Burners 101

[Mikey98118]

So, it occured to me that home-made ribbon burner builders may have two problems: Less than total combustion; and back firing, once their plenum chamber heats up fully. Not every burner is going to have both problems; some may have no problems. But it is nice when the solution to one problem reduces or cancelled the other.

Fuel rich flames, whether one central flame or multiple flames in a burner head, calls for a little secondary air. If that air is flowing into the forge through a gap between the burner head and the forge shell, it is going to help cool down the burner head. What do you think, Frosty?

[Frosty]

I remember having some smiths out for a little hammer in and while the old "experienced" smiths were standing back talking about it not being possible to weld under a naturally aspirated burner, I slowly turned up the psi on a young man who wasn't paying attention to his project. The guys took a closer look when the boy drew a piece of 1/2" sq from the forge with about 1 1/2" of sizzling sparkler and the forged point dripping off the edge.

Gun or NA have their up and down sides but when it gets down to brass tacks a burner works by putting X amount of flammable mixture in a space per second. PERIOD. Everything else is interesting but not substantially different.

Ribbon burners are a different cartload of things to consider. The burner (orifice) block over heating was my hard to deal with issue. I couldn't turn the psi down very far without the block overheating, it required a good flow to cool it and prevent the fuel air flow from reaching it's flash point OR more likely it's flame front falling below flow velocity. 

Even with the input pipe being in line with the outlet ports I never saw differences in fuel air mix between outlets. Different flame lengths oh heavens yes but the apparent ratio appeared consistent. Once I rotated the inlet port 90* so the flow into the plenum impacted the far plenum wall, the flames evened out almost completely. I was a little surprised until I thought about a while that the longer flames were centered and at each end. They didn't gradually get shorter as the distance from the intake increased, they formed more of a sine wave looking whatchamacallit. The flow was running along the top of the plenum away from the outlets until it hit the ends where it turned towards the only route of escape the outlets. 

Anyway, What time the fuel air flow spends in the plenum is violent turbulence and only smooths into a laminar flow IN the burner block outlet. No chance of unmixed fuel air mix, it it's wrong they're ALL wrong.

To your question. If there was unmixed fuel air reaching the outlets there would be rich and lean flames in whatever pattern the ill-mixed flow reached them. In answer, sure probably if they weren't too different.

It brings to mind the old saw. If you have one problem you have a problem, if you have two they might cancel each out.

Frosty The Lucky.

[Mikey98118]

9 hours ago, Frosty said:

It brings to mind the old saw. If you have one problem you have a problem, if you have two they might cancel each out.

Yes; that is the hope.

[Frosty]

Unfortunately it doesn't work as often as I'd like and I have to keep adding problems until one finally does. <sigh>

Frosty The Lucky.

[Mikey98118]

On 9/9/2022 at 7:46 AM, Frosty said:

Not to intrude on a thread that's being so well served by Mike but the length to diameter of jets is a function of the ratio not the specific dimension. That means when you're talking about that small a diameter orifice a much shorter length makes a laminar flow in the propane stream. 

I should have picked up on this far earlier, but the point Frosty is making is that long enough to create laminar flow is all that is desirable in small gas orifices, due to build up of friction in any additional length.

3D printer nozzles, MIG contact tips, and even gas orifices used in gas appliances, all have larger entrance diameters than exit diameters. Even though they streamlined to maintain good flow, the gases that pass through these internal shapes will spin, in inevitable consequence to this constriction. So, gas exits are made by through-holes, to create a certain amount of internal friction; this stops the rotation, allowing laminar flow. Laminar flow does a better job of air induction.

[Mikey98118]

Yeah, yeah; but why do MIG tips have through-holes then, huh? While they aren't designed with gas flow in mind, by happy coincidence, they all need some distance through a thru-hole to help straighten the MIG wire, which is curved somewhat by the drive rolls. If not straightened, the wire will wonder around, making a straight weld bead impossible.

[Frosty]

Why . . because they aren't Tig tips?

I've seen too many beads where straighter wire didn't work so well, run a few myself.

Does lend itself nicely to making a laminar flow though.

