! the US standard meshes are a bit different from the UK/EU sizes like the wire gauges are different

 

You could want two sets of meshes! one in the 100mesh and coarser for BP sizing, the other set 100 - 600 for ingredient sizing.

 

If you ever use chlorates then you need another complete set of meshes for the chlorate comps too.

[Mumbles]

Luckily enough, quantitative particle size doesn't matter very much. There is so much variation in supply, materials, and processes that even with identical sized chemicals, two people will build 2 different shells.

 

I also got my screens from McMaster. I obtained some 6qt plastic containers from wal-mart, cut the bottoms off, and melted the plastic into the mesh. I was there earlier today to get some more, and noticed that they changed the design. I don't know if I like it. They don't seem as easy to manipulate as the old ones. I also don't know if they'll mate with my other screens. A 6x12" piece of screen is all that is needed to make them. I split the other half with another pyro.

[Swede]

LSchenck, welcome. I was once a chemist too, long ago. We tend to be very numbers oriented, and worry over details like the size of the mesh opening. The reality is, these devices work fine without the need to be hyper-precise about the screen size. The fine meshes (like smaller than 100) see little use by most guys, and maybe 4 screens from 5 to 40 will do 90% of what you want.

 

Don't fret too much, just buy one of those stainless screen assortments, from 5 to 100, and make a set of devices that can be easily hosed down to clean. Plastic bucket screens are the best IMO. I made some with wooden frames, and I had to seal the edge with fillets of epoxy, and give them some heavy coats of polyurethane. Too much work.