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Old 03-23-2006, 04:43 PM
Dennis Brady's Avatar
Dennis Brady Dennis Brady is offline
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Flashback Arrestors

How important are these?
Essential?
A wise safety precaution?
Not really important?

Does it make a difference if it's a small, medium or large torch?
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Old 03-23-2006, 05:07 PM
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Passing Glass Passing Glass is offline
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Re: Flashback Arrestors

Flashback arrestors are a vital safety measure for any and all torches - glass torches, cutting torches, welding torches, any size, anything that has pressurized gas being delivered through a hose or tube through which igniting gas could travel back to the gas source (tank).

They act like a checkvalve and stop the "river" of igniting gas from traveling through the hose into your tank. IMHO, if you are using a set-up which has pressurized gas in hoses, you're nuts if you're torching without one. They are essential for a safe set-up. You don't have to have them, but if something goes wrong, the consequences are just too great to not spend the $30 on them. Be safe, they could save your life AND your house. Plus, if you ever get inspected by the fire marshal, he'll require them.

There are many kinds of flashback arrestors for different applications, but I'm using one that's about 3 or 4 inches long and rather heavy, it's very common. It goes directly on the regulator fitting between the torch hose and the regulator. I'm only using one because I have an oxycon for my oxygen source so I only need an arrestor for the propane. While the oxygen could still flash back, it is under very low pressure from an oxycon so there is no explosion potential. The only thing that would happen is I would ruin my oxycon and possibly start a small fire in the oxycon. If I were using tanked oxygen, however, it could explode and I would need an arrestor for that too.

Arrestors are gas specific, be sure you are using one appropriate for the gas you are using. The ignition point, the flash point, which is the leading edge of a column of igniting gas, gains speed as it travels through the tube or hose. Unchecked, it achieves speeds faster than the speed of sound. You will almost certainly not have time to react to stop a flashback if one occurs. Flashbacks occur more often than you think for a wide variety of reasons. You need arrestors.

Good luck!
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Old 03-23-2006, 07:12 PM
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Re: Flashback Arrestors

What Dan Said.on Any Torch.

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Old 03-23-2006, 08:08 PM
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McDuff McDuff is offline
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Re: Flashback Arrestors

Ditto that! they are like money in the bank.
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Old 03-23-2006, 08:52 PM
aks141 aks141 is offline
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Re: Flashback Arrestors

Quote:
Originally Posted by Dennis Brady
How important are these?
Essential?
A wise safety precaution?
Not really important?

Does it make a difference if it's a small, medium or large torch?

Excellent reply post Dan, I see you becoming the new safety minded guy around here.

I will add that they are not needed for a hothead attatched directly to a one pound MAPP gas cylinder or for some one hooked up to natural gas, there, a check valve is in order.

Dennis, are you really asking? You are in the glass business. This topic has been covered in many threads, I guess I don't see the point in starting another thread.
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Old 03-23-2006, 09:26 PM
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Dennis Brady Dennis Brady is offline
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Re: Flashback Arrestors

Quote:
Originally Posted by aks141
Excellent reply post Dan, I see you becoming the new safety minded guy around here.

I will add that they are not needed for a hothead attatched directly to a one pound MAPP gas cylinder or for some one hooked up to natural gas, there, a check valve is in order.

Dennis, are you really asking? You are in the glass business. This topic has been covered in many threads, I guess I don't see the point in starting another thread.

Yup. I'm really asking. Really curious to see the responses. I've heard contradictory comments (including from suppliers).

We sell everything to do with stained glass, just about everything for kilnforming, and just getting involved in handling torchworking supplies. Of all the 3, torchworking seems to be the one with the least unanimous agreement on various subjects. The question I have to answer for myself, is how strenuously should I push newcombers to buy arrestors when they seem convinced they don't need them - and several other sources have told them they aren't necessary. One major supplier informed me they recommend them only for acetylene. My customers rely on me to supply honest information. I want them to work safely, but also don't want to be advocating buying equipment they might not really need.

I'm wondering how many torchworkers work without arrestors?
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Old 03-24-2006, 02:27 AM
aks141 aks141 is offline
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Re: Flashback Arrestors

Ok Dennis, I assumed you already knew. Sorry. From every thing I've read, it seems like a no brainer to me, I want something between the flame and the pressurized gas. No way would I work without them any more than I would not wear protective glasses or have ventilation.

