# Steaming problems



## pickleford75 (May 3, 2012)

Need some tips on how to get more out of my alcohol fired locomotive..... seems to struggle to reach pop of pressure of 60 psi and when the throttle is opened the pressure drops rapidly..... any help or tips would be greatly appreciated... thanks in advance


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## steamtom1 (Jan 2, 2008)

Some thoughts...

Trouble making steam...
 

Water in alcohol
Wicks too tight
Loosing pressure... Steam leak somewhere​


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## cocobear1313 (Apr 27, 2012)

Has this always been the case? You may not have enough fire. Eliminate a strand or two of wick from each burner to make the fire hotter. Does it go quickly to pop off with the fan on? Could also be draft related. More detail would be helpful.


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## JEFF RUNGE (Jan 2, 2008)

Poor drafting, air leak in smoke box?


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## rbednarik (Jan 2, 2008)

For a start, this diagnostic flow chart is very helpful and can pinpoint the area(s) in need of attention. Have a look here: Flow chart

Your engine uses a JvR type B "smoke tube" boiler if I recall correctly? Regardless of that, a proper seal around the boiler shell and boiler where it enters the smokebox is crucial, as well as a tight fitting firebox to the bottom of the boiler. Any air gaps should be sealed up in either of those two places as this will destroy the vacuum that is generated by the front end. 

As others have said, the smokebox should be as air tight as possible, if you shine a high powered light from all round the outside while looking in the front you should not see any light penetration inside the smokebox. You can also test for leaks with a lazy open flame ( a candle is good) held around the joints and areas where things enter/exit with the draft fan or blower on. 

What sizes (diameter) are your blower and exhaust nozzles? Too big and the engine will not pull enough vacuum. The blower nozzle should be no more than 0.90mm (a #65 index drill) Exhaust nozzle should adhere to the rule of 1/7th the diameter of the cylinder bore to start with 

How does the fire look? It should be majority blue with very little yellow (just hints or flashes from impurities or wick material burning briefly) All yellow or orange is fuel contamination or starvation. Elevating the fuel tank slightly will determine which it is. 

Wicks should be roughly equal to the cross sectional area of the tubes. So if there are 5 off 1/2" dia flues, then the wicks should have a total area that equals that (5 off 1/2" dia wicks or 3 off 3/4" dia for an example).

Wick height against the bottom of the boiler is also crucial to good steaming. Ideally they should be no more or less than 7/8-1" from the bottom of the boiler to the tops of the wicks. 

Air intake around the burners should be about 3 times that of the wick top area. Too much is worse than too little as you are allowing large amounts of cool air to lower the temp of the fire. 

As said above, any leaks or blow by in the steam circuit/cylinders? Even a number of little leaks can add up to be parasitic over time.


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## David Leech (Dec 9, 2008)

I think that Ryan covered it all, but I would add that whilst live steam is not rocket science, it IS steam science.
I have enjoyed this hobby for the last 40 years, and have seen numerous articles written laying out the 'rules' for boiler designs in Gauge 1 over the years.
You MUST follow the rules if you want your scratch built loco to be successful.
Every time that I see someone announce on MLS that they are going to build a scratch built loco of their own design, I just hope that they at least have done the necessary research.
Ryan, you didn't mention the actual wick material, height and shape in your list above, another bit of 'steam science'.
All the best,
David Leech, Delta, Canada


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## pickleford75 (May 3, 2012)

My boiler is a 2.5 inch diameter c type with 3 1/2 inch inside diameter flues it has 4 1/2 inch diameter wick cups the wick height above the cups is about 3/8 inch... the fire burns bright blue no yellow..... with the blower i can nearly suck the fire off the wicks.... the distance from the top of the wick cups to the bottom of the boiler is about 3/4 inches... i can post pictures if this helps


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## pickleford75 (May 3, 2012)

here's some pictures of the boiler and burner installed in the locomotive hope this helps to solve my problem... again thanks for all the replies and help


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## cocobear1313 (Apr 27, 2012)

If yo pressurize the boiler (air is easiest) open the throttle and hold the wheels stationary, is there air coming out the stack? That would be leakage, probably in the valves, the description "of rapidly drops" regarding pressure leads one to believe there may be blow by past the valves or pistons or both.

