Welding Tips and Tricks

Want to add a class D extinguisher to shop just in case. Deal with magnesium cases and parts with would like to have something better then a bucket of sand. Unfortunately class D extinguishers cost a small fortune, but still cheaper then a fire out of control. Anyone have one in there shop curious as to cost of getting them recertified and how often they should be recertified.

Also if anyone has thoughts on what chemical is best suited seems to be a few different types available and any certain brands to avoid.

Yes, A class D extinguisher is going to be an arm and a leg to buy, but they are invaluable in the case of a D fire. I have not looked into D extinguisher maintenance before, but it is all covered in NFPA 10 which is the standard for all extinguishers. I did find an owners manual for a D extinguisher from Amerex and they listed the same maintenance for the D as any other ABC. A monthly user inspection, a yearly external inspection, and a 6 year internal inspection. I didn't see it specifically, but I assume they have the same 12 year hydrostatic test as standard ABC cylinders.

http://amerex-fire.com/wp-content/uploa ... uisher.pdf

As for cost of inspection and testing, I don't know on that. The extinguisher testing facility will have to be set up for Class D powder, so they may charge more for that, I just can't tell you from experience. I would suggest that you call your local extinguisher shop and find out what they charge for the 6 and 12 year for the ABC vs. D.

For brands, I don't think you can get a cheap throw away Class D. The two brands that I have had good luck with, and I am not excluding others I just don't have experience with them, are Amerex and Ansul Sentry. Both are big names in extinguishers and are decent, serviceable units. In my experience I give a slight edge to the Ansul, because they have steel handles and the Amerex has aluminum. I have found that the aluminum tend to get bent easier both on fire trucks and in industrial settings. That being said, I have effectively discharged extinguishers from both companies that have been total trash, abused, out of date, and run over and they still worked. As long as they held pressure, they would still put out a fire.

All that being said, I have used another product that is effective on Class D fires in a water based foam type solution. I have never used it in a portable extinguisher, and I do not know if it is suitable for an extinguisher, but you might want to call and inquire about it. The product is from Hazard Control Technologies and it is called F-500. It is an agent that is very similar to foam as that you mix it with water and apply like water. I have used this at a Fire Department level with very good success. And I know of one large city departments that has a magnesium processing facilities in their city that now uses this exclusively. Again I do not know that this translates down to the extinguisher level, but it would be worth contacting the manufacture and requesting a demonstration.

http://www.hct-world.com/products/chemi ... tor-agent/

Good Luck, and I am sure that someone here will have more specific experience with Class D extinguishers.

Thank you Airrj for the info i appreciate it. Especially from someone using the stuff to fight fires.

That F500 stuff is pretty cool never heard of it. apparently it can be used in an extinguisher. Found a video where they show how to refill and charge an extinguisher with F500, however that video doesn't specify class D so maybe it doesn't have enough knock down in such a small amount for a D fire. I have an enquiry out to them for info on using it in an extinguisher for D fires. That would be great if it is usable. Easy to recharge over the other class D extinguishers. I will post the answer they give me. Before that was considering the graphite based unit. I bet that is messy as heck to clean up though. What sucks is D units start about 400 to 800 for an extinguisher, can get ABC for around 70 to 120. Hopefully I can get a deal with a local supplier to buy a D and a few ABC's at same time maybe can get it a little cheaper if I get a few of them.

If you wouldn't get so rowdy when repairing cases, a fire extinguisher would be a non issue

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GreinTime wrote:If you wouldn't get so rowdy when repairing cases, a fire extinguisher would be a non issue

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Not a matter of being rowdy just paranoia with old age I guess in case something out of the blue happens. Its some of the small mag parts that bother me the most. Figure it's easier to be at that critical temp with those little parts then a center section of a rear end.

Also F500 does work with It in an extinguisher for class D per the company.

If you do get some F-500 you can always do a test run. A little magnesium scrap in the backyard fire pit and a test run with the water can.

dirtmidget33 wrote:...Its some of the small mag parts that bother me the most...

For small parts, you can simply keep a bucket of fine silica sand handy. If a part burns, burying/covering it in sand immediately stops the spread, and the heat of a metal fire will melt the sand into glass, quickly shutting off oxygen. The down-side is sand is a great insulator, so you've got to leave it alone for a while so it doesn't re-ignite when you clean it up.

This is not the perfect solution, but for small parts it's far better than having nothing until you settle on a better answer.

This is something that, as another posts suggests, can be proven outside in the fire-pit with some scrap magnesium to increase your confidence. If you do this test, wear your hood... Burning magnesium is as bright as a welding arc.

Steve S

Otto Nobedder wrote: Burning magnesium is as bright as a welding arc.

