thematrixiam

DIY Static mixer

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Hey guys.

I was wondering if anyone has figured out a good way to make a DIY static mixer that works well and is cheap.


How long should they be? Where should they be connected in the system? 
My ribbon connections are 2" BIP.... I have two Ribbon Burners that are 6" x 3" with 1/2 " over lap for grabbing the cast... so the possible burner space would end up being 5" x 2" for each... Total of 10" x 2" with both combined. 
 

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Ah HAH, BIP means Back Iron Pipe?  Those are called "Nipples" at the plumbing supply so we use the industry term. It really saves confusion, the guys up the road from me would just give me THE LOOK if I asked for a couple BIPs.

Seeing as the fuel air mix is flowing through the system there can NOT be a static mixer, static means motionless.

I've already made my suggestion in your other post no need to change or add more here.

Frosty The Lucky.

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BIP does mean Black Iron pipe. Schedule 40 to be precise.

Sorry. I work in gas fitting and sheetmetal, so it's work jargon from my end. I just assumed that you guys would know that.

As per the Nipple term, you can also call anything of short size a nipple. 

If they looked at me funny when I said BIP or SS or 636, I would also look at them funny. Considering it's my trade. 

Saying industry term to me is kinda weird. But okay. 

re: "Seeing as the fuel air mix is flowing through the system there can NOT be a static mixer, static means motionless."
hmmm. this is incorrect. A static mixer mixes without moving because the medium is moving. 


 

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13 minutes ago, thematrixiam said:

A static mixer mixes without moving because the medium is moving.

What part of a forge burner moves? The ONLY thing moving in mine is the fuel air mix.

What I'm wondering here is what kind of burner mixer moves to function? 

Frosty The Lucky.

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This is a static mixer:

mixer.jpg.0270892fd71df5c9d7e7a903598be1bd.jpg

It goes after your primary air and fuel to mix them together before they get to the burner. It does not move. Your air moves. It helps mix the gases. It is also what the industry(sic) uses.

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My forge just has an elbow in the line to make turbulence for mixing.

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90s don't really offer much in the way of turbulence. About the equivalent of 10' of straight pipe.

Check how the static mixer actually blends the material over time. A 90 would not do the equivalent. 
 

 

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I found this on eBay. They seem to be pretty spendy, but I am not sure why. It looks like it would be easy to make one. 

DF7B83FB-C8C6-4404-B565-743C19C3F068.jpeg

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All I could think of when watching that video was "So that design makes Damascus of my gas flow?"

Diffusion in these turbulent conditions is appreciable, unless you need a very compact design it'd be cheaper to add another elbow and a little more pipe length... or just snip a few blades to put in the pipe out of an aluminum can.

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So, anyone?

Re:

On 4/13/2019 at 7:17 AM, thematrixiam said:

I was wondering if anyone has figured out a good way to make a DIY static mixer that works well and is cheap.

90s or even baffles do not mix as good as a static mixer.
I am asking if anyone knows how to make one.

I understand that this technology is new to some of you. But that does not mean that it does not work, nor that it is too hard to make, nor that it is expensive to make.

I like the amount of discussion that my post is getting. But so far the only constructive post was from the Administrator that said: 

 

12 hours ago, Steve Sells said:

thats so cool


I think I might have figured out a solution to make a cheap static mixer. 

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There's a brief discussion relating to your question on this thread - partway through.

https://www.iforgeiron.com/topic/57609-drilled-no-crayon-ribbon-burner/?tab=comments#comment-606020

I think Ted Ewert posted a picture somewhere of a device he created to get good mixture for a blown burner, but I could not find it in my brief search.

 

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23 hours ago, DHarris said:

I found this on eBay. They seem to be pretty spendy, but I am not sure why. It looks like it would be easy to make one. 

This one caught my eye, I wonder if these could be modded so hole is at the centre of each twist, and then we stick it in a NA burner. Probably would cause too much turbulence but would be a fun test.

 

thematrixiam,

as for making these, what about cutting some steel part way through and then twisting? with a blown burner would it matter if these static mixers are super accurate? 

Vincent

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12 minutes ago, Vincent Tai said:

as for making these, what about cutting some steel part way through and then twisting? with a blown burner would it matter if these static mixers are super accurate? 

Vincent

I have some galvanized sheet metal I was going to try to make some with...