Dave


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## pickleford75 (May 3, 2012)

in my air tests... the engine will run on 15 psi of air.... no, no steam escapes from the stack except on the exhaust strokes


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## rbednarik (Jan 2, 2008)

The photos help tremendously, apologies forguessing wrong on the boiler but it has been a while since viewing your build log here on MMS.

Your statement of only 3/4" from the burner pots (cans, cups, etc) points to the potential for not enough combustion room in the firebox. If the wicks are 3/8" above the cans you only have 3/8" for combustion before the fire hits the boiler bottom and hooks around in the tubes. Looking at your firebox photos there is a lot of soot buildup right near the flues which suggests poor combustion. I would bet that the unburnt fuel vapor is either catching in the flues or burning in the smokebox which would also lead to slow steam generation.

1/2" x 3 is a small flue area for this size boiler and by having 4x 1/2" wicks you are overshooting the optimal fuel-air ratio by 25%. Wick cross sectional area should be equal to the tube cross sectional area. 

Try reducing the wick power by one wick can (cap it off) and lowering the height of the wicks until the 7/8 rule is met. You may have to lower the breather in the feed sump to avoid overflowing the wicks. 

Again, for JvR A,B,and C types there must be no less than 7/8" from the tops of the wicks to the bottom of the boiler. Anything less will result in poor steaming when running on exhaust draft, blower is infinite pull of draft so that is why you can pull the fire off the wicks. 

Dave Leech brought up the one thing that was left out, what type of wick material are you using? A ceramic fiber rope (used to seal furnaces and kilns) will net you good results and is relatively easy to trim and alter until be right balance is found. Other types can be used but for ease.of eliminating the outlying variables sticking win a known working material is probably best. Try and avoid pure fiberglass as it will glaze over with use and have reduced capillary action. 

What do the wicks look like after extinguishing the flame? There should be minimal brown or black sooting which indicates poor combustion and aside from being burned in, the wicks should retain some resemblance of what they were when new.

Also when you gave a chance a few photos of the smokebox arrangement and components if you have them will be useful.


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## David Leech (Dec 9, 2008)

How long are the flues?
Now I am no expert in this matter, but I would suggest that perhaps the 1/2" diameter 'may' be too large of a diameter, and also insufficient heating surface with just the three.
You might have found that five or seven smaller diameter flues would have worked better.
However, you are not going to want to build another boiler, so try and make this one work, IF indeed it is the boiler design.
Try putting something down the flues that can conduct more heat into the boiler.
Maybe something like a twisted sheet of copper, or even bunched up nichrome wire.
This will slow the gasses and where it is touching the flue conduct more heat.
See if that helps at all, makes things better, or worse, or no change.
I think that you just need to experiment - BUT ONLY MAKE ONE CHANGE AT A TIME!
Good luck,
All the best,
David Leech, Delta, Canada


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## rbednarik (Jan 2, 2008)

So long as the flues and the wicks (fire area) are in a balanced arrangement then three each should be sufficent as it is not a large boiler. 

Ah, one more item, flue length. Should be a 20:1 ratio generally. However before throwing the boiler out as bad, altering the fire to suit the boiler will be best to settle if there are any shortcomings in the design.

Exhaust all other possibilities before blaming the boiler.


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## pickleford75 (May 3, 2012)

i misspoke earlier.... i went and remeasured i have 1.12 inches from the top of the wick cups to the bottom of the boiler the flue length is 10.75 inches long.... i'm using the ceramic wick material from the train department


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## Kovacjr (Jan 2, 2008)

Going by the Keiller formula for flues thats 126 for wetted heating area. Where 70 is average. 

You should have sufficient heating area but as Ryan stated the carbon is not good. 

The one image shows your blower line, whats attached to the end as it looked to be a good 3mm OD pipe. Drop that down to a 1mm ID nozzle. 

Also what does the stck look like and the nozzle used. Are they all calculated out and the exhaust nozzle perfectly centered on the stack? 

Does it struggle on the blower or the fan? Base of the smokebox sealed up well as is the joint of the boiler/smokebox?


