1 Steam Cars : Phorum
General Steam Car topics
Pilot die-back
Posted by: Mike Clark (IP Logged)
Date: December 21, 2002 08:30PM
<HTML>Pilot die-back
Sometimes I see from my pilot thermometer that the pilot flame cools down when the main burner fires. This mostly happens when going over about 40mph or when standing still, but not usually when driving slower than 40. This is on an H5 with Maxwell pilot, 23 inch burner and forward facing venturis. I have seen the same when using a Stanley type pilot and other people tell me they see it on their cars too. Can anyone explain this?
My thought is that the boiler fire tubes and the upside down flue together are enough of a restriction to cause a backing up of flue gases and a slight increase in combustion chamber pressure. This pressure is driven by the air pushed in by the main burner venturis and the expansion due to the heat of the burner; if the pilot is unable to generate a similar pressure it will suffer from restricted air flow and burn cold and yellow. I fitted a pyrex glass spy window on my pilot lighting flap and sure enough can see that the pilot flame does go smoky, and in extreme instances have seen air/fuel mix being blown back out of the pilot intake. I can get the same effect on the pilot if the main burner is out by blowing air from an airline into the main venturis. A quick squirt of stack blower is enough to make the pilot flame recover. Incidentally I have a Cruban type air intake on my pilot so I don’t think the pilot flame is lifting off at speed. The effect happens with or without this shielded intake pipe.
I suppose that when stationary the flue just has no “pull”; at low speeds the movement of the car creates enough draft, but at higher speeds the extra air being pushed in just overcomes the flue draft. Having no means of measuring the combustion chamber pressure I did a few sums which show that the volume of gas at flame temperature is about four times the volume of cool air being pulled in. I also worked out that the speed of air flow to feed a stoichometric 4 gallon per hour burner through two 1.625” bore venturis is about 35mph which suggests that the extra air flow through forward motion may be quite significant.
I saw some data on forward facing air intakes on i.c. engine carburettor intakes. These people concluded that at 50mph they could get an extra 1” water gauge of pressure which wasn’t enough to give them a worthwhile power increase. In our case though, this might just be ramming in enough air to make a difference.
Has anyone actually measured combustion chamber pressure, does a really strong pilot flame avoid this problem and is there any difference between front venturi and side venturi burners?
PS I just read that G.B. Venturi 1746-1822 was the person who invented the tube and the word venturi is perfectly correct as singular but needs an “s” for plural – and I thought it was something to do with wind!
Mike</HTML>
Sometimes I see from my pilot thermometer that the pilot flame cools down when the main burner fires. This mostly happens when going over about 40mph or when standing still, but not usually when driving slower than 40. This is on an H5 with Maxwell pilot, 23 inch burner and forward facing venturis. I have seen the same when using a Stanley type pilot and other people tell me they see it on their cars too. Can anyone explain this?
My thought is that the boiler fire tubes and the upside down flue together are enough of a restriction to cause a backing up of flue gases and a slight increase in combustion chamber pressure. This pressure is driven by the air pushed in by the main burner venturis and the expansion due to the heat of the burner; if the pilot is unable to generate a similar pressure it will suffer from restricted air flow and burn cold and yellow. I fitted a pyrex glass spy window on my pilot lighting flap and sure enough can see that the pilot flame does go smoky, and in extreme instances have seen air/fuel mix being blown back out of the pilot intake. I can get the same effect on the pilot if the main burner is out by blowing air from an airline into the main venturis. A quick squirt of stack blower is enough to make the pilot flame recover. Incidentally I have a Cruban type air intake on my pilot so I don’t think the pilot flame is lifting off at speed. The effect happens with or without this shielded intake pipe.
I suppose that when stationary the flue just has no “pull”; at low speeds the movement of the car creates enough draft, but at higher speeds the extra air being pushed in just overcomes the flue draft. Having no means of measuring the combustion chamber pressure I did a few sums which show that the volume of gas at flame temperature is about four times the volume of cool air being pulled in. I also worked out that the speed of air flow to feed a stoichometric 4 gallon per hour burner through two 1.625” bore venturis is about 35mph which suggests that the extra air flow through forward motion may be quite significant.
I saw some data on forward facing air intakes on i.c. engine carburettor intakes. These people concluded that at 50mph they could get an extra 1” water gauge of pressure which wasn’t enough to give them a worthwhile power increase. In our case though, this might just be ramming in enough air to make a difference.