Frosty The Lucky.

[Mikey98118]

3 hours ago, Frosty said:

Does lend itself nicely to making a laminar flow though.

Yes; MIG tips have been a very happy burner discovery over the years. I only hope 3D printer nozzles work out half so well in small burner sizes

Hoke torch tips are also serviceable for burner sizes between 1/8" to 1/2", but aren't cheap or as easy to find as printer nozzles, outside of the USA. On the other hand, if you want to build a very nice burner, they are still worthwhile.

[Frosty]

They sure beat drilling a hole in a piece of pipe don't they? 

I'm sure 3D printer nozzles and Hoke torch tips will work out very well, it'll just take a little tweaking for home builds is all.

Frosty The Lucky.

[Another FrankenBurner]

I have moved over to 3D printer nozzles with my burners.  Higher velocity, higher induction, higher output per pressure. 

I also like that they are brass so they are easier to turn as I braze them into ¼” stainless brake line.

I’m not suggesting they are better.  They work for me. 

[Mikey98118]

17 hours ago, Frosty said:

They sure beat drilling a hole in a piece of pipe don't they? 

Good one, Frosty. We have indeed "come a long way baby.

 

11 hours ago, Another FrankenBurner said:

I have moved over to 3D printer nozzles with my burners.  Higher velocity, higher induction, higher output per pressure. 

Good solid information, AFB.

 

[Mikey98118]

It's happening right under our noses

So, some guys want to just use a reducer fitting as their burner's flame retention nozzle. Sometimes this even works out pretty well.

Some guys prefer fan-flown burner systems, and IFI members have reached a consensus, that beauty is as beauty does. In other words, this burner's only limit is how well it is designed and constructed, and naturally aspirated burners are not necessarily better than fan-blown. This view is just as true today as back when we were saying that naturally aspirated burners can be just as good as fan built, some twenty odd years ago 

And some guys are mounting drilled stainless-steel strainer plates from faucet fittings into pipe reducer fittings to successfully create multi-hole burners from fan-blown burners; without the expense of Gilbert burner heads, or the work to build ribbon burners. Cheap and easy will always be a strong draw. As with every new idea, these burners are pretty crudely constructed. I predict that by next year, a second wave of better built versions will be the latest thing, which "everyone" is talking about, because, even when properly built, they are still far less work than ribbon burners. On top of that, they are easily scalable, larger or smaller;  and this last part isn't a passing point.

I say good! Bring them on. Every new kind of burner gives the forge builder more choices.

 

[Mikey98118]

If ready made drilled stainless-steel plates are available by repurposing faucet parts, why describe this method as "crude"? Because these plates are very thin, which means that they will oxidize away in a snort time.

Fortunately, stainless-steel plates, which are 1/8" to 1/4" thick can be purchased in a variety of diameters, online. Drilling your own multi-flame gas orifices is well compensated by having your flame retention nozzle last the expected amount of time.

[Mikey98118]

Will these multi-flame retention nozzles work on naturally aspirated burners? Yes, but you will probably need to do a fair amount of experimenting to get them to work properly. Such flame retention nozzles will work most easily on fan-blown burners. I would suggest small squirrel cage type computer burners, since you simply want to match the right amount of positive pressure input at your burner's entrance to the right amount--no less, but no more--than is needed to push the gas/air mixture out of multiple gas orifices at the end of a pipe reducer fitting; this fitting is serving as a very small plenum chamber, in similar manner to such chambers in ribbon burners and Gilbert burner heads.

1 minute ago, Mikey98118 said:

I would suggest small squirrel cage type computer burners,

This should read " I would suggest small squirrel cage type computer fans,"

[Mikey98118]

Speaking of ribbon burners, I ran across a site for a commercial ribbon burner product. I do not recommend their burner heads, but their method of diffusing the incoming air/gas stream may be instructive for some.