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## cocobear1313 (Apr 27, 2012)

I would say it is probably not an air leak if he has a blue fire and the fire isn't falling out of the box?

dave


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## pickleford75 (May 3, 2012)

the id of the blower and exhaust nozzles are .081 inches..... it struggles on both blower and fan.... takes about 10-15 mins to reach 25 psi... i know that is very poor performace


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## rbednarik (Jan 2, 2008)

.081" (2.05mm) is ok for the exhaust, assuming 1/2"x or larger cylinder diameter it is in the ballpark although a bit on the soft side if they are 1/2". If you let us know the diameter of the cylinder bore we can give you a more accurate value.

However, it is far too big for the blower! Reduce the blower nozzle into a diameter of .035" (0.9mm, #65 index drill) or smaller. 1mm is ok if that is all which is available.

The large blower opening you have now will pull all the steam volume out of the turret when you open the blower, and it cannot supply enough to feed both that and the throttle when demanded.

That large opening will also cause a poor use of steam to draw up the fire as the wafting blower exhaust is using more than it can create and very inefficently creating a venturi at that.

As Jason said, a few photos of the smokebox arrangement when you have time will be helpful. Particularly a head on shot with the smokebox front off.


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## pickleford75 (May 3, 2012)

yes the cylinders are 1/2 by 3/4


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## pickleford75 (May 3, 2012)

here's a picture of the smoke box PLEASE excuse the crudity of the opening.... have not machined it yet


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## pickleford75 (May 3, 2012)

well i took your advice Ryan...... i reduced the blower nozzle to .035, reduced the exhaust nozzle to .073, capped the rear wick cup and made an "air dam" to block the area over the rear wick cup..... saw a lot of improvement..... i slightly spread the wicks (mushroomed) and saw a huge improvement...... now i'm noticing the the rear wick is now fluttering and turning slightly yellow when the blower is turned up... any other suggestions oh and THANK YOU VERY MUCH!!!


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## rbednarik (Jan 2, 2008)

Those nozzles are dead on, so there should be good draft up front now as you have found out. The front end is going to be the largest step in getting it from poor steaming to good. Now the last step is to get it to be a great steaming engine 


Wicks:
Looking at your wick tube height, again, you are still only at 3/4" between top of the wick material (not the physical burner top) and bottom of boiler. The fact that mushrooming the wicks increased the steaming production indicates that the fire is still choking itself from not enough combustion space.-Mushrooming lowers the fire height but also reduces the flame concentration. Ideally you want cone shaped wicks (think of a torch flame pattern) that are set at the right height to allow for the better combustion you had with the mushroomed wicks. ​You should ideally have 1.25"-1.5" between the top of the burner body and the bottom of the boiler. Keep your wicks at 3/8" high, since that is a good height. If the new space between boiler and burner top is 1.25", take out .375" for the wick height and you are left with the magic minimum of .875" (7/8") 7/8" is the target so there are two ways to go about trying this: -First you can try just physically lowering the by burner 1/8", leave the wicks alone and just pull it down to make your distance between burner top and boiler 1.25"

-Second, you can alter the burner by cutting 1/8" off of the tops of the wick tubes, and reduce the wick height by the same (actual wick height above the can stays at 3/8", you are just lowering the physical height of everything)​I would be more inclined to cap off the front wick instead of the rear one. Right now you have a large cold air intrusion space in the combustion path that will lower the heat of the fire (cold air zaps potential energy for heating the boiler) whereas capping off the front burner will not affect the combustion path temperature any. -The fluttering could also be cooling of the combustion gases from the cold air around the capped burner, but I suspect it is more the wicks are starting to burn in and swell (as they do over time), so you may need to reduce some of the material in the rear burner once all other options are exhausted. ​Blower/misc:
How high are you running the blower when you get the fluttering of the wick? If the blower is well aimed then you should not need more than a light stream coming out of the stack to make good steam. If you cannot hold your hand 6" above the stack without it being blown away, then you have too much blower on and need to dial it back. -In aligning the blower nozzle, make sure that it does not come any higher than the exhaust nozzle in the smokebox. It should be level with the exhaust nozzle and nestled in right along side of it, not obstructing the exhaust nozzle stream. You will likely have to have the blower angled so that the stream comes up the middle of the stack, or the nearest that you can get it. ​Good steaming and glad to hear it is making progress in the right direction! Keep at these last few things and let us know how you get on.


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