[TheForge] burner question

Mon Dec 1 20:59:06 2003

First I want to thank Tom for a much better description of what's happening
in inducers than I've been able to provide in the past.

There are two basic types of inducers being used as burners right now or
perhaps I should say variants.

The first and most common type is called a "linear inducer". These are
recognizable as the air intake is inline with the bore. The "Reil, EZ and
Bunsen burners are all "linear" inducers.

The other type is known as a "jet ejector" inducer and is recognizable by
the intake ports being at a 90* angle to the bore and jet. The "Side arm,
Mongo and Fisher" burners are examples of jet ejectors. (The term "jet
ejector" is the term used to describe this type of inducer in the material
I've read but may be a "brand" name that came to common usage in the
industry, like "refrigerator".)

Anyway, to make a linear inducer work well enough for a decent forge burner
without an intake bell (it should really be a trumpet flare but bell
reducers work well enough) it requires as Tom stated a small jet and high
gas pressure. It will also be very temperamental. Tom's laid out the hows
and whys of intake venturis very well and I won't repeat any of it.

A 1:12 increasing taper on the entire length of the tube is industry
standard as it's the most efficient. In addition to slowing the gas velocity
it decreases pressure in the device increasing induction at the intake.

What Bob describes is a "jet ejector" and it's pretty common for lthem to
not have intake bells, they're far more efficient than linear inducers. Jet
ejectors develop a very strong vacuum and at industry ideals produce
inductin ratios in the 27 to 29:1 range, depending on the gas or liquid
being supplied to the jet. At industry ideals a linear inducer produces a
weak vacuum and output ratios around 19:1 with far less variation due to gas
or liquid through the jet. As jet ejectors produce a strong vacuum at the
intake the need for a bell is minimal and at the reduced efficiencies
necessary to make an efficient burner an intake bell is unnecessary.

In industry, burners are primarily linear inducers as they have the capacity
to make them to the higher tolerances necessary to produce efficient flame.
As a home built device it's harder to hit the ideal 1:17.5 propane to air
ratio for a neutral flame with a linear inducer.

In industry jet ejectors are frequently used to produce large volumes of
vacuum and can be found on machines like the big vacuum trucks used to clean
storm drains. Not all sewer suckers use jet ejectors but many do. Anyway
with an ideal induction ratio of 27:1 it's much easier to get the 17.5:1 air
to propane ratio for an efficient burner. Also as it produces a stronger
vacuum and output flow it's much more stable.

The "T" burner I'm now using can be seen on Photoaccess under forges and
hoods (I think). The little dog is Pocket. <grin>

Thanks for the plug Larry even though I only adapted an existing device.
<grin>

Frosty
------------------------
If it ain't forged
it ain't real.
Wrought iron is.
The FrostWorks

Meadow Lakes, AK.

----- Original Message -----
From: <[email protected]>
To: <[email protected]>
Sent: Monday, December 01, 2003 9:23 AM
Subject: Re: [TheForge] burner question

> Andy,
>
> There is a drawing
> here...http://www.blacksmithsjournal.com/forgeinfo.html
>
> There is no flare on the end of the burner that goes into the forge.
> The outside end is a piece of pipe that telescopes over the main burner
> pipe. The gas goes in the end. There are cut outs on the burner tube
> and the telescoping cap that allow for air adjustment.
>
> Bob
> __
> On Monday, December 1, 2003, at 12:16 PM, Andy Vida wrote:
>