Apollo Ribbon Burner

[Mikey98118]

Soldering copper, brass, & stainless steel

Soldering uses the lowest temperatures of all thermal joining procedures on metal, but soldered joints are weaker than those that are silver brazed; they are also less able to withstand elevated temperatures. Therefore, soldering is used here as a method for affixing mounting plates to funnel mouths, and funnel spouts into or unto mixing tubes, as an alternative to higher temperatures needed for silver brazing; it is also handy for soldering gas fittings together, instead of threading, or for soldering additional joints next to brazed joints.

Stay-Brite 8 silver solder (Silver content 5.5-6.0%; remainder tin) bonds to all ferrous and nonferrous alloys; it has enough elongation to successfully bond dissimilar metals (melting range is solid at 430 °F to liquid at 535 °F), so it has an extended flow range. Kits as low as $18 through Amazon.com.

    Silver bearing soft solders (essentially tin/silver solders) aren’t less expensive than silver brazing, whether you purchase them in kit form, or in a full one-pound roll in one of the better solder alloys. Premium prices are also charged for effective stainless steel rated flux (resin-based fluxes are not sufficient. Strong bases and mineral salts must be used in stainless-steel fluxes; these become even more potent at high temperatures. You could purchase four or five feet of (56% silver) brazing wire and flux through eBay, or down at your local jewelers’ supply for less than a one-pound roll of the better tin/silver solders (ex. Stay-Brite 8 is 94/6 instead of the more typical 96/4). Is the difference between cheaper solder and the expensive variety really worth the expense? When used for plumbing, usually not; for use in HVAC, or in burner construction, yes.

    But it would also depend on your personal abilities. If you want everything going for you when doing this work, the possible extra expense of brazing on stainless steel is inconsequential. If you are an old hand at stainless-steel soldering, or already have the solder on hand, needing only to buy the special flux, your savings can be significant. According to a few of its listings, La-Co aluminum flux can be successfully employed in silver soldering aluminum to stainless-steel mounting plates, and funnels.

    Tin/silver (Sn/Ag) solders adhere better, are about five times stronger, and have a much greater ability to elongate than tin/lead fillers; qualities that are critical for successfully joining dissimilar alloys with different rates of thermal expansion.

    A higher silver percentage in filler alloys will wet joint surfaces better than a lower one. Try to find five percent silver (95/5) rather than one of the cheaper two or three percent silver filler alloys (be sure to sand or power brush the S.S. parts before assembly). Silver/tin solders do not max out at five or six percent silver content. Johnson Matthey Metals Ltd. manufactures JM MP5; a 10% silver/tin/copper solder (flow range of 417 °F to 527 °F (214 °C to 275 °C); they also make JMM, a 25% silver/tin solder (flow range of 430 °F to 437 °F (221 °C to 225 °C).

    The potential for galvanic corrosion between soldered (or brazed) S.S. and copper or brass parts is quite low.

    Lower temperatures aren’t the only advantage to be found in tin/silver solders; some of these fillers tend to fall into the “capping filler” category; meaning they tend to form “weld” beads at the lower end of their liquidus range, and can bridge much larger gaps than silver brazing fillers used for sweating work. What advantage is that for you? A capping alloy is far less likely to end up plugging the capillary tube during construction of micro gas jet assemblies, because you can drill a tight-fitting tapered hole at the base of the tubing cavity, and enlarge the section above it that is to be filled with solder; capping alloys will also bridge some gaps.

Note: Lead is still commonly found in imported plumbing fittings, and 2 to 3.7% lead content is present in every form of brass rod (round, hex, and square). When joining S.S. parts to brass fittings (of unknown alloys), the joint area of the brass should be prepared with an appropriate etchant to remove possible traces of lead from part surfaces, before fluxing. This will improve wetting. Also, any lead content in the join will eventually be converted to lead carbonate by left over acids from the flux, weakening the joint. So, figure on compression to trap stainless steel capillary tube in brass fittings—not soldering or silver brazing (leave soldering and brazing for inserts in copper or stainless tubes).

    Stainless steel oxides can be abraded from part surfaces. Roughened surfaces also improve capillary flow during wetting. A certain amount of roughening (ex, with sandpaper, or stainless-steel brush), where part thickness permits, is helpful.