Basically. I am thinking getting about a 18" of 2" Ѳ BIP (Black Iron Pipe) [Ѳ  means round]

Then also get two of 2"Ѳ  to 1 3/4Ѳ  reducers. 
Thread on one reducer on the 2"Ѳ  pipe.
Drop in a chained together twist that are alternating.
Close with another reducer.

That's the best I can come up with right now. But I see no reason why it wouldn't work. 

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18 hours ago, HojPoj said:

"So that design makes Damascus of my gas flow?

Do you need a special device to make your DamGasus flow, HojPoj? :wacko: (Lord I LOVE a good straight line! Thank you.)

I'd still give twisted perforated sheet a try before getting into something harder to make. Every perforation will cause local cavitation and the twisted strip will induce swirl. 

Test in clear plastic tubing with a smoke injector and air flow. Measure the distance. You can model it with water and food coloring as well. I did my initial modeling with smoke but went to food coloring and water when I was trying to see what the air and gas jet were doing in NA burners.

I don't think I learned anything significant other than the professionals were right about the tube length to diameter of the throat ratio. It was cool to mess with though.

Frosty The Lucky.

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2 hours ago, Frosty said:

I'd still give twisted perforated sheet a try before getting into something harder to make

I wouldn't be a good sheet metal worker if I couldn't build a twist.

 

2 hours ago, Frosty said:

than the professionals were right about the tube length to diameter of the throat ratio.

Are you building pipes? or sending gas through duct work? Please elaborate on what you are saying.

Myself being a professional in air movement, and gas piping, I find your reference lacking information. Or do you mean engineer?

A centre line radius of a fitting can increase or decrease turbulence.
Pipe 90s can come in various slopes/centre-line radiuses. But, in general, they are fixed and never changing; especially in gas. If you go to a wholesaler you may have more options available, though. But then you have the problem of them maybe not selling to you if you are not a gas fitter.

 

 

3 hours ago, Frosty said:

modeling

I posted a video of the fluid dynamics involved with that static mixer design. 

 

 

3 hours ago, Frosty said:

I'd still give twisted perforated sheet a try before getting into something harder to make.

Confused by this. Perforated would be harder to bend than non perforated.

 

Found a fluid dynamic video of a 90
 

 

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On 4/13/2019 at 8:11 PM, thematrixiam said:

BIP does mean Black Iron pipe. Schedule 40

Actually I've heard BIP referred to in the field as any black steel pipe (including schedule 10 and schedule 80), but that may be a local aberration.  Admittedly the most common usage is for standard weight pipe, which is schedule 40 up to 10" diameter.

I've never needed any kind of flow mixing accessories for my natural gas/forced air burners.  I do know that some folks who feel they do have made up special mitered elbows that make a right angle bend and induce more mixing, or mount their blowers rotated 180 degrees out of line so the fastest part of the flow from the blower impacts the "shorter" side of the elbow (less efficient, but leading to more mixing).

On 4/13/2019 at 8:48 PM, thematrixiam said:

90s don't really offer much in the way of turbulence. About the equivalent of 10' of straight pipe

I'm not exactly sure what you mean by this.  Typically equivalent feet of pipe is a measure of pipe friction, not turbulence.  Note that per the Cameron Hydraulic data the equivalent length of a 2" diameter 90 degree elbow is 5.17' and for a long radius elbow only 2.76'.  It is very different depending on pipe diameter and this is for normal range of turbulent liquid flow, not gaseous.  For gaseous fluids it depends a lot whether you are operating in the turbulent range or laminar range (as determined by the fluid's Reynolds number, a function of the inherent kinematic velocity of the fluid at it's static pressure and the velocity the fluid is flowing at).  In my experience the flow in the mixing tube is most likely turbulent, throughout it's range of operation, which has an effect on the duct friction loss (using duct here deliberately to indicate flow is of gaseous material, not a terminology requirement, just for convenience). 

For gaseous flow, in the turbulent range, a 90 degree elbow is often modeled as having an equivalent length of 10' of straight duct as a shortcut for calculations for typical ductwork systems.  Most likely this is what you meant, that still is not directly related to mixing, but to duct friction.  In fact, per the ASHRAE duct friction database, at approximately 140 CFM in a 2" diameter duct  we are clearly in the turbulent range at approximately 6,400 FPM flow velocity.  Unfortunately the database does not give friction ratings for ducts that small, but at an equivalent flow velocity for a 3" duct, the static pressure loss for 100' of 3" straight duct is 22.5 inches WG, and for a 90 degree, short radius, smooth elbow, is only 1.13 inches WG (or the equivalent of only 5' of straight duct).  Rules of thumb aren't always applicable to unusual system requirements.

