help with drill size for burners

[jrgpots]

I have built a 13.5 cubic foot downdraft  with 9 inch walls of K26 IFB.  The floor has 4.5 inch IFB + 4 inch high silica refractory brick and a 2.5 inch heavy duty hard brick layer.   The sprung arch is 7.5 inch IFB + 2 inch kaowool.  I think it should require 225,000 BTU/hr.   It's designed with 2 side burner at the back on either side of the chimney.

I have 2 old atmospheric burner designed for propane.  Each burner has three #52 drilled holes.  At 7" WC natural gas it should produce 54,000 BTU/hr.    

According to Ward burner charts,  if I keep 7" WC pressure, I would need to drill out the three holes with a 36 drill bit size.  Each burner would then produce about 117,000 BTU/hr.

CALCULATIONS:   3.3072(pressure funtion) x 11,796.84(orifice funtion) x 3 holes in each burner = 117,000 BTU/hr output 

Does this sound right?

 

[Mark C.]

I thought that you where getting higher presume-thats what the less than 2 inch pipe run was about? I'm confused

As to the hole size-Do you have spare orfices/ I would drill the smaller and work up if needed.

Hpw long ios that pipe run and what size pipes is it?

 

[Bill Kielb]

7 hours ago, jrgpots said:

CALCULATIONS:   3.3072(pressure funtion) x 11,796.84(orifice funtion) x 3 holes in each burner = 117,000 BTU/hr output 

Does this sound right?

 

Use an orifice table. Since it’s an area thing, as in squared, it’s not linear as Well as output varies with the cube of pressure I believe. Might be squared, anyway just look up pressure and size for a single orifice in table. Venturi  burners work better with a single orifice anyway.. I would definitely upsize them as tested and needed as well. Drill back to front as well.

here is the table,   https://ssl.ca/wp-content/themes/sinclair-supply/pdf/Gas-Orifice-Capacity-Chart.pdf .

for safety I would keep this to 7 inches mas anyway.
 

 

[jrgpots]

11 hours ago, Mark C. said:

I thought that you where getting higher presume-thats what the less than 2 inch pipe run was about? I'm confused

As to the hole size-Do you have spare orfices/ I would drill the smaller and work up if needed.

Hpw long ios that pipe run and what size pipes is it?

 

I had the burners from the Minnesota flat top staring at  me.   They were saying they were free and wanted to get into the heat of things.......Atually, The power burners are a bit pricey.   Anyway, I couldn't sleep last night so I  did some calculations.  I probably will use the power burners at higher pressure.  I just have to get used to pulling the trigger on the price tag.

Jed

[Mark C.]

Jed my small 12 cubic updraft runs on six small venturi burners-the final pipe size is 1/2 inch-I think your two burners will work fine for 13 cubic foot. Thats a small kiln. I would try those  1st as you own them-do you some height with a chimney to make for some draw?

I'm now confused -you own power burners or venture natural draft burners?

can you send me photo of yoiur burners?

[jrgpots]

I own venture burners, but was going to buy/use power burners so I would not need as high of stack.  That being said, I have a lot of left over bricks from the old kiln I tore down.  The bricks are free at this point.  I will take a pic of the burners I have when I get home this evening.  

[Bill Kielb]

2 hours ago, jrgpots said:

 Anyway, I couldn't sleep last night so I  did some calculations.  I probably will use the power burners at higher pressure.  I just have to get used to pulling the trigger on the price tag.

I don’t get it, natural gas power burners usually run inches of pressure, not PSI. A 3/16 drill gets you 126000 btu each. What am I missing? Power or Venturi, you will need A 3/16 orifice.??????

[jrgpots]

These burners are not venture shaped.  They are more like stainless steel weed burners.  I am in the process of replacing the thermocoupler and copper tubing to the pilot burner. They were bent out of shape.  Are they worth my time or should I buy a ward system?

[jrgpots]

This is the current burner tip with three 1/16 dia drill holes.  It can easily be changed to a single 3/16 drill hole.  

[Bill Kielb]

40 minutes ago, jrgpots said:

This is the current burner tip with three 1/16 dia drill holes.  It can easily be changed to a single 3/16 drill hole.  

Hahah, I have seen worse! How do they perform and at 7” is the flame reasonably blue? I assume you have used them on something in the Past. Three holes will get you there as it’s all about how many cubic feet at about 1000 btu per gets there. If the flame is reasonable and can draw enough oxygen to be reasonably blue at upper pressures I would try them as drilled. If they can’t entrain enough air to run clean then yes, replace them. Power burners still will be rated at 7” of gas so 100000 btu still gets a big orifice. With power burners you will need to manage your primary air in reduction a little different than Venturi but usually provides more flexibility. I like power burners so that would be my first preference. Nothing says you can’t try these out though.  Either way, if my memory is correct you need a regulator that goes from 2# - maybe 11”. Something like that.

[Mark C.]

The inchs per pound are 7 inches =1/4 pound-so you can work that up if needed.1/4 pound is what house natural gas pressure is =7 inch water column . The home appiances step  it down from there like water heater or gas range.

Those burners are one of a kind homemade-they do have a pilot burner which is great

they also had a pilot lite (the small tube is missing) valve. Sounds like you are repairing them.

I would try the burners-how big was the kiln they came from (that I sent you the info on )that you took down(I forgot that info as it was to long ago)

You have zero to loose trying them except a few $ and some time. I would try them and see what they do.