    It is especially important to remove the chromium oxides formed on stainless steel surfaces before soldering or brazing; otherwise, your flux must work much harder, and if you are silver brazing thin-walled parts (ex, dispensing needles), the last thing you want to do is use an over aggressive flux. #304 stainless-steel, like gold, can have a completely oxidized surface that is also quite lustrous. Oxidation of other metals is obvious, as it dulls and discolors them. Aluminum also quickly forms a much harder oxide layer, which melts at higher temperatures than the alloy underneath it.

    Copper can simply be wire brushed to remove oxides and provide a roughened surface.  Inner surfaces can be considered clean if they have just been drilled. Copper alloys bond well with most fillers. However, high temperature fillers can promote problematic formation of oxides within capillary tube; therefore, low temperature, fast flow fillers are recommended for brass or copper capillary tubes used as gas orifices. Even 95/5 zinc-tin filler alloys will work for this job, but the filler below can help you to avoid drawing the filler into the capillary tube via its bottom face (open end) during joining.

    Stay-Brite 8 is a tin-silver solder (94/6) used in refrigeration and air-conditioning (HVAC) work, produced by Harris Products; it can be used with low enough heat to avoid weakening the metal tubing being joined (also producing much less internal oxide buildup); it bonds with most ferrous and nonferrous alloys, including stainless steels, copper based alloys, and aluminum; it has excellent toughness in dissimilar metal joins, is highly resistant to vibration damage, and is a capping alloy (more effective in filling loosely fitted couplings); its 105 °F flow range is 430 °F to 535 °F (221 °C to 279 °C) Stay-Brite 8 is available from Harris Products online; it is also sold through some hardware stores; Avoid exposing a gas jet employing this product to overheating from chimney effects.

Note: Harris also makes a 4% silver to 96% tin solder they call Stay-Brite (not Stay-Brite 8); this is a eutectic alloy, with a melting point of 430 °F; it will not bridge gaps.

Recommended fluxes for tin/silver solders include:

LA-CO 22101 2 Oz Paste Soldering Flux; it can be successfully employed in soldering on S.S. and soldering S.S. to aluminum, and is recommended above all the rest.

Superior No.71 (paste) and No.78 (liquid) flux for Stainless-steels, high chrome steels, Inconel, nickel, copper, and brass.

Kester 817 Acid Flux is formulated especially for soldering to stainless-steels.

Harris Welco SCPF4 4 Oz Stay-Clean Paste Soldering Flux (paste form) for soldering  copper, brass, bronze, steel, galvanized.  

[Mikey98118]

 

Silver brazing tubes to S.S. funnels

Being able to silver braze available funnels to available tubing products is a great convenience. Unfortunately (even with sausage stuffing tubes added in), working with what is available in the market restricts your possible repurposing selections, and so the occasions when funnels can be directly pushed onto, or trapped within, mixing tubes are limited. Also, some funnels of superior size and/or shape only have spouts that are way too small for your purposes.

    A burner’s funnel section can be joined to its mixing tube by cutting off its small end, and mounting a coupling tube (into which a mixing tube can be inserted); although more confident builders will choose to join the funnel directly to the mixing tube on naturally aspirated burners. Coupling tubes are preferred on fan powered burners, because their gas assemblies are made more complex by the presence of fans. A short coupler makes the gas orifice easier to keep centered, while brazing a gas assembly in place, below the fan; it also permits quick access to the gas orifice for cleaning.

    Luckily, coupling tube connectors can be generally employed to ease powered burner construction. A short section of tube, made out of the same tubing used as the spacer ring between the burner’s flame retention nozzle and mixing tube, can be silver brazed directly onto the funnel after threaded holes are placed in its forward end, and its rear edge is beveled to closely match the funnel’s angle.

    This coupling tube replaces an original undersize funnel spout or opening (which is cut away before brazing, and any excess sheet metal protruding into the mixing tube is ground or power sanded away, after brazing (or soldering to aluminum funnels). Subsequently, funnel and coupler are secured, either into or onto the mixing tube, with short socket head set screws. The rear end of the mixing tube is beveled on its inner surface, to maintain good air flow.

