Cutting Lexan glass and Lexan Reinforced Gypsum

During some training we were discussing how best to cut Lexan glass and how best to breach Reinforced Gypsum.  We don't run into these materials much in my area.  Perhaps, some of the firefighters in Tornado Alley and the Hurricane areas can lend some of there knowlege and experience...

What saws work best?

What blades work best? (I found one post mentioning a Rotary Saw with a "Chunk Carbide" blade)

What training methods are best?

If you are cutting Lexan glass with a rotary blade are enough fumes produced to warrent masking up?

Thanks for any tips or help

Views: 3490

▶ Reply to This

Replies to This Discussion

Permalink Reply by Tyler Lyons on June 6, 2011 at 10:28am
That is on the cockpit window.... a little thicker than your standard Lexan window.... but I guess they used this out of a 79 Javelin. I should have checked with you.
Permalink Reply by Jason Brooks on June 6, 2011 at 1:14pm
A sawzall will go right through them. The CO2 extinguisher does little or nothing for the most part. A chainsaw will work also.
Permalink Reply by Jack/dt on June 6, 2011 at 1:15pm
The first is from San Bernardino County FD's test of reinforced wallboard.
Attachments:
Permalink Reply by Jack/dt on June 6, 2011 at 1:18pm
More info on these type of materials.
Attachments:
Permalink Reply by Tyler Lyons on June 6, 2011 at 2:36pm
Good info... thanks for posting that.
Permalink Reply by Ben Waller on June 6, 2011 at 9:07pm
Tyler Lyons,

Did you ever consider that there is more than one type of Lexan? Did you ever consider that the chemical and structural makeup of the Lexan in the cockpit window might not be the same as the chemical and structural makeup of the modern structural Lexan?

In other words, if you haven't tried the technique you advocate on the EXACT material we're talking about here, you really can't prove that what you advocate will work on those materials.

If you were from Missouri, you'd understand.

Oh, and Tyler, I used to teach fire science at the base where Air Force cockpit windows and canopies are tested. I have a pretty good idea what it takes to make a pinhole in one, let alone what it takes to get an adequate ventilation opening.

You also might want to check out Jason Brooks' reply below.
Permalink Reply by Ben Waller on June 6, 2011 at 9:30pm
How do you make the starter hole for the sawzall? Sawzalls don't exactly make good plunge cuts.
Permalink Reply by lutan1 on June 7, 2011 at 6:04am
Chainsaw is a scary option if we're talking at an MVA. But if the life is on the line.....
Permalink Reply by Tyler Lyons on June 7, 2011 at 8:31am
Ben Waller,

I believe that Ryan posted up about how to cut Lexan glass and about reinforced gypsum. He also posted about the circ saw and what he heard about the blades. So as I explained, I haven't worked with reinforced gypsum, but I have used circ saws with the chunk blade, and you decided that since you don't teach that method that I have no idea what I am doing. You decided that your way is the only way and if you don't teach it, well then it must not be right. I don't care that you taught at the Air Force cockpit window and canopy testing facility. If you did, then you should know that CO2 does work on those. For that matter if you did work with so many cockpit windows during your teaching of fire science, you would know that a circ saw does work. We used those in the Air Force also. I have no problem with debate, but to catch shit from you because "I havn't tried the technique on your EXACT material"... get a life. I agree that there is a lot of different types of Lexan and uses, I am sure that CO2 doesn't work on some types, but some types it does. Get over yourself Ben.
Permalink Reply by Jack/dt on June 7, 2011 at 9:45am
This link - http://www.ppg.com/coatings/aerospace/transparencies1/dc-10finalv7.pdf gives a good idea of how (some) aircraft windows are manufactured.

In the picture posted earlier showing a diagram of an aircraft, the "clearview" window is a SIDE window on an aircraft (that can open). In the links that I found, the clearview window is designated an emergency access point, (chill with CO2 and hit with pickax.) I could be wrong but to me the clearview is specifically designed to be strong enough not to fail in flight but able to be used, in an appropriate manner as an emergency access point. To my totally inexperienced eye, an aircraft windshield would not respond to the methods used for a clearview window, for reasons too obvious to mention.

I only found one mention for cutting a canopy, it referred to an F-22 raptor canopy that was frozen shut. http://www.flightglobal.com/articles/2006/04/25/204883/pictures-pil... After all maintenance options failed the fire department cut the canopy with a chainsaw.

Not sure how lexan would be used in residential applications, I'm guessing that the glass is removed and lexan (plexi) glazed in place of glass. Whether the lexan is 'glazed' with putty and points, glued in (it won't last long anyway), caulked or held in place by an applied molding, if the sheet itself doesn't give with one or two blows from a flathead then a couple of good blows on the wooden (or aluminum) frame will blow apart. I really don't see a need for either a circular or chain saw.

The lexan in reinforced gypsum varies in thickness based on applications. The thinnest, which can be scored with a utility knife and snapped like ordinary drywall, offers a mar resistant surface, The thicker options are more of a security option and present the greatest difficulty to breech. As pointed out in the SBCFD study reinforced gypsum is typically applied to both sides of a steel stud wall so breech of the wall in one room means that the wall on the other side of the studs will require the same effort.
Permalink Reply by Ben Waller on June 7, 2011 at 10:11pm
Nice photo line drawing. I've never seen a house that looks like an aircraft cockpit, though.

When someone installs DC-9 windows in a house, we can be pretty sure that the CO2 trick will work on them.
Permalink Reply by Ben Waller on June 7, 2011 at 10:18pm
Tyler Lyons,

When you tell me that you've tested your techniques on the Lexan found in hurricane-resistant windows in a structure, get back to me.

We both know that the CO2 technique works on some kinds of aircraft Lexan, and we both know it works on '79 AMC Javelin rear Lexan windows.

However, you're just guessing whether or not it will work on the structural window Lexan, because you've never tested that technique. That frankly won't withstand scientific scrutiny.

You're just assuming that it's similar enough that the technique will work, but since you haven't tested your theory in real life, you don't actually have any evidence whether it works or not. Notice that I didn't say that it won't work - just that you haven't done any testing to prove your theory works.

You made the claim - the onus of proof is on you.

I call B.S. on giving you any fecal material, too. Since when is asking questions or pointing out that you used assumptions instead of proving your case a cause for complaint?

As for the "get over yourself" comment, I've found that to be a convenient meaningless comment when someone wants to complain but can't find factual grounds to do so. But, just so we're clear on exactly what you're telling me to do, can you please define what "get over yourself" means and how someone can possibly do it?

▶ Reply to Discussion

RSS

FireRescue Magazine

Find Members Fast


Or Name, Dept, Keyword
• Invite Your Friends
• Not a Member? Join Now

© 2024   Created by Firefighter Nation WebChief.   Powered by

Badges  |  Contact Firefighter Nation  |  Terms of Service