[Bill Kielb]

1 hour ago, Mark C. said:

The home appiances step  it down from their like water heater or gas range.

 

Natural Gas
Your approximation is good! 27.72 inches = 1PSI (2.31 feet per psi is how it’s stuck in my head). Just for information, Here in the States most appliances have their own regulator to drop the final pressure to 3.5 inches.

[Mark C.]

Bill when I got a gas main run up my hilll 1,000 feet from main line at bottom of hill. The crew showed me how to adjust my regulator on a large Spruage 1000 gas meter. You will see this size  meter at any large resturant . They gave me a water filled inches device to adjust the meter (this would never be done theas days by any utility company)I gave them a mugs.This was 1973

since then they have replaced my meter 3 times now its a bit smaller-more effeciant -same large regulator .

the 7 inches=1/4 pound is eched in my brain from that day. For all intent 1 lb pressure is 28 inch water column inches not splitting hairs.

As a diver with two scuba compressors and 20 tanks (I'm a  ceritifed scuba tank inspector as well) gas and pressure is what I have be using for another 35 years.Partial presures and some nitrox  mixes are all pretty standard stuff.My usual presures are 3,200 PSI some 3,500 and some stell tanks ar 2,400 PSI.

this low pressure natural gas stuff is easy for me. Now recalling orfice size I choose to keep my mind free of that stuff. Once you get the right orfice 40 years can slip by.

On another note this past year I leaned that yoiur orfices  can get slowly glogged up over time with impurities in the natural gas and hand reaming them out can work wonders with the right size letter drill (I use letter drills for all orfice work)Paul Giel turned me onto this info  via a friend and he was right my friend and myself cleaned ours and the kilns are working much better. Small factoid .Only use your hand not a power drill to ream them out.

[jrgpots]

2 hours ago, Mark C. said:

 

I would try the burners-how big was the kiln they came from (that I sent you the info on )that you took down(I forgot that info as it was to long ago)

You have zero to loose trying them except a few $ and some time. I would try them and see what they do.

  These two burner fired a 60 cubic foot minnesota flat top using propane.  I fired them up with propane and they worked great.  Then the copper tubing got flattened . So I am  repairing them.   I have never fired them up using natural gas.  I will drill them out for natural gas and find the best pressure they run at.   To run the test, I will need to get a low

pressure regulator

Jed

[jrgpots]

5 hours ago, Mark C. said:

 

....On another note this past year I leaned that yoiur orfices  can get slowly glogged up over time with impurities in the natural gas and hand reaming them out can work wonders with the right size letter drill (I use letter drills for all orfice work)....

I deal with people having clogged orifices all the time.  I don't recommend power drills either.  Milk of Magnesia or fleets enemas are much more effective......lol

 

Jed

[Hulk]

Oh dear.

Good tip on the hand reaming; if lotsa clog, start with a smaller bit and work up to the orifice diameter.

As to the doctoring, perhaps a glass of water, then celery juice, followed by strong coffee and a few flights of stairs. A dear man I once worked with swore by a few drags onna cigarette. Fresh coconut, oatmeal...

[Bill Kielb]

14 hours ago, Mark C. said:

On another note this past year I leaned that yoiur orfices  can get slowly glogged up over time with impurities in the natural gas and hand reaming them out can work wonders with the right size letter drill (I use letter drills for all orfice work)Paul Giel turned me onto this info  via a friend and he was right my friend and myself cleaned ours and the kilns are working much better. Small factoid .Only use your hand not a power drill to ream them out.

Must be tough on gas valves and regulators eh? Exterior parts do corrode. And often spiders really like them as well. Also a very good reason to properly pipe as in dirt legs and pipe sealants.

[Magnolia Mud Research]

Use clean black iron pipe, not galvanized pipe.  The odorizer in the natural gas will, over time, react with the zinc  and produce  flakes.  

[Mark C.]

16 hours ago, jrgpots said:

  These two burner fired a 60 cubic foot minnesota flat top using propane.  I fired them up with propane and they worked great.  Then the copper tubing got flattened . So I am  repairing them.   I have never fired them up using natural gas.  I will drill them out for natural gas and find the best pressure they run at.   To run the test, I will need to get a low

pressure regulator

Jed

I think the low presure regulator may be had at RV stores ?I'm guessing 

On your burners did you use forces air with them(power burners )I eall thats what folks did with those homenade ones.I'll checkmy old studio potters mag on that.Lou Niles did that write up long ago.

[Bill Kielb]

3 hours ago, Magnolia Mud Research said:

Use clean black iron pipe, not galvanized pipe.  The odorizer in the natural gas will, over time, react with the zinc  and produce  flakes.  

Flakes for sure, dirt leg is important. 2009 IRC got rid of galvanized and natural  gas  zinc issue (I believe, unless it’s back) . Still many local codes don’t allow it. Clean assembly, dirt leg, no moisture very important, don’t mix black and galvanized, even more issues.

2009 IRC G2414.4.2 (403.4.2) Steel. Steel and wrought-iron pipe shall
be at least of standard weight (Schedule 40) and shall comply
with one of the following:

1. ASME B 36.10, 10M;
2. ASTM A 53/A 53M; or
3. ASTM A 106.
   Commentary: Steel pipe must be Schedule 40 or heavier, must comply
   with one of the listed standards and can be black
   iron or galvanized. Contrary to popular belief, natural
   gas does not adversely react with the zinc coating on
   galvanized pipe."