Has anyone actually measured combustion chamber pressure, does a really strong pilot flame avoid this problem and is there any difference between front venturi and side venturi burners?
PS I just read that G.B. Venturi 1746-1822 was the person who invented the tube and the word venturi is perfectly correct as singular but needs an “s” for plural – and I thought it was something to do with wind!
Mike</HTML>
Re: Pilot die-back
Posted by: Pat Farrell (IP Logged)
Date: December 22, 2002 01:24PM
<HTML>Dear Mike, Thank you for your findings and resulting questions. One more question is: Why do most Stanleys occasionally loose their pilot lights while coasting down long hills? It's answer should tie in with your questions.</HTML>
Re: Pilot die-back
Posted by: David K Nergaard (IP Logged)
Date: December 22, 2002 04:52PM
<HTML>The Stanley owner's manuals always say "keep a strong pilot". If the fuel pressure is high enough, the extra air from "ram effect" doesn't matter. But with only 10 psi. or so, I would expect the pilot to be very lean at speed, especially with a forward facing venturi.
I have seen several Stanleys with the front license plate on a hinge in front of the burner; flip it up to light up etc., flip it down when driving.</HTML>
I have seen several Stanleys with the front license plate on a hinge in front of the burner; flip it up to light up etc., flip it down when driving.</HTML>
Re: Pilot die-back
Posted by: Mike Clark (IP Logged)
Date: December 22, 2002 07:55PM
<HTML>Pat - pilots going out when coasting downhill - cold air must have something to do with it - maybe if the main burner is off the pilot nozzle and the whole pilot body just get cold enough to spoil vaporisation and put it out. Probably depends on how strong the flame is. I took the temperature of the inside wall of the mixing tube of my Maxwell pilot - if I fire it up outside the burner it gets up to 480 whereas when it is inside the hot burner it gets to about 750 F. It must get a lot colder when coasting.
David - I found the Maxwell works best with a minimum of 35psi but that this didn't make any difference to the die back problem. It is of course possible, probably likely, that the Maxwell which has such a minute jet (about 10thou) just does not have what is needed for a front venturi car. I'd like to know other people's experience of this. I always used a tiny shield to keep the direct airflow off the Maxwell air intake and have recently used a Cruban type air intake so I don't think airflow into the pilot is going lean, more the other way.
I tried a flap about 4 inches in front of the main venturis but took it off quite soon as it didn't seem to help the die back problem but surprisingly caused the main burner to howl much more than usual. This extra howling happened in all situations, whether standing or moving. I wouldn't even try to explain that!
Thanks for your comments.
Mik</HTML>
David - I found the Maxwell works best with a minimum of 35psi but that this didn't make any difference to the die back problem. It is of course possible, probably likely, that the Maxwell which has such a minute jet (about 10thou) just does not have what is needed for a front venturi car. I'd like to know other people's experience of this. I always used a tiny shield to keep the direct airflow off the Maxwell air intake and have recently used a Cruban type air intake so I don't think airflow into the pilot is going lean, more the other way.
I tried a flap about 4 inches in front of the main venturis but took it off quite soon as it didn't seem to help the die back problem but surprisingly caused the main burner to howl much more than usual. This extra howling happened in all situations, whether standing or moving. I wouldn't even try to explain that!
Thanks for your comments.
Mik</HTML>
Re: Pilot die-back
Posted by: Peter Heid (IP Logged)
Date: December 23, 2002 07:08PM
<HTML>Mike,
Why not Venturi, Crapper invented the flush toilet.
Peter</HTML>
Why not Venturi, Crapper invented the flush toilet.
Peter</HTML>
Re: Pilot die-back
Posted by: George Nutz (IP Logged)
Date: December 23, 2002 08:22PM
<HTML>Mike,
Good stuff. It could well be that when the burner is really going strong the positive pressure in the combustion space would "stifle" the pilot a bit. Also when the fire is off and the pilot is on more oxygen is available to the pilot, with fire on there is not much excess oxygen for the pilot around. My dim mind of tests way back show 1-2" of positive water pressure in the firebox(.036-.072psi) at full fire.