   So, how short a coupling tube is short enough? The portion of  tube that extends beyond the funnel should be no longer than twice the mixing tube’s diameter, and not to exceed 2”.

Note: Not only does tubing come with plus/minus tolerances (between 0.002” and 0.005”), but it is not perfectly round, (although it’s generally more concentric than pipe). Metric tubing seems to be the roundest, and is usually seamless, BUT, if the millimeter diameters are followed with decimal measurements that don’t exactly match up with them, be quite sure to use the decimal measurements.

    When you are power sanding parts to create a close fit, do not forget to keep rotating them while checking how well they slip together. Before securing the coupling tube on the mixing tube with socket set screws, rotate both tubes, for closest fit.

    Remember to completely remove internal burrs and chase the screw threads as many times as required to ensure a smooth fit between coupling and mixing tubes; a round file wrapped with sandpaper can be a great help in removing internal burrs and deformations made by a tap in small diameter tubing.

You want a close fit between a coupler and mixing tube; this isn't only needed for good mixture flow. When the mixing tube is inside of the coupler, you must seal the joint to prevent gas leaks (with thread-locker or gasket sealant). If the mixing tube is outside of the coupler, or outside of a funnel spout sealant isn’t likely to be needed.

    Once you have the mixing tube cut to length, measure how long it and the funnel are together; Buy a long enough length of threaded rod from your hardware store, (or an online source) to extend comfortably beyond both funnel and coupler or mixing tube, with room to spare for nuts, a large washer for the tube end, and a drilled plate or board to cover the funnel’s large opening. This arrangement keeps the parts held tightly together, and keeps them from wandering out of axial alignment.

Procedure for joining thicker mild or stainless-steel coupling or mixing tube to thin S.S. funnel: Both tube and funnel are cleaned, scoured and fluxed before being secured tightly together with fender washers, etc., on a carriage bolt or length of all-thread, and placed on a level surface. Using a propane or propylene torch with a brush flame, mostly heat the thicker tube with the primary flame at least ¼” away from the parts. Only allow the secondary outer flame envelope to touch the part surfaces.

    Pass the flame back and forth along the joint. Once the flux indicates the correct temperature has been reached (black flux by bubbling; white flux by bubbling and turning clear), dip the filler onto the joint area, and heat the drop or so of silver braze filler with the torch, while allowing the flame to also heat the funnel a little bit; as you again pass the flame back and forth, the heated joint will suck the filler in, spreading it along the joint. Turn the parts to expose an area beside the one you just finished, and repeat this process, over and over until the entire joint is filled.

 Note: Make sure to buy threaded rod (AKA all-thread) that matches the size and type of thread in your gas tube nuts, so that you can use it to trap one of those nuts securely centered on the gas tube’s mounting plate, and then to make sure the mounting plate and attached gas tube are positioned centered and axially true to the mixing tube. Since one of these two nuts is a flathead rivet nut (AKA Rivnut), you can wrap it in tape, and use it to help to keep your parts centered while the other (flanged) nut holds the parts tightly together with a second fender washer, etc.

    When you silver braze pipe or round tube onto a funnel, it is important to ensure a very close fit for a good braze job, leaving a gap of no more than 0.005” anywhere you want the filler metal to flow. Take all the time you need to ensure the best possible fit between tube and funnel, that you can manage. It helps to finish the fit-up by placing sandpaper between the mixing tube and funnel, to finish matching their surfaces closely. Any convex curvature in the funnel wall will increase your work (but is likely to be well worth it). When the tube or pipe is a close fit, note how wide the area of contact has become; this is what caused all that extra work, and is also the reason why this joint will end up strong enough to serve. If your braze job ends up with gaps in it, consider closing them up with silver solder.

    If the funnel has no spout, use all-thread to trap the funnel and tube together, in an axially true position. If the funnel does have a spout, you may be able to wrap tape around it, to enlarge its diameter until the tube just pushes over it, to ensure that it will end up centered and axially true to the funnel, before laying out the funnel’s outside line.