Have you visited artglassanswers.com? http://www.artglassanswers.com/forum/index.php
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Old 03-24-2006, 08:17 AM
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Re: Flashback Arrestors

I have a question about the flash back arrestors with quick connects!

If I did have a fire inside, and I ran outside to stop my propane from fueling more of a fire, could I just snap click off at the quick connect? Or would that cause the gas to leak out all over and cause the fire to maybe jump from the excess gas?

I guess what I am asking is if you disconnect at the quick connect attached to flashback arrester, would the propane stop and would it be safe? Or would propane continue to leak out? Should I be turning off the knob instead? This would take a few seconds and those seconds might be needed inside to put out anything that might have caught on fire. I have always wondered what to do if I did start a small fire. I always thought the first thing to do was disconnect the propane.
Then deal with the problem.

Sometimes large rods are very shocky and the glass can fly all over. What if it did start a small fire in my torch room? What order should you deal with it? I certainly would not want more propane being fueled into the room while I was dealing with a problem.

I do have 3 extinguishers in my studio, in different areas. It is overkill but....... for the record I wanted to get all my questions answered.
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Old 03-24-2006, 11:12 AM
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Re: Flashback Arrestors

Quote:
Originally Posted by Dennis Brady
How important are these?
Essential?
A wise safety precaution?
Not really important?

Does it make a difference if it's a small, medium or large torch?

They are important... sometimes.
They are essential... sometimes.
They are a wise safety precaution... sometimes.
They are really important... somtimes.
It does not make a difference if its a small, medium, or large torch.

The "sometimes" is when it is a pre-mix torch, not a surface mix torch.
In a pre-mix the gases combine internally before combustion and can backflow in either direction into the opposing gas line, depending on which line has least flow rate - which can especially occur if all or part of the surface orifice is blocked. That is the sometimes. If the torch is a surface mix, the opposing gas cannot feed "backwards", through either line - they are feed by completely separate tube(s) directly into the atmosphere.

Yes there is a lot of conflicting information in lampwork. Partially because the technical reasons for something have been simplified into general rules, since many people don't want to know the details - they just want simple rules - and then they parrot these general rules as absolutes, without the prerequisite understanding of the technical reasons. Many don't even know if thier torch is pre-mix or surface mix. You will see this "general rule" application also in annealing. Kiln manufacturers can make and sell a fully automatic bead annealing kiln for under $99 - but won't, soley because of the mountain of urban myths that have built up about annealing. No one wants to waste thier time, arguing against the myths.

I am an ardent promoter of the POOP safety procedure. This simple rule, Start-Up: Propane On, Oxy On; then Shut-Down: Oxy Off, Propane Off, in that sequence only, is one of the general rules that all lampworkers should follow, even when it is not necessary - because it is a procedural rule. In an emergency people cannot/do not think - they only react, and it is the imprinted POOP procedural reaction that can save them. This rule alone is the most important safety procedure rule in lampworking, and should be emphasized in every studio, and never violated.

As you are certainly aware, it is a losing argument to defend why NOT to do something that a lot of people say is very important, even when they don't know the technical reasons or physics/chemistry involved. So, what to do? Tell'em you have arrestors and they should research it themselves and decide if they should buy/use them. And, like chicken soup... they can't hurt.

Last edited by Padre : 03-24-2006 at 12:10 PM.
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Old 03-24-2006, 11:15 AM
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Passing Glass Passing Glass is offline
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Re: Flashback Arrestors

Quote:
Of all the 3, torchworking seems to be the one with the least unanimous agreement on various subjects. The question I have to answer for myself, is how strenuously should I push newcombers to buy arrestors when they seem convinced they don't need them - and several other sources have told them they aren't necessary. One major supplier informed me they recommend them only for acetylene.


Wow! That really surprises me. I think arrestors are required for any pressurized flammable gas being delivered through a hose (not a hothead connected directly to a cylinder or "hard-plumbed" natural gas). I would recommend them to all of your customers. Of course, you wouldn't need them for a non-flammable gas, but a non flammable gas wouldn't flashback, either. Acetylene, propane, propylene, chemtaine, oxygen, etc... will all explode if a flame enters their storage tank, end of story.