The number you gave on venturis seems correct as the velocity head(ram effect) with forward facing venturis is about 1" water pressure @ 40mph and 2" water pressure @ 60mph as calculated theoretically. Two of our SACA/NE members have taken my advice and installed/made small trumpet bells to fit into their mixing tubes with very good results, this helps reduce the 40% shock losses of air trying to ram into a flat plate to a minimum. If you want a higher burn rate with enough excess air to keep the fire clean(it also reduces burner noise for the same burn rate and allows higher fuel pressures for a higher burn rate) try some miniature trumpet shapes on your mixing tubes.
George</HTML>
Good stuff. It could well be that when the burner is really going strong the positive pressure in the combustion space would "stifle" the pilot a bit. Also when the fire is off and the pilot is on more oxygen is available to the pilot, with fire on there is not much excess oxygen for the pilot around. My dim mind of tests way back show 1-2" of positive water pressure in the firebox(.036-.072psi) at full fire.
The number you gave on venturis seems correct as the velocity head(ram effect) with forward facing venturis is about 1" water pressure @ 40mph and 2" water pressure @ 60mph as calculated theoretically. Two of our SACA/NE members have taken my advice and installed/made small trumpet bells to fit into their mixing tubes with very good results, this helps reduce the 40% shock losses of air trying to ram into a flat plate to a minimum. If you want a higher burn rate with enough excess air to keep the fire clean(it also reduces burner noise for the same burn rate and allows higher fuel pressures for a higher burn rate) try some miniature trumpet shapes on your mixing tubes.
George</HTML>
Re: Pilot die-back
Posted by: Alan Woolf (IP Logged)
Date: December 24, 2002 12:50AM
<HTML>George,
Your comments about adding a small trumpet to the mixing tubes are very interesting. Could you describe them in more detail or better yet give us a sketch of what they look like. I would very much like to try them out on my 1917 Stanley and see if that reduce the tendency of the burner to howl.
Alan</HTML>
Your comments about adding a small trumpet to the mixing tubes are very interesting. Could you describe them in more detail or better yet give us a sketch of what they look like. I would very much like to try them out on my 1917 Stanley and see if that reduce the tendency of the burner to howl.
Alan</HTML>
Re: Pilot die-back
Posted by: George Nutz (IP Logged)
Date: December 24, 2002 10:38AM
<HTML>Alan,
There just little trumpet flairs that reduce the entrance shock losses, if you have room the outer diameter should be at least twice the mixing tube diameter but not crucial. One member went to PEP BOYS and found suitable sizes in their exhaust or manifold section. Rolly Evans made beautiful ones machined out of solid brass and he has a great picture of them installed to put on the web, just where or how do I insert it??
=============================
I can help, here are 2 links:
1st links to the <a href= "http://steamgazette.com/techpage/venturis.JPG">Venturi Photo</a>
2nd links to <a href= "http://steamgazette.com/techpage/techpage.htm">Venturi Photo</a> where the photo resides.
Just use you [Back] button to return here from the links destination.
JW
Admin</HTML>
There just little trumpet flairs that reduce the entrance shock losses, if you have room the outer diameter should be at least twice the mixing tube diameter but not crucial. One member went to PEP BOYS and found suitable sizes in their exhaust or manifold section. Rolly Evans made beautiful ones machined out of solid brass and he has a great picture of them installed to put on the web, just where or how do I insert it??
=============================
I can help, here are 2 links:
1st links to the <a href= "http://steamgazette.com/techpage/venturis.JPG">Venturi Photo</a>
2nd links to <a href= "http://steamgazette.com/techpage/techpage.htm">Venturi Photo</a> where the photo resides.
Just use you [Back] button to return here from the links destination.