    Grind or power sand a bevel in the end of the tube as close as possible to the funnel’s shape, and then scribe or ink an outer line where the two parts meet. Remove everything that hinders your view of the funnel area you are going to remove. Measure the widest section of the tube’s inner bevel, and add a little more distance to it; then mark points along that distance for an inner cut line. Cut away the funnel up to those points. Place the tube back on the funnel, and ink a line on the funnel where the inside surface of the tube meets it. Grind or power sand right up close to, but not touching, that line; this is to keep your finish sanding or grinding work inside the funnel to a minimum, after the brazing is done. But, a slightly smaller opening in the funnel than the inside surface of the pipe or tube, provides a ledge to help prevent the filler metal from making a mess; it is well worth a little extra grinding or power sanding afterward, to prevent that.

    Sand or wire brush the area that you want to braze, and then flux both parts; but only on the area where you want the filler to flow. Clamp all of the parts together, to keep them securely trapped in position during brazing. You will have to use a silver braze alloy with at least 56% silver content, and flux meant for use on stainless-steel. 65% silver filler is even better.

Note: Both soldering and brazing uses capillary action to move filler metal over part surfaces in the joint area; For the process to begin, filler metal must start combining with the metal on the surface layer of the part; this is called wetting. Without wetting, the filler metal will just ball up on the part surface, and drop off. Silver content in the filler alloy promotes wetting. Stainless-steel’s chromium content is why it requires a filler rod or wire with a high percentage of silver to promote wetting. Chromium is hard to wet, which is why 18:8 is easier to silver braze than 18:10 stainless.

[Frosty]

23 hours ago, Mikey98118 said:

Speaking of ribbon burners, I ran across a site for a commercial ribbon burner product. I do not recommend their burner heads, but their method of diffusing the incoming air/gas stream may be instructive for some.

Apollo Ribbon Burner

I didn't find anything about how they diffuse the flow in their burners but they don't seem to know enough to post a burner even close to being in tune. I was going to make the suggestion but couldn't find a contact link that wasn't an order form. I think they're probably "commercial" burners but only in a semantic sense.

Frosty The Lucky.

[Mikey98118]

Yup; I think that exactly all they are

The diffusing plate is a drilled part inside the screw fitting on their backs. I don't think this is necessarrily the best idea, either; it's just one more way to do things.

[Mikey98118]

Stainless steel capillary tubes are silver brazed into larger copper, or steel tubes, and MIG contact tips in much the same manner as a mixing is tube is to a funnel. Place heat on the thicker exterior tube or MIG tip, and allow heat to transfer through it onto the capillary tube. When the outer tube is hot enough, a small drop of filler alloy is deposited onto the forward edge of the outer tube and capillary action is used to suck the filler within the joint; next, move the flame to the opposite side of the tube and repeat the heating, if needed. The capillary tubes are silver brazed in a vertical position.

Flat rings (used as flanges) of brass or stainless steel, are silver brazed onto stainless steel funnels in like manner, with the parts in vertical position, so that the filler can run around a horizontal joint more easily.

    Silver braze fillers are stronger than solder, and therefore fine for joining parts at the rear of a burner (ex. funnels and gas fittings). However, no silver braze alloy can handle the elevated temperatures that burner flame retention nozzles are exposed to, even in the open air.

    The most common mistake when silver brazing stainless-steel capillary tubing into copper parts, including refrigeration tubing and MIG contact tips, is to make a loose fit-up. Because the copper outer part will expand more than the stainless-steel part, loose fits tend to become oversize, resulting in a poorly brazed joint. Instead, make your parts reasonably tight fitting, and expansion from heating will only open them up to the proper spacing. Don’t worry about fluxing the joint’s interior prior to heat. Provide enough flux to the joint’s exterior face, and the capillary tube’s exterior; heat will draw it into the joint.  

    It is desirable to keep peak temperature of the parts as low as is practical, and to keep the time that your S.S. parts are heated short; dunking the parts in water right after brazing is recommended. High silver content fillers (56% silver or greater) are recommend for stainless steel joins; they can be found at jeweler’s supply stores, and at some welding supply stores. Silver braze filler alloys are also available from numerous online sources, including eBay and Amazon.com. Try to find filler that flows around 1200°F (648.9°C) or less. You are basically looking for filler alloys that conform to AWS BAg-7.

