Thread: Newbie Question
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Old October 20th, 2010, 03:36   #8
L473ncy's Avatar
Join Date: Oct 2004
Location: 11-30-24-1W5
Originally Posted by Coresair View Post
Like I said, they are shop glasses Z.87 ANSI rated for impact and they leave almost no space between them and my skin. They look kinda good too.

Anyways, I don't want to down your statment L473ncy, but this is just my 2 cents.
If I had the choice I would use sealed ballistics but the field owner sets the rules and you could risk getting kicked out or banned if the field finds you repeatedly breaking the rules. It's all about insurance really, if the insurance states something you'd better damn well follow it or you won't see any insurance money if they find you were doing even one thing wrong.

I did some back of the envelope calculations a few months ago and my conclusion was that although ANSI Z87.1-2003 is good enough for airsoft, being able to take a steel ball flying at it at however many joules it was it *may* not be good enough for paintball.

Here is my back of the envelope calculations verbatim:

So it's established that for paintball it's roughly 11J for ASTM.

So lets do a test:

From my understanding the ANSI test is done "shooting" 1/4" steel balls at the lenses at various velocities (I assume that's diameter here, so I get approx .1341 cm^3 for volume).

Taking the velocity and weight of a steel ball (assume 100% pure steel) the density is about 7.8 g/cm3 (about 1.05g for a 1/4" steel ball).

So doing the math for the joule conversion of that steel ball being shot at 250 ft/s it comes out to roughly 3.03J, definitely less than 11J.

Even if it was a higher standard (lets say 12J for the ANSI) it isn't stipulated in the fields insurance and as such any insurance claims from the field will be denied.

Also note that a paintball disperses it's energy upon impact by the nature of it "exploding" and splattering paint however an airsoft BB is a "hard" object and does not "destroy" or disfigure itself that much upon impact. Further investigation is probably warranted to see how much "real" (non "wasted") energy is transferred to the goggles from the paintball but I assume that it will probably still be higher than 3J that the ANSI standard is set to. You would have to waste approx. 75% of the energy of the paintball in the explosion/energy wasting stage to be better than the ANSI rating.

Note this is just my ramblings so don't take it as gospel or anything but still consider that ASTM is higher rated than ANSI. ALSO, take note that there are military goggles out there that can stop .50 cal rounds but it doesn't have the ASTM rating so if you're wearing them on the field and a medical emergency/incident happens then the field can have it's insurance claim denied. It's all about following the field owners rules in the end so basically wear the right eye protection and don't get the field owners in trouble or you'll find that access to venues will be VERY limited,
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