JW
Admin</HTML>
Re: Pilot die-back
Posted by: Pat Farrell (IP Logged)
Date: December 24, 2002 12:42PM
<HTML>Dear George, If you were to send your photo in jpeg format, to John Woodson,E-mail Address: jw@stanleysteamers.com he could post it on this Stanleysteamers web site. I am interested in these trumpets too. Years ago, out of billet aluminum, I machined what I called velocity stacks for my venturi and installed them on my '14 Stanley. It took a lot of screwing around and they looked cool when I was done. They were a larger pollished funnel, but I failed to machine your trumpet flair on them. I couldn't tell any improvement in performance so I removed them to the scrap bin. I was close. but not cigar. I would like to try again. I have a 23" Baker burner and it usually doesn't howl except when I first fire it from cold. On the road I often wish it would howl a little so that I would know if it was still burning.</HTML>
Re: Pilot die-back
Posted by: C Benson (IP Logged)
Date: December 24, 2002 12:49PM
<HTML>My recall is that the AMAL carburettor people in England had done a lot of reserch on this,,,,at least they claimed to,,,the racing carburettirs in the 40--70 vintage would be a good example, I have sold my racing stuff so I cant measure them now ,,,XXXXX As flow increases,,will the mixture stay at a good ratio,,,that is ,,not to lean or rich at max or min burn rate,,, XXXXXX This is a great subject ,,keep it going guys,,,3,, cheers, Ben</HTML>
Re: Pilot die-back
Posted by: Mike Clark (IP Logged)
Date: December 24, 2002 06:42PM
<HTML>Air intake flares. To take up Ben's comment re carburettor flares I read a summary of experiments with intake flares which suggested that a flare with a radius of 0.25 to 0.375" is best and that the outer rim of the flare should be about 1" bigger than the intake. There is no point in trying to get a funnel effect, the purpose of the flare is to help the air flow smoothly round the corner into the pipe. Without a flare the air molecules, being rather polite, spend a lot of time debating who should go first.
The Stack Venturi topic last month pointed the way to another way of shifting air in - however we have now diverted ourselves from my questions about pilot die back which I'd like to continue. I'll do another post to get back to the subject after I finish the Christmas turkey.
Thanks to everyone who has contributed - all the usual suspects - and have a good day tomorrow. I'll look for John's turkey on his webcam.
Mike</HTML>
The Stack Venturi topic last month pointed the way to another way of shifting air in - however we have now diverted ourselves from my questions about pilot die back which I'd like to continue. I'll do another post to get back to the subject after I finish the Christmas turkey.
Thanks to everyone who has contributed - all the usual suspects - and have a good day tomorrow. I'll look for John's turkey on his webcam.
Mike</HTML>
<b>Re: Rolly's venturi mod photos</b>
Posted by: JW (IP Logged)
Date: December 24, 2002 08:06PM
<HTML>This is porting and polishing for fire hackers. The principals are similar for flow thru the expander. Anytime you can improve the quality of the path for air bits, fire bits, and steam bits to follow, more bits *will* follow......[more grin]
I have posted Rolly's venturi trumpet photos, and below is shown how you can view them.
Here are 2 links:
1st link goes directly to the <a href= "http://steamgazette.com/techpage/venturis.JPG">Venturi Photo</a>
2nd link goes to <a href= "http://steamgazette.com/techpage/techpage.htm">TechPages</a> where the Venturi photos reside. This area could use some updating! Arrgh!
Use your [Back] button to return here from the links destination.
JW
Admin</HTML>
I have posted Rolly's venturi trumpet photos, and below is shown how you can view them.
Here are 2 links:
1st link goes directly to the <a href= "http://steamgazette.com/techpage/venturis.JPG">Venturi Photo</a>
2nd link goes to <a href= "http://steamgazette.com/techpage/techpage.htm">TechPages</a> where the Venturi photos reside. This area could use some updating! Arrgh!
Use your [Back] button to return here from the links destination.
JW
Admin</HTML>
Re: Rolly's venturi mod photos
Posted by: Mike Clark (IP Logged)
Date: December 29, 2002 01:45PM
<HTML>
Going back to the point of this topic which was why pilot lights sometimes die back when the main fire is on we seem to have two explanations – either the gas pressure gets high enough in the combustion chamber to stop the pilot drawing air, or as George suggested, the pilot relies partly on spare oxygen in the combustion chamber which is just not there when the main burner is going full out. Pat Farrell’s query about why pilots go out when coasting downhill may also connect with this but I can’t yet see how.
Three cures are suggested – either use the stack blower to stop pressure build up and let more air in, have a really strong pilot which can push mixture into the combustion chamber with at least as much pressure as the main burner, or improve the venturis to help more air in and keep a clean burn with oxygen to spare.