Steve S

It's brighter in my opinion and Damn fast. Long time ago someone used my bench grinder on some mag part they thought it was aluminum. I used grinder next as soon I touched that piece of steel to wheel big bright whit flash erupted inside the grinding wheel covers and behind it where mag particles where deposited before. It was bright as hell and quick. Luckily it burnt so fast nothing else caught fire. Plus everything close buy wasn't easy to ignite. I was P)$$ed. I have some sand handy I agree it is a good cheap solution to have on hand and hopefully it would work. The one thing I learned from that experience was you can't see nothing in a mag fire and it's hot as hell, that flash put off a tremendous amount of heat, worried about how close I need to get to dump sand on it and being blinded at same time. I haven't had a mag issue since that time but worry about it now days. Of course I find myself paranoid about a lot of things as time goes on. Off topic here but think it is factors of getting older, (wiser maybe), having kids, and the BIGGEST factor (I think) being hurt bad enough and finding out that you can be in excruciating pain on fentanyl and morphine in a hospital and still feel PAIN BAD.

I found some good fire nerd reading tonight.

http://fire.nist.gov/bfrlpubs/fire98/PDF/f98052.pdf

I didn't read the thing cover to cover, but the magnesium section was an interesting read.

The biggest problem with any type of sand is the level of moisture in the sand. The fine silica sand that Steve mentioned sounds like it could be a good option if it is in a seal dry container. The problem is that when you are putting the media on a burning material you are most likely at arms length and an explosion without proper PPE would be bad. Soda ash is a common media as well for burying Class D fires.

If I was going to protect my shop from Class D fires with dry agent, I would keep a Class D extinguisher on hand to put the first layer of agent on the burning material, and I would also keep one or two 50lb. sealed packages of soda ash to apply extra layers on top of the burning material.

Remember a burning part may be 3D in nature. If the burning part is tall and slender, you will need allot more agent to cover the part than if it is a flat round part on a table or the floor.

Thanks.
R.J.

dirtmidget33 wrote:Want to add a class D extinguisher to shop just in case. Deal with magnesium cases and parts with would like to have something better then a bucket of sand. Unfortunately class D extinguishers cost a small fortune, but still cheaper then a fire out of control. Anyone have one in there shop curious as to cost of getting them recertified and how often they should be recertified.

Also if anyone has thoughts on what chemical is best suited seems to be a few different types available and any certain brands to avoid.

use a 50/50 mix of fine sand and plaster of paris
the name of the game is to smother a magnesium fire as it cannot be doused with water!
fine sand will have the weight and the plaster of paris will smother the flame by displacing the oxygen
and i believe heating the plaster may release some co2 as well

Copper-based Class-D extinguishing powder is AFAIK only really required for Lithium fires as it burns extremely hot and needs the 'heat sink' capacity of the copper to also draw heat away as quick as possible.

Another option for Class-D extinguishers is that they are filled with a powdered salt (pretty common NaCl really..) which settles on the fire, melts and solidifies and then robs the material of it's oxygen supply. Works on metal fires that are not lithium based.

They tend to be a little more affordable than the copper-powder ones. Still not realy cheap, but at least a little less 'ouch'

Bye, Arno.

airrj wrote:I found some good fire nerd reading tonight.

http://fire.nist.gov/bfrlpubs/fire98/PDF/f98052.pdf

I didn't read the thing cover to cover, but the magnesium section was an interesting read.

The biggest problem with any type of sand is the level of moisture in the sand. The fine silica sand that Steve mentioned sounds like it could be a good option if it is in a seal dry container. The problem is that when you are putting the media on a burning material you are most likely at arms length and an explosion without proper PPE would be bad. Soda ash is a common media as well for burying Class D fires.

If I was going to protect my shop from Class D fires with dry agent, I would keep a Class D extinguisher on hand to put the first layer of agent on the burning material, and I would also keep one or two 50lb. sealed packages of soda ash to apply extra layers on top of the burning material.

Remember a burning part may be 3D in nature. If the burning part is tall and slender, you will need allot more agent to cover the part than if it is a flat round part on a table or the floor.

Thanks.
R.J.

I saw something just today that backs this up... Magnesium is so reactive that it can, when burning, break down any hydrates or hydrites in the sand, regardless of how "dry" it may be.

The best suggestion was to just let it burn out, while working to control any fires around it that are started by it.

Steve S

dirtmidget33 wrote: Long time ago someone used my bench grinder on some mag part they thought it was aluminum. I used grinder next as soon I touched that piece of steel to wheel big bright whit flash erupted inside the grinding wheel covers and behind it where mag particles where deposited before. It was bright as hell and quick. Luckily it burnt so fast nothing else caught fire. Plus everything close buy wasn't easy to ignite. I was P)$$ed.

I'd be P)$$ed if someone used aluminium on my bench grinder! That's what linishers are for. But then again maybe I'm just too pedantic..

I wasn't happy about it when i seen the wheel embedded with what looked like aluminium, but I couldn't really chew him out. He didn't have experience and had no clue that aluminum clogged up the wheels. I did explain to him later especially after it lit up but that was after the fact. I was in a hurry at the time and didn't even bother to dress the wheel to try and clean it out at the time next thing WHOOOSSH followed by mother %+%-#-%+#-#-$:"'*-#