If your customers are not convinced, demonstrate a flashback for them, or videotape it and show it to them. Fill a small balloon with propane and put a small diameter plastic tube in the mouth of the balloon so that the gas in the balloon is forced out through the mouth of the tube and cannot escape from the balloon otherwise. Strike a flame near the mouth of the tube. You will produce a flashback which will travel back into the balloon and *poof*. Just like your tank and your torch hose. Not too dangerous since the gas volume is low and there is no (or little) air in the balloon with the propane. Do NOT mix oxygen in the balloon or allow too much air in the balloon with the propane. That makes a really scary *KABOOM* instead of a little *poof*. LoL

I think the supplier you mentioned said they recommend arrestors only for acetylene because acetylene is much more volatile and flashbacks happen more often with acetylene. Acetylene can become unstable and ignite/explode, for instance, if it is pressurized over 15 PSI in the hose. That's why fuel gas regulators have a red-line at the 15 PSI mark. So they are recommending the safety equipment for the more dangerous gas. But bar-b-que bottles of propane explode too. Every year we hear of someone else who was trying to cook on a modified grill or something and blew themselves up.

For dasi11, IMHO, to handle a small studio fire, the steps I think you should take are 1) Turn off the fuel valve on the torch. 2) Extinguish the fire if it is small enough. You don't want it to burn through your hoses while you're running outside. Then 3) go outside and turn the tank valve off. If the fire is too large to extinguish then just leave it alone and go directly outside and turn the tank valve off, then call 911. I would not worry about disconnecting the hoses at the quickconnects at all. Quickconnects are a convenience device, not a safety device. Leave the quickconnects alone and let the flashback arrestor do it's job if necessary - they work. Your job is to get that main tank valve shut and then most of the danger is gone - unless your oxygen tank is getting cooked by a large fire back inside .

Everyone else, thanks for the welcome! I'm enjoying it around here and learning alot - great site! I hope I can contribute in a meaningful way!
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Old 03-24-2006, 11:36 AM
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Re: Flashback Arrestors

"If I did have a fire inside, and I ran outside to stop my propane from fueling more of a fire"

You need a ball type shutoff valve...where the gas enters the building...on the inside.

Safety,Safety

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Old 03-24-2006, 11:44 AM
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Re: Flashback Arrestors

Padre, you snuck a post in on me! That's a good point about pre-mix vs. surface mix torches. I always forget that the pre-mix variety it out there, thanks.

One question for you - you mentioned the POPO method for startup and shutdown. Everything I've ever read has said to use the POOP method. Do you know the details or reasons behind one or the other, or why one is better than the other? More confusion for the lampwork world.
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~ A man with a watch knows what time it is. A man with two watches is never sure. ~
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Old 03-24-2006, 12:25 PM
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Re: Flashback Arrestors

Quote:
Originally Posted by Passing Glass
Padre, you snuck a post in on me! That's a good point about pre-mix vs. surface mix torches. I always forget that the pre-mix variety it out there, thanks.

One question for you - you mentioned the POPO method for startup and shutdown. Everything I've ever read has said to use the POOP method. Do you know the details or reasons behind one or the other, or why one is better than the other? More confusion for the lampwork world.

You are correct.
I edited the post.
POOP is correct.
I was having a deep discussion last night with someone who proposed POPO and I somehow got fixated (reversed) when I posted here.

The discussion last night centered on first removing the fuel (propane) in an emergency, then removing the what sustained the fire - the oxy - thus making it POPO. Their rationale was that removing the propane first, removed what fueled the fire (which could easily be done with a torch fire versus an oil well, forest, or house fire where you can't remove the "fuel"). I was still mulling that this morning when I posted and it somehow snuck in. And I'm still thinking about it. Good catch.
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Old 03-24-2006, 12:44 PM
PamDugger PamDugger is offline
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Re: Flashback Arrestors

Yay, someone has it right. Thanks, Padre, for the info on flashback arrestors so lucidly explained. People always look at me like I am crazy when I say I believe arrestors are not necessary for surface mix torches. I've actually stopped saying it.
Pam
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Old 03-25-2006, 11:37 AM
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Re: Flashback Arrestors

I think you need to look past what kind of torch you have when deciding if you need flash backs.Anything can happen from the torch to the tank and has.Any fule line like that SHOULD have them.Is it worth 50 bucks to loose everything ????????????????????????????????.

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