Whether reduced pilot air flow or lack of secondary oxygen to the pilot is the operating mechanism, I think poor draft in the flue is the root cause of pilot die back. There may come a point where the entraining pressure generated by the fuel jets is counteracted by pressure build up in the combustion chamber so that the rate of gas escape from the flue limits the inward air flow. If the pilot is weaker than the main burner it will go out because it can’t draw air. If it needs spare oxygen in the combustion chamber it won’t get it because the main burner is burning rich and using it all.
Continuing my maths on this I worked out that the volume of flue gases at 450 F produced by burning 4 GPH would be about 10,000 cu ft per hour which would need a linear rate of flow of about 15 ft per second into the flue which is 26 square inches cross section. At the end of the flue, at a temperature of say 180 F, the out flow would be at a linear speed of 10 feet per second. Subjectively it doesn’t seem to be anything like that so some bottling up must be happening. If you think about it this must be the case as the pressure of the main burner is the only thing making the gas flow unless the flue has draft from stack blower, steam exhaust or forward motion. Bring back Timothy Hackworth and George Stephenson!
If I am right about poor draft then a bit of stack blower should always cure the problem. It seems to on my car, although now with the winter salt on the roads I can’t get out to be sure. Has anyone else any views; also does stack blower stop the pilot from going out when coasting? That has happened to me but I didn’t try the stack blower. There are so many reasons why a pilot can go out that you really need your brain in gear all the time to understand it. That’s why we do it after all!
I read that a small jet of steam into the venturi has been tried – what does that do? I guess it is to cool the burner plate and reduce lighting back but does it do anything for the pilot? I can’t see it helping the draft.
Mike</HTML>
Going back to the point of this topic which was why pilot lights sometimes die back when the main fire is on we seem to have two explanations – either the gas pressure gets high enough in the combustion chamber to stop the pilot drawing air, or as George suggested, the pilot relies partly on spare oxygen in the combustion chamber which is just not there when the main burner is going full out. Pat Farrell’s query about why pilots go out when coasting downhill may also connect with this but I can’t yet see how.
Three cures are suggested – either use the stack blower to stop pressure build up and let more air in, have a really strong pilot which can push mixture into the combustion chamber with at least as much pressure as the main burner, or improve the venturis to help more air in and keep a clean burn with oxygen to spare.
Whether reduced pilot air flow or lack of secondary oxygen to the pilot is the operating mechanism, I think poor draft in the flue is the root cause of pilot die back. There may come a point where the entraining pressure generated by the fuel jets is counteracted by pressure build up in the combustion chamber so that the rate of gas escape from the flue limits the inward air flow. If the pilot is weaker than the main burner it will go out because it can’t draw air. If it needs spare oxygen in the combustion chamber it won’t get it because the main burner is burning rich and using it all.
Continuing my maths on this I worked out that the volume of flue gases at 450 F produced by burning 4 GPH would be about 10,000 cu ft per hour which would need a linear rate of flow of about 15 ft per second into the flue which is 26 square inches cross section. At the end of the flue, at a temperature of say 180 F, the out flow would be at a linear speed of 10 feet per second. Subjectively it doesn’t seem to be anything like that so some bottling up must be happening. If you think about it this must be the case as the pressure of the main burner is the only thing making the gas flow unless the flue has draft from stack blower, steam exhaust or forward motion. Bring back Timothy Hackworth and George Stephenson!
If I am right about poor draft then a bit of stack blower should always cure the problem. It seems to on my car, although now with the winter salt on the roads I can’t get out to be sure. Has anyone else any views; also does stack blower stop the pilot from going out when coasting? That has happened to me but I didn’t try the stack blower. There are so many reasons why a pilot can go out that you really need your brain in gear all the time to understand it. That’s why we do it after all!
I read that a small jet of steam into the venturi has been tried – what does that do? I guess it is to cool the burner plate and reduce lighting back but does it do anything for the pilot? I can’t see it helping the draft.
