atmospheric burners? (long)

updated fri 28 feb 97

WardBurner@aol.com on fri 31 jan 97

Jim & Suzanne,

The B-3 is not a wimp, it's just got a wide range of operation, but you're
only operating it on the low end with natural gas.

The output of a Venturi is primarily determined by the throat diameter (the
skinniest part of the flame tube). The smaller this diameter is, the lower
the low end BTU output will be. This is because a certain amount of gas has
to mix with a certain amount of air. When the throat is small and the
pressure low, only a small amount of gas/air can get through. If you had a
inexpensive burner, like the Gas Appliance MR750, you would have a burner
that puts out about 75,000 BTU's at 7" natural gas. Why does this far less
expensive burner put out twice the BTU's on 7"NG? Bigger throat diameter, so
it can use a bigger orifice. Now, I know you're thinking, "why in the world
would I ever buy a expensive burner like the B-3?" The B-3 is a far better
burner. Even though it's low end is 29,900 BTU/HR, it's high end on 20 PSI
propane is 246,000 BTU/HR. You'll never put that much through a MR750. This
is where the throat diameter helps. Along with it's long length (realitive to
the throat diameter) this burner can pull in more primary air than the MR750
or other less expensive burners. So, why are the Ransome's so much more
expensive? (I currently sell the MR750 for $42.00 vs $175.00 for the B-3) The
MR750 is a single piece casting of lesser quality metal. It is very coarse on
the inside, which creates much more turbulence. Because of this turbulence,
the motion of the gas down the tube is not as smooth and forceful, resulting
in less air being able to be pulled into the burner. The higher the pressure,
the worse this situation becomes. The B-3, on the other hand, is made with
much tighter tolerences and better metal. The inside of the Venturi tube is
much smoother allowing better motion of air/gas. Also, the the B-3 is cast
from three separate parts; the body, retention head, and the baffle plate.
All of these pieces are machined and the baffle plate is welded inside the
retention head. The retention head is threaded onto the body. All this costs
money.

To answer some more of your questions;

The burner can go "faster" (higher output) by increasing your pressure. This
is usually not possible with natural gas. Or you can switch to high pressure
propane (1-20 PSI). If you switch to propane, you'll be needing a new orifice
for the burner. (I can advise and supply you with the proper one).

It already is a very efficient burner. Efficientcy refers to the ability of a
burner to fire as close as possible to "on ratio". This means the proper mix
of air and gas over a wide range. Output and efficientcy are two different
things.

A different nozzle will not change the output and could make things worse at
hgih pressures. Removing the air shutter spin plate will just restrict your
ability to reduce.

Marc Ward
Ward Burner Systems
PO Box 333
Dandridge, TN 37725
USA
423.397.2914 voice
423.397.1253 fax
wardburner@aol.com

the new catalogs should be back from the printer in about 5 days.

In a message dated 1/29/97 9:45:33 AM, Jim & Suzanne wrote:

<only puts out thirty thousand BTUs: It is setting here on my desk and the
catalog from Ransome is open to page one and it says for inches of
natural gas it is a wimp? What can I do to make this burner go faster? It
looks like a racer, can it be made more efficient? What would a larger
orifice due? Or what happens when the end plate is removed? Or a different
nozzle?
These burners look like the burners under a old Alpine with atmospheric
burners. They are about the same size and shape. What have I missed? If you
would explain this, I would be able to get on to the next mystery. I would
like to use them on a kiln I'm building out of a castable mix, found on the
ceramic web, then gopher.
Any input on this to me, or the group, it may be of interest to others as
well.
Thanks
Jim & Suzanne @
TerraShire Studio>>