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Posted (edited)
1 hour ago, Latticino said:

Admittedly the most common usage is for standard weight pipe, which is schedule 40 up to 10" diameter.

Which is useless unless you have a certified welder.

 

1 hour ago, Latticino said:

black steel pipe

I agree. People use what ever they want to. 
For instance my pipe trades manual calls it "steel pipe", and so does my code book.
Piping needs to comply with ASTM A53/A53M or ASTM A106.

Propane needs to be at least sch 40. anything over 125 psi (note it is not diameter) needs to sch 80.

Keep in mind you can also use copper, plastic, stainless, galvanized, corrugated etc. 

But we all know that both of us can reference a code book. I assume that is what you are referencing? If not it is what you should be referencing.
 

1 hour ago, Latticino said:

including schedule 10 and schedule 80

10,20,30,40,60,80,100,120,140,and 160

But is this a tail wagging contest? Keep in mind minimum SCH 40 for propane. Code book (Canada) specifically references sch 40 and Sch 80.

 

1 hour ago, Latticino said:

Typically equivalent feet of pipe is a measure of pipe friction, not turbulence. 

I agree. It is friction, and not turbulence. I used that as a frame of reference.

 

1 hour ago, Latticino said:

Unfortunately the database does not give friction ratings for ducts that small,

As some point you can switch to fluid dynamics. Also, high pressure changes everything.


 

 

1 hour ago, Latticino said:

For gaseous flow, in the turbulent range, a 90 degree elbow is often modeled as having an equivalent length of 10' of straight duct as a shortcut for calculations for typical ductwork systems.  Most likely this is what you meant, that still is not directly related to mixing, but to duct friction. 

I agree. I did not know what size pipe he was using. 

A gas fitter uses pressure rating, sizing BTU, Calorific value, and pressure losses to make sure that the gas supplied is going where it needs to be.
A sheet metal worker can determine flow and turbulence (not of gas lines though. You can get high velocity duct at 2").

An engineer or equivalent would determine fluid dynamics for appliances and advanced pipe dynamics.

I do gas, duct, and refrigeration. 
I am not an engineer. Nor do I claim to be.

Turbulence isn't even what would be nice. 

Laminar mixing is what would be nice.

Laminar2.jpg.db2ed48c5bba39526478f95acf2ca08a.jpg

Edited by Mod34
Commercial link removed per TOS

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matrixiam;  I am confused, if you know so much more than us about all this stuff; why do you keep asking us about it?  My first thought was that you were trying to sell them and were using "grey" marketing.

(And do you have a video of a 90 deg pipe flow with two gasses of differing densities?  That one seems to be all one density and so may not  tell much about the issue we are interested in. )

Now a question that would be interesting would be: could the "baffles" be printed in plastic and inserted in a plain piece of pipe?  Would the riffles on the printed baffles be a plus or a minus?

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1 minute ago, ThomasPowers said:

matrixiam;  I am confused, if you know so much more than us about all this stuff; why do you keep asking us about it?  My first thought was that you were trying to sell them and were using "grey" marketing.

I work with 1st year apprentices that offer good insight all the time.

I am not a blacksmith.

People keep coming up with attacking/conflicting info as if the create some measuring contest for some reason. From day 1 I was jumped on. I have already had a discussion with the admins about this.

I have no problem discussing other things like what people call BIP or what sch to use. But those are just references that people seem to be throwing out to have a battle of wits.

The correct answer is the correct answer no matter whom it comes from. I am wrong all the time.

Nope I am not selling these things. But, we can keep attacking me. I simply asked if people knew of a good way to make them. I am learning as you guys are about them. I literally just found out about them before the post. But I can read just as well as you guys can.

 

6 minutes ago, ThomasPowers said:

And do you have a video of a 90 deg pipe flow with two gasses of differing densities?  That one seems to be all one density and so may not  tell much about the issue we are interested in. )

I don't have any videos. Sorry. At this point it seems like you're baiting me for some reason. If you want one, make one.
 