Rio Grande carries five different temperature ranges of silver braze filler alloys: Extra easy; easy; medium; hard; and extra hard. Their version of easy-flow silver braze filler has a flow range of 1240 °F (671 °C) to 1325 °F (625 °C); it contains 65% silver, which is best for wetting. If you’re going to buy a stainless-steel filler alloy, it is best to buy its flux separate from the filler (rather than a braze kit).   

Silvaloy #355 comes in wire and ribbon forms, and flows at 1205ºF (652ºC); it is a recommended alloy for stainless steel work; use with Ultra Flux® or with one of the black fluxes recommended for brazing on S.S.

Alpha Metals AM53500 comes with its own flux in a small kit available for $28.61 from many sources including Amazon.com. The kit includes a fifth of an ounce of.029 silver braze wire (56% silver/44% tin) and a half ounce tube of flux.

Handy & Harmon’s Easy-Flo 3 is especially recommended by them for joining three-hundred series stainless steels; also, for joining tungsten carbide, beryllium copper, and aluminum bronze to steel; it is solid at 1170 ºF (630 ºC); liquid at 1270 ºF (690 ºC); maximum brazing temperature of 1400 ºF (760 ºC)  

Safety-Silv 56 flows freely at 1205ºF (652ºC); it is available as flux coated rod and in wire forms, and is often sold as a kit with Harris’s white flux.

Harris Safety-silv 45 (Ag 45%; Cu 30%; Zn 25%) has a flow range between 1225 ºF (663 ºC) and 1370 ºF (743 ºC); it is a capping alloy, which is able to bridge gaps. This alloy is used on copper and brass alloys, and on mild steel. I would not use it on stainless-steel, unless the surface of the join area has first been whetted with a higher silver content filler alloy.

Lucas Milhaupt EASY-FLO 3 is recommended by them for joining #300 series stainless parts to each other, even though it only has 50% silver, because it also has 16% cadmium; the remainder is 15.5% copper, 15.5% zinc, and 3% nickel; its plastic range is from 1170 °F to 1270 °F; while this range is not very broad, this filler is a capping alloy, and can bridge small gaps.

Cadmium bearing silver solder and silver braze fillers are available from Lucas Milhaupt.

Warning: Cadmium is a powerful wetting agent, but it is also toxic; if you work with it, use a powered exhaust vent inside your shop, or area fan (blowing the fumes downwind if you’re already outdoors) to remove toxic fumes from your breathing space. Wear a respirator rated for heavy metal fumes. Be very careful not to overheat the filler alloy; do not exceed its liquidus temperature. Also wear a respirator when sanding or grinding on surfaces that have been treated with a cadmium bearing coating, or grinding on a joint made with cadmium containing filler. 

Silver brazes containing phosphorus are self-fluxing on copper-to-copper joints, and can be used on copper to brass joints with common borax flux. However, their melting range is more than high enough to produce unacceptable amounts of oxide in gas jet parts; avoid their use for this purpose. Do not use phosphorus containing fillers on any of the ferrous metals, including S.S. (the joint will crack apart; either immediately, or soon afterward).

Handy Flux Paste is an active fluoride-borate white flux that begins to become molten and dissolve oxides at 600 ºF (320 ºC); it is fully molten and active at 1100 ºF (600 ºC), and provides protection up to 1600 º F (870 ºC); for brazing stainless steel, mild steel, nickel, copper and other nonferrous alloys. Cleanup the flux residue with hot water after joining. This product is recommended for use with very thin stainless-steel products, such as dispenser needles (which the more active black fluxes may dissolve the walls of). This flux can be ordered through participating welding supply stores, some plumbers supply, and HVAC dealers; also, from the online locations. Use with Easy-Flo (contains cadmium), and other (non-cadmium bearing) silver-braze fillers.