Mike</HTML>
Re: Rolly's venturi mod photos
Posted by: Jeff Theobald (IP Logged)
Date: December 29, 2002 07:16PM
<HTML>Hi Mike,
I have been giving some thought to your problem and I am going to throw another herring in the box, over the years I have had the pilot on the Brooks burn good and strong and very weak and wispy, but still keep going all day, now the feed water being pumped in is almost boiling after only a few miles, where as in non-condensing cars the water is almost cold, any form of leakage from the boiler will put the pilot out as soon as the main fire goes off, Could it be that when coasting down hill pumping cold water into a very hot boiler, a few of the tubes weep over the pilot where the cool water would gather going down hill and this is what causes the problem I have notice that this problem affects non-condensing cars more than condensing, Jeff.</HTML>
I have been giving some thought to your problem and I am going to throw another herring in the box, over the years I have had the pilot on the Brooks burn good and strong and very weak and wispy, but still keep going all day, now the feed water being pumped in is almost boiling after only a few miles, where as in non-condensing cars the water is almost cold, any form of leakage from the boiler will put the pilot out as soon as the main fire goes off, Could it be that when coasting down hill pumping cold water into a very hot boiler, a few of the tubes weep over the pilot where the cool water would gather going down hill and this is what causes the problem I have notice that this problem affects non-condensing cars more than condensing, Jeff.</HTML>
Re: Rolly's venturi mod photos
Posted by: Mike Clark (IP Logged)
Date: December 29, 2002 08:07PM
<HTML>Jeff,
Hope my tubes aren't leaking!!!
Don't you think the greater frequency of going out when coasting with non condensing cars is more likely due to the excess cold air at the front - maybe the cold water feed exagerates this.
Surely even after a mile of coasting with one pump going you have only added a maximum of a gallon of water which wouldn't cool it down too much.
Mike</HTML>
Hope my tubes aren't leaking!!!
Don't you think the greater frequency of going out when coasting with non condensing cars is more likely due to the excess cold air at the front - maybe the cold water feed exagerates this.
Surely even after a mile of coasting with one pump going you have only added a maximum of a gallon of water which wouldn't cool it down too much.
Mike</HTML>
Re: Pilot die-back
Posted by: Rolly Evans (IP Logged)
Date: December 30, 2002 10:33AM
<HTML>Burner light backs.
Adam I bought my 1920 in July of 2000 so I am by no means an expert on the subject. But this last year I have had no light backs.
The burner pan needs to be sealed tightly against the bottom of the boiler. All six holes the two for the super heater going in and out, and the four blow down pipes need to be packed and sealed, don’t forget to pack above the nipple on the blow down pipes between the nipple and the boiler. This whole assembly on an engineering stand point sucks.
I built a new burner pan with a matching ring. The ring is three inches deep and is held up to the boiler with four separate hangers. The burner pan mates to a flange on this ring with a sealing joint. The ring is packed and sealed to the boiler and now when I drop the burner and replace it I never have to do any packing.
The Pilot needs to be sealed where it attaches to the burner. I have a gasketed joint hear keeping it very tight. Also where the Pilot vaporizer comes through the pilot this needs to be sealed as well.
The Pilot peephole door should fit flat and snug with a good spring tension. I added a mica window to this door so I can check the pilot with out opening it. You can see this in the photo of my venturi mod.
The branch forks needs good copper washers to seal the assembly. This design also is very poor. A union joint would be better. Howard Randall’s car has a very nice attachment with a union.
The burner can cause the light back if the holes are two big. When the burner is shutting down the flame can drop through the holes and pop the remaining fumes under the grate.
This can be controlled by driving habits. Anticipate when you are going to stop and shut the main fuel off well before you need to stop. This will let the last bit fuel vapors blow away while your moving, and it lets the natural draft of the moving car keep a negative pressure above the burner. I have not found the need for a steam exhaust blower to control light back but one would is very handy to purge fumes from the burner and boiler when you have pilot problems and need to relight after dumping raw fuel in the burner and not getting ignition.
This past year my car ran very well with minor problems. The boiler is very old, a welded bottom steel tube type. Six tubes needed to be plugged.
I have started building a new modified Derr boiler. Is any one out there using Derr boilers? We have one member in SACA-NE using one with very good results.
I wish you all a very happy New Year.
Rolly</HTML>
Adam I bought my 1920 in July of 2000 so I am by no means an expert on the subject. But this last year I have had no light backs.
The burner pan needs to be sealed tightly against the bottom of the boiler. All six holes the two for the super heater going in and out, and the four blow down pipes need to be packed and sealed, don’t forget to pack above the nipple on the blow down pipes between the nipple and the boiler. This whole assembly on an engineering stand point sucks.
