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How do I build a flash suppressor?
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mojoman317717 Offline
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Post: #1
How do I build a flash suppressor?
I keep reading threads that mention a home made flash suppressor. To be clear, I'm not talking about a bubbler, though I know they can serve as a flash suppressor. I already have a bubbler and don't want another one. I need to know how to build a dry flash suppressor. I hear things about tubing stuffed with brass wool, or some kind of aquarium media, but I can't find a decent explanation of exactly how to construct one that is truly useful.

Someone please step up and fill in the blanks please.
(This post was last modified: 10-30-2010 09:49 PM by mojoman317717.)
10-30-2010 09:48 PM
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Zipstor Offline
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Post: #2
RE: How do I build a flash suppressor?
The idea behind a fire trap or flashback arrestor is to divide the space in small areas (I think from memory 1/10 of a millimeter) to avoid the combustion to spread. You can find some interesting videos on youtube on that subject.

It depends what flow you need to go through.. You can try to enclose an air stone inside a tube and 2 fittings on each ends or fill the tube with fine stainless steel wool. Make sure you pack the wool hard and make some tests with a ball valve upstream.

The best is the air stone because minerals don't burn as fast as metals.

>> http://brownsgas.com
10-31-2010 03:53 AM
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benny Offline
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Post: #3
RE: How do I build a flash suppressor?
(10-31-2010 03:53 AM)Zipstor Wrote:  The idea behind a fire trap or flashback arrestor is to divide the space in small areas (I think from memory 1/10 of a millimeter) to avoid the combustion to spread. You can find some interesting videos on youtube on that subject.

It depends what flow you need to go through.. You can try to enclose an air stone inside a tube and 2 fittings on each ends or fill the tube with fine stainless steel wool. Make sure you pack the wool hard and make some tests with a ball valve upstream.

The best is the air stone because minerals don't burn as fast as metals.

Sorry Zippy. You don't win a watch this time. Try again.

The idea behind a flashback suppressor is to rapidly remove heat from the flame front as it passes through the flash arrestor, hopefully to a point where there is insufficient temperature to maintain combustion of the gases in your tubing at the incoming side of the flash arrestor.

Bronze wool is preferrable to stainless steel. Try googling for flashback arrestors. There are plenty of examples on the internet.

A ball valve is a total waste of time and money. Way too slow in reacting to the pressure pulse from the flame front to close in time to stop the flame front passing through same.

Your bubbler is probably the best flame arrestor.
(This post was last modified: 10-31-2010 12:07 PM by benny.)
10-31-2010 11:56 AM
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mojoman317717 Offline
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Post: #4
RE: How do I build a flash suppressor?
Ok, I found a couple of simple designs involving 4 inches of tubing stuffed with brass wool. One used plastic tubing, while the other used copper. Seems to me the metal would be a better choice because of it's ability to dissipate heat, but the plastic one seemed to work fine when tested in the video. Anyone have an opinion either way?

Again, this is just a second level of protection after the bubbler.
10-31-2010 01:48 PM
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Zipstor Offline
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Post: #5
RE: How do I build a flash suppressor?
Heat? There is no heat involved on a HHO flash unless your wool catches fire.

So Benny why would you prefer bronze wool over ss? I'm using fine ss wool and i'm pretty happy with it, as long as it does not get wet..

I mentioned a ball valve not as a check valve but like a quarter turn tap in order to test the fire trap. Flow the gas, shut the valve and ignite.

To Benny: "This is a ball valve"
[Image: ball-valve.jpg]

>> http://brownsgas.com
(This post was last modified: 11-02-2010 01:45 AM by Zipstor.)
11-02-2010 01:39 AM
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benny Offline
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Post: #6
RE: How do I build a flash suppressor?
(11-02-2010 01:39 AM)Zipstor Wrote:  Heat? There is no heat involved on a HHO flash unless your wool catches fire.

So Benny why would you prefer bronze wool over ss? I'm using fine ss wool and i'm pretty happy with it, as long as it does not get wet..

I mentioned a ball valve not as a check valve but like a quarter turn tap in order to test the fire trap. Flow the gas, shut the valve and ignite.

To Benny: "This is a ball valve"
[Image: ball-valve.jpg]

OK Zippy. I see you still haven't quite grasped the basic concepts of physics 101.

Physics 101: flame >> heat>>gas>>more flame>>more heat>>ad infinitum. Heat is a byproduct of any burning substance, including HHO gaseous mixture, sometimes a desirable effect, sometimes not as in the case of HHO production,. At least this is the case on this planet. Might be different where you come from.

Physics 101: Heat transfer from burning combustible gas to unburnt combustible gas is required to ignite the unburnt gas, an action which produces your flame front, which passes through your volume of gas.

Physics 101: Bronze wool is preferrable to SS because of the greater heat transfer rate of bronze wool. Thermal conductivity. Helps dissipate the heat better. See above.

I'll give you 4/100 for your ball valve idea. I do know what a ball valve is. BUT . . .