Note: While not as active as Handy Flux Type B-1 Paste, this flux can be more convenient to use in the kind of tight fits recommended for stainless steel capillary tube trapped within copper tubing and MIG contact tips, or within half-hard brass tubing. This is because it flows far more readily than black flux, so as to be sucked more easily into the joint; it also turns milky white, and then clear just before the parts reach the right temperature for silver brazing, helping the operator to judge correctly just when to apply filler alloy.

Harris Welco Stay-Silv Extra High Temperature Black Brazing Flux is an all-purpose high temperature silver brazing flux; it is particularly useful where large amounts of refractory oxides may form. Use this flux on stainless steel, and carbide alloys; active temperature range is 1050 °F to 1800 °F (566 °C to 982 °C); see resource list.

Wolverine Black Flux is active between 1100 °F and 1800 °F (593 °C to 982 °C); it is recommended for joining refractory metals (ex. stainless steel), and for extended brazing cycles. The flux is a water-based paste, consisting of potassium salts of boron and fluorine. This product can be ordered through participating welding supply stores (try Praxair first), and some plumbing supply and HVAC dealers.

Sure Flo Black Paste is a product of Lucas-Milhaupt, Inc. Black Paste can be used for brazing steel, high chromium stainless steel, tungsten, tungsten carbide, chromium carbide, copper, copper alloys, nickel alloys and molybdenum; active temperature range is 1050 °F (540 °C) to 1700 °F (926 °C). When heated this flux becomes very corrosive; post braze cleaning in hot water is necessary; if stored beyond normal shelf life, or an open container dries out, it can be restored by addition of water; it may also be deliberately thinned with water. This product can be ordered through participating welding supply stores, some plumbers supply, and HVAC dealers. The particular advantage of all the black fluxes is that they stay exactly where you put them during heating.

Handy Flux Type B-1 Paste a product of Lucas-Milhaupt, Inc. Handy Flux B-1 (boron modified) is especially suited for brazing high chromium stainless steels, tungsten, chromium carbides, and molybdenum alloys; it has an active range of 1100 °F (600 °C) to 1700 °F (926 °C). This product may be thinned with water. When heated this flux becomes quite corrosive; post braze cleaning in hot water is necessary. This product can be ordered through participating welding supply stores, some plumbers supply, and HVAC dealers.

Handy Flux Hi-Temp Boron Modified Paste for high temperature silver, copper, nickel, or stainless-steel brazing in the range of 1600 ºF (870 ºC) to 2200 ºF (1200 ºC), involving longer time or base metals with refractory oxides. This is a good candidate for oxy-fuel torch braze welding  the rear edge of SS nozzles to mixing tubes with nickel rod; it can be ordered through participating welding supply stores, some plumber’s supply stores, and HVAC supply dealers. The fumes from this product are toxic; work in a well-ventilated room and use an approved respirator to avoid the fumes. When heated, the flux forms a vitreous surface that should be removed with a sodium-bisulfate pickle.

[Another FrankenBurner]

That Apollo ribbon burner is meant to be air supplied with a 6 inch 440 cfm centrifugal inline fan.  A big fella. 

[Mikey98118]

I suspect that a little bit of positive pressure, provided by a small fan, may provide low cost insurance against, imperfect burner design. However, large fans only demonstrate the need to overcome really poor design. Plus, they are expensive, noisy, and can't be run from a small battery; ugh!

[Frosty]

It's obviously a gun burner, a NA running as rich as shown in pics couldn't blow hard enough to push flames that far off the burner block. I don't think so anyway, could be wrong.

Back when I was searching out all I could about multiple orifice burners I found a lot of pretty detailed pics and drawings of burner innards. Some had really complex diffusion constructions. Several plates, some perforated, then with short tubes through them, then more perforations. Some were so crazy I went with a large plenum volume and simple deflector that didn't restrict the flow. Introducing the flow at 90 in the plenum was a happy accident from the "why not?" department.

Frosty The Lucky.

[Mikey98118]

 

 

 

Happy accidents are my favorite form of discovery

[Frosty]

They're my favorite kinds of accident for sure, though at this stage I'm pretty happy surviving them relatively undamaged.

Frosty The Lucky.