I built a new burner pan with a matching ring. The ring is three inches deep and is held up to the boiler with four separate hangers. The burner pan mates to a flange on this ring with a sealing joint. The ring is packed and sealed to the boiler and now when I drop the burner and replace it I never have to do any packing.
The Pilot needs to be sealed where it attaches to the burner. I have a gasketed joint hear keeping it very tight. Also where the Pilot vaporizer comes through the pilot this needs to be sealed as well.
The Pilot peephole door should fit flat and snug with a good spring tension. I added a mica window to this door so I can check the pilot with out opening it. You can see this in the photo of my venturi mod.
The branch forks needs good copper washers to seal the assembly. This design also is very poor. A union joint would be better. Howard Randall’s car has a very nice attachment with a union.
The burner can cause the light back if the holes are two big. When the burner is shutting down the flame can drop through the holes and pop the remaining fumes under the grate.
This can be controlled by driving habits. Anticipate when you are going to stop and shut the main fuel off well before you need to stop. This will let the last bit fuel vapors blow away while your moving, and it lets the natural draft of the moving car keep a negative pressure above the burner. I have not found the need for a steam exhaust blower to control light back but one would is very handy to purge fumes from the burner and boiler when you have pilot problems and need to relight after dumping raw fuel in the burner and not getting ignition.
This past year my car ran very well with minor problems. The boiler is very old, a welded bottom steel tube type. Six tubes needed to be plugged.
I have started building a new modified Derr boiler. Is any one out there using Derr boilers? We have one member in SACA-NE using one with very good results.
I wish you all a very happy New Year.
Rolly</HTML>
Re: Rolly's venturi mod photos
Posted by: Pat Farrell (IP Logged)
Date: December 30, 2002 02:57PM
<HTML>Dear Mike, While under power, the noncondenser cars' boiler's exhaust is sucked out of the top of the boiler by the engine's exhaust exiting out the flue at the back. While coasting down a hill, the non condensing car is not under power and so it looses all of it's steam exhaust vacuum. Being different, the condensing car drops it's boiler flue exhaust directly behind the boiler onto the ground, unaffected by whether the engine is exhausting steam or not. The type of exhaust exit makes the difference on which car will loose it's pilot light first on the downhill. Coasting down a long hill, the Stanley's boiler's main fire will cycle off as soon as the steam pressure regulator has reached it's steam pressure limit. Soon after the main fire has cycled off, is when the pilot light often goes out. Knowing this problem, I often approach a long downhill with low steam pressure and I only just crack on my main fuel valve just enough to maintain a main fire for the long downhill. Some times when I happen onto a down hill by chance and my main fire has already cycled off, while coasting with my non condensing Stanley, I will occasionally give my throttle a small burst of steam to maintain a draft in my exhaust flue. This too has helped keep the pilot light lit. Jeff had mentioned a water leak putting out the pilot light. I hope to never have the problem of a leaking tube doing this. The biggest problem of a leaking tube (or any steam line) is when the car is parked while under pressure, returning to the car, the boiler is found empty of it's water. It is not fun refilling an empty boiler in a parking lot. I have had the experienced having a pin hole in my superheater. Everytime that the main fire had cycled off, like leaving a stop sign and turning the throttle on, the steam leak would blow out the pilot light. On that tour, I drove 200 miles without a pilot light. We kept the fire going with using only a low fire on the main fuel valve. I have beem steaming going onto 19 years now. Happy New Year 2003</HTML>
Pat's pilot die back comments
Posted by: Mike Clark (IP Logged)
Date: January 01, 2003 03:41PM
<HTML>Pat,
Thanks for your helpful post. It’s good to hear from someone who has both condenser and non condenser cars. I know nothing of condenser cars but thought the side venturi intake must work differently to the front intake and you seem to be confirming this. My steam exhaust does go through the flue but I think from what you are saying and from my experience I need to shorten it to get more steam blast. Non condensing Stanleys probably need the steam blast to shift the extra air flow which comes with front intakes. Perhaps this was no longer needed when the side intakes were adopted so the exhaust could be moved outside the flue.
Has anyone actually measured the gas pressure in the combustion chamber – it would be a very interesting project to log this along with main fuel vaporiser pressure downstream of the steam automatic, temperature of the fire and speed of the car. Snag is the kit to do it is expensive. There are data loggers which hook into a laptop PC – then you could follow exactly what is going on. Probably nuts to do this type of development work on a 95 year old design, but fun.