Plumbing 101: Note that not all types of ball valve are suitable for working with gas. Personally I certainly would not want to rely on same as a secondary flame arrestor, or flashback arrestor, in the event that your primary flame arrestor fails.
(This post was last modified: 11-02-2010 08:41 AM by benny.)
11-02-2010 07:19 AM
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mojoman317717 Offline
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Post: #7
RE: How do I build a flash suppressor?
I think we need to nail down exactly what the flash suppressor actually does in order to arrest the flame.

Zipstor: Of course there is heat! As the hydroxy gas burns there is definitely heat. Ignition is nothing more than heat. The heat usually comes in the form of a flame or spark, but ignition could occur with a metal rod heated to glowing red for example.

My understanding is that the flash suppressor dramatically reduces the heat below the point that will continue to ignite the hydroxy.

Fire requires three things: Fuel, Heat(ignition), and Oxygen. Remove any of these three and flame cannot be sustained.

The flash suppressor is not removing either oxygen or fuel, so it must be a function of it's ability to reduce the heat.

I suspect brass is preferred because it is less likely to oxidize and corrode, especially as some of these hydroxy boosters are producing water vapor, and it has a higher melting point than does steel, making it able to absorb more btu's effectively.

Does that make sense?
11-02-2010 07:43 AM
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benny Offline
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Post: #8
RE: How do I build a flash suppressor?
(11-02-2010 07:43 AM)mojoman317717 Wrote:  I think we need to nail down exactly what the flash suppressor actually does in order to arrest the flame.

Zipstor: Of course there is heat! As the hydroxy gas burns there is definitely heat. Ignition is nothing more than heat. The heat usually comes in the form of a flame or spark, but ignition could occur with a metal rod heated to glowing red for example.

My understanding is that the flash suppressor dramatically reduces the heat below the point that will continue to ignite the hydroxy.

Fire requires three things: Fuel, Heat(ignition), and Oxygen. Remove any of these three and flame cannot be sustained.

The flash suppressor is not removing either oxygen or fuel, so it must be a function of it's ability to reduce the heat.

I suspect brass is preferred because it is less likely to oxidize and corrode, especially as some of these hydroxy boosters are producing water vapor, and it has a higher melting point than does steel, making it able to absorb more btu's effectively.

Does that make sense?

Near enough. Don't use brass wool. Bronze wool is what is recommended, by reason of its resistance to corrosion.
Aquarium bubbler stones are fragile in nature and, when used as flashback arrestors, may not survive multiple flashbacks..

More information here :
http://www.handyman-source.com/7429/warn...arrestors.


Zippy. You will no doubt be pleased to note that your status has been uprated from F_zero_zero_L to ID_ten_T. A vast improvement but it is recommended you stick with your studies. There is still room for more improvement.
(This post was last modified: 11-02-2010 12:31 PM by benny.)
11-02-2010 08:38 AM
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Zipstor Offline
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Post: #9
RE: How do I build a flash suppressor?
(11-02-2010 07:19 AM)benny Wrote:  OK Zippy. I see you still haven't quite grasped the basic concepts of physics 101.

Physics 101: flame >> heat>>gas>>more flame>>more heat>>ad infinitum. Heat is a byproduct of any burning substance, including HHO gaseous mixture, sometimes a desirable effect, sometimes not as in the case of HHO production,. At least this is the case on this planet. Might be different where you come from.

Physics 101: Heat transfer from burning combustible gas to unburnt combustible gas is required to ignite the unburnt gas, an action which produces your flame front, which passes through your volume of gas.

Physics 101: Bronze wool is preferrable to SS because of the greater heat transfer rate of bronze wool. Thermal conductivity. Helps dissipate the heat better. See above.

Okay I'll try bronze wool... but my FBA made with ss is 100%... I will post a video of my whole setup very soon.

(11-02-2010 07:19 AM)benny Wrote:  I'll give you 4/100 for your ball valve idea. I do know what a ball valve is. BUT . . .

Plumbing 101: Note that not all types of ball valve are suitable for working with gas. Personally I certainly would not want to rely on same as a secondary flame arrestor, or flashback arrestor, in the event that your primary flame arrestor fails.

The ball valve is not used as a FBA in my example. I only use it to shut off the gas before I would ignite the FBA in a test condition to make sure the fire does not reach my setup. If you are testing a device and it fails you want to have peace of mind when you do that. Or I use a FBA instead that I'm 100% confident with... in his case he does not have any to start with so this is why i suggested that.

(11-02-2010 07:19 AM)benny Wrote:  More information here :
http://www.handyman-source.com/7429/warn...arrestors.

Skinny FBA = little flow

>> http://brownsgas.com
(This post was last modified: 11-03-2010 01:41 AM by Zipstor.)
11-03-2010 01:18 AM
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benny Offline
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Post: #10
RE: How do I build a flash suppressor?
Quote:Skinny FBA = little flow

Partly correct, but resistance to gas flow also means a pressure build up in your HHO generator system. More pressure = greater rate of flow. Increased pressure tends to compensate for resistance to gas flow. May be less gas volume flow but gas is also compressed somewhat at the increased pressure level. When past your obstruction, (FBA = resistance to flow) the previously compressed gas will expand in volume. The rest you can work out for yourself.

Trade off one against the other.
(This post was last modified: 11-03-2010 05:26 AM by benny.)
11-03-2010 05:25 AM
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