 

10 minutes ago, ThomasPowers said:

Now a question that would be interesting would be: could the "baffles" be printed in plastic and inserted in a plain piece of pipe?  Would the riffles on the printed baffles be a plus or a minus?

As long as they didn't react with the oils in the gas and the pipe. That is what most of the companies that are selling them for hundreds of dollars are doing. Metal would be better though.





 

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matrixiam, it may not be your intention, but a lot of this comes across as someone who is asking a question for the sole purpose of demonstrating that they have superior knowledge/understanding of the topic.  We get that from time to time, so the guys who have been around for a while tend to be a little guarded when things seem to be going that way.

In general we are DIY types of folks and we try to keep most of the construction materials and methods to something that people are likely to already have or can easily obtain.  If something requires a high level of technical expertise or specialized tooling to produce we are probably going to recommend purchasing such an item from someone who specializes in that area.

On the other hand we are always looking for new and easy ways to improve our understanding and our DIY projects.  If you come up with a way to improve the air/fuel mixing on a blown burner which can be made with tools, materials, and skills that are common we are definitely interested in whatever you come up with.

Discussing conflicting information in a civil manner is not attacking.  Just like you are asking questions and doing research to further your understanding, the people here whose understanding or information is different than what you provide will also ask questions about what you presented to further their own understanding and make sure whatever is on the site is accurate.  It's just peer review.

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I am in no way attacking you, just trying to clarify for others on the forum.  You clearly have your own ideas and aren't exactly open to dialogue.  I'll refrain from commenting on your posts in the future.

However in this case I think we are certainly on the same page, just using slightly differing terminology. 

In the first case I was just trying to illustrate to the members at large that BIP does not necessarily refer to sch 40 pipe, but essentially any thickness malleable steel pipe.  I can certainly reference codebooks and ASTM standards as required.  Typically I believe the applicable standard is ASTM B31.9 (Building Services Piping), which most building codes reference.  Please note that I was referencing Natural Gas/Air mixers, not propane, but that there was nothing in my initial statement about black iron pipe that mentioned what material it transported.

Incidentally I don't think you mean a "tail wagging contest" the common saying is a little different.

BTW, I am an engineer and certainly could do the fluid calculations, but don't have the time or inclination for what is essentially a free service here.

A couple of further points from my experience (solely my opinion, and to be taken as such without external reference corroboration):

  1. You most likely don't want laminar flow mixing, as one of the key limitations with most home made burners is getting an appropriately sized blower to overcome the system pressure.  Multi-outlet burners add some pressure loss, and laminar flow typically increases duct friction over turbulent flow.  Also to keep the mix in the laminar range would require much larger piping, which would likely be cost prohibitive.
  2. You will also get a significant amount of friction from your proposed turbulent spiral mixer. 
  3. I'm not certain there is a need for an enhanced mixing device for a multiport burner.  Have you experienced any mixing problems in the ones you have operated?  I ran them for well over 15 years with no problems.  I think the back pressure at the chamber just before the outlet and the rapid expansion of the pipe into that chamber provided enough mixing for me, but YMMV.
  4. In my experience gas fitters install the pipe sizes indicated on the design drawing construction set.  They certainly may use their experience to question the engineer's pipe sizing if it seems grossly out of sync with the application, but rarely are responsible for the final pipe size.  Of course I typically deal with larger commercial, residential, or industrial facilities, so your experience may differ.
  5. Code book sizing of gas lines is intentionally conservative.  However, as engineer of record I still use these for construction projects as we are required to comply with code.  Construction code books don't necessarily apply to design of parts of a piece of equipment.  They may have some crossreference, but more typically I believe that national or international standards like UL, ASTM, etc.  However I haven't officially designed appliances for well over 30 years, so things may have changed.
  6. 1 hour ago, thematrixiam said:

    Which is useless unless you have a certified welder.

    I don't understand this comment.

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Just wondering if this would be a noticable difference vs. the way thousands of blacksmith already have had there gassers plumbed.

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Industry standard terms for blacksmiths are not always the same as standard terms for fitters, welders, electricians or the HVAC industry, even though all of them use one form of pipe or another. I feel a smart person should know that.

I have never heard of the term BIP before now. and I have been an Industrial electrician for over 35 years, smith for over 25

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4 minutes ago, Steve Sells said:

Industry standard terms for blacksmiths are not always the same....

On top of this standards from one city/state/province/region/country differ greatly

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