Some people keep their stack blower open a bit all the time which seems steam wasteful. You could feed a restricted stack blower from a valve controlled by the pressure in the main burner vaporiser, set to come on whenever the burner fires. Don’t know if there are mechanical valves which would do this – electric would be easy but that would be cheating. Of course this wouldn’t help the draft when coasting down hill but your driving technique sounds good for that problem.
New Years greetings to all. I just did a 60 mile New years Day run in our 1925 Salmson sports car – no top and lots of rain and fog today – we’re all mad! - but happy.
Mike</HTML>
Thanks for your helpful post. It’s good to hear from someone who has both condenser and non condenser cars. I know nothing of condenser cars but thought the side venturi intake must work differently to the front intake and you seem to be confirming this. My steam exhaust does go through the flue but I think from what you are saying and from my experience I need to shorten it to get more steam blast. Non condensing Stanleys probably need the steam blast to shift the extra air flow which comes with front intakes. Perhaps this was no longer needed when the side intakes were adopted so the exhaust could be moved outside the flue.
Has anyone actually measured the gas pressure in the combustion chamber – it would be a very interesting project to log this along with main fuel vaporiser pressure downstream of the steam automatic, temperature of the fire and speed of the car. Snag is the kit to do it is expensive. There are data loggers which hook into a laptop PC – then you could follow exactly what is going on. Probably nuts to do this type of development work on a 95 year old design, but fun.
Some people keep their stack blower open a bit all the time which seems steam wasteful. You could feed a restricted stack blower from a valve controlled by the pressure in the main burner vaporiser, set to come on whenever the burner fires. Don’t know if there are mechanical valves which would do this – electric would be easy but that would be cheating. Of course this wouldn’t help the draft when coasting down hill but your driving technique sounds good for that problem.
New Years greetings to all. I just did a 60 mile New years Day run in our 1925 Salmson sports car – no top and lots of rain and fog today – we’re all mad! - but happy.
Mike</HTML>
Re: Pat's pilot die back comments
Posted by: Pat Farrell (IP Logged)
Date: January 02, 2003 05:48AM
<HTML>Dear Mike Clark, There should be no reason to shorten the exhaust stack on the condensing Stanley. It was designed to work and it did work when Stanley built it. A closer examination of your stack of "if it was faithfully reproduced to Stanley specifications" would answer the need for modifications. My 1914 Stanley feedwater heater dumps the exhausted steam inside the stack (flue) about about 4 inches from the end. This creates enough suction to easily draw the boiler exhaust out while under power. That is why when firing and while not moving, most every time, operators will raise the boiler's top lid to vent the boiler exhaust. It keeps a better fire going on inside the boiler and it will help keep your pilot lit.</HTML>
Re: Pat's pilot die back comments
Posted by: Mike Clark (IP Logged)
Date: January 02, 2003 06:35PM
<HTML>Pat,
It’s the steam pipe I’m thinking of shortening not the flue which I am sure is pretty much as per Stanley.
The steam pipe finishes about 2.5 “ into the last down bend of the flue. I have sometimes run with a rubber hose elbow on the end to get the steam right out and can’t say I found any difference in the behaviour of the burner. This makes me think the steam pipe is just too long anyway so never gives a decent draw. A bit of trial and is needed. I very much appreciate your comments and agree that the Stanley way is probably the best.
Mike</HTML>
It’s the steam pipe I’m thinking of shortening not the flue which I am sure is pretty much as per Stanley.
The steam pipe finishes about 2.5 “ into the last down bend of the flue. I have sometimes run with a rubber hose elbow on the end to get the steam right out and can’t say I found any difference in the behaviour of the burner. This makes me think the steam pipe is just too long anyway so never gives a decent draw. A bit of trial and is needed. I very much appreciate your comments and agree that the Stanley way is probably the best.
Mike</HTML>
Re: Pilot die-back
Posted by: Peter Brow (IP Logged)
Date: February 09, 2003 07:33AM
<HTML>FWIW, I noticed recently on the burner page at Ted Pritchard's website that a Stanley burner ran with much dirtier exhaust in tests than the Pritchard burner. I wonder if pilot die-back/poor pilot combustion was a factor, perhaps in all Stanley burners?
Peter</HTML>
Peter</HTML>
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