Suitable Boiler for a LocoMobile Twin Simple (6hp)

A special section just for steam engines and boilers, as without these you may as well fit a sail.
JonRiley56
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Suitable Boiler for a LocoMobile Twin Simple (6hp)

Post by JonRiley56 » Mon Oct 17, 2011 1:52 pm

All,

In a moment of euphoric steamboat-itis I have bought a !90 ? Locomobile steam engine. I will pick it up on Sunday. I will take it to a local machine shop to check clearances, re-bore if needed, make new bushins etc. More to come on that later.

Now that I have identified my potential engine, what size boiuler should I look for ? Bart and Fred have both mentioned the 5gph/hp ruyle of thumb. That would put me at 30gph on water consumption, or ~ 240 lbs per hour of steam.

What size water tube or fire tube boiler would generate in that range ?

I have seen several folks comment that "size matters" ahem..... ;) and that it is better to design the boiler larger than needed if possible. I was thinking that perhaps I could "over build" the boiler and be able to run a larger engine in the future, or run a nice shirt pressing operation from my garage...

thanks in advance

jon
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Re: Suitable Boiler for a LocoMobile Twin Simple (6hp)

Post by barts » Mon Oct 17, 2011 2:40 pm

Hi Jon -

Steamboats and Modern Steam Launches gives the following: 5 sq ft/hp for water tube boilers, 10 sq ft/hp for fire tube boilers. This is close to right, I think; it obviously depends on fuel, boiler cleanliness, etc.

- Bart
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Bart Smaalders http://smaalders.net/barts Lopez Island, WA
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Re: Suitable Boiler for a LocoMobile Twin Simple (6hp)

Post by JonRiley56 » Mon Oct 17, 2011 7:03 pm

Hey Bart,

Can you point me in the direction of plans a 35 to 40 sq ft water tube boiler ? I would like to set it up to burn both wood and oil like you are doing.

jon
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Re: Suitable Boiler for a LocoMobile Twin Simple (6hp)

Post by barts » Tue Oct 18, 2011 3:54 am

Can you point me in the direction of plans a 35 to 40 sq ft water tube boiler ? I would like to set it up to burn both wood and oil like you are doing.
I'm afraid I don't have plans for such. I've built one boiler, and just designed it from scratch. I'd chat with someone who's built either a Roberts or B & W style boiler; both are readily built by skilled welders. Aside from adequate strength, some interesting considerations for boiler design include:

* ample steam space... on many boilers, the water level rises significantly during periods of heavy demand as steam formation in the water increases; if you don't have enough steam space from top of glass to taking water into the dry pipe, your engine can get a slug of water (bad).

* reserve water capacity.... if the feed pump quits, you want time to get it working again, esp. w/ a wood fire since they're a lot more work to put out and harder to relight.
W/ oil, I'm happy w/ about 10 minutes; wood I'd want more.

* separate steam pipes for engine, whistle & accessories

* easy way to get all the water out of the boiler - important if you're in the freezing zones....

* water in-feed at the lowest practical point

There are lots of boiler examples in SBMSL....

= Bart
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Bart Smaalders http://smaalders.net/barts Lopez Island, WA
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Re: Suitable Boiler for a LocoMobile Twin Simple (6hp)

Post by JonRiley56 » Tue Oct 18, 2011 2:36 pm

Hi Bart,

Can you give me more detail on SBSML ? It loks like it was a magazine published for three years in the 60s. Should I try to buy all of the issues ? Are they in different volumes etc etc ?

It sounds like it would be well worth the investment.

jon
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Re: Suitable Boiler for a LocoMobile Twin Simple (6hp)

Post by DetroiTug » Tue Oct 18, 2011 3:17 pm

Jon,

Here is the book for hobby steamboating.

http://www.steamlaunch.com/books/modernbt.html

There are some used copies around, which I bought first, then after much reading fell apart. Best to buy a new one, which is what I wound up doing.

I would also add on the boiler question, being a new steamboater myself, a vertical firetube I think is a good first boiler. They hold more water and are much easier to maintain, giving the new user more time to accustom themselves with running the boat, i.e. steering, oiling, firetending, water-tending, etc.

The way boilers were explained to me when I first got in to this: The boiler is what actually creates the power, the engine is just a means to convert the boilers energy in to real work.

Ronnie at Tiny Power can get you a boiler. He sells VFT's

-Ron
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Re: Suitable Boiler for a LocoMobile Twin Simple (6hp)

Post by JonRiley56 » Tue Oct 18, 2011 8:27 pm

Hey Ron,

I ordered the book.............hopefully it will come out quickly. I have been a little scared of the fire tube set ups. Any potential explosion issues seem to be much more significant with FT versus Water Tubes. I am also hoping to keep the profile as low as possible and unless I do a horizontal FT they typically seem pretty tall.

I like the safety aspect of the water tubes. They also seem within the realm of home built if I borrow some favors from some talented welders. I assume that if I plan to run at 100 psi and run the hydro at 200 for 2 hours and it holds that it will be ok in service. I am more concened with getting the design right at this point.

I may end up going with a build from someone but I am trying to conserve $ as much as I can.

jon
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Re: Suitable Boiler for a LocoMobile Twin Simple (6hp)

Post by barts » Wed Oct 19, 2011 4:51 am

I like the safety aspect of the water tubes. They also seem within the realm of home built if I borrow some favors from some talented welders. I assume that if I plan to run at 100 psi and run the hydro at 200 for 2 hours and it holds that it will be ok in service. I am more concened with getting the design right at this point.
With a proper design, small water tube boiler construction is not difficult, but a 30 sq. ft boiler will take some time as there's a lot of pipe involved. With 1/2" nominal pipe, you'll need
4.6 feet to get a sq. foot of heating surface - so that's 30*4.6 = 140 feet of pipe, or about 120 lbs. worth. Add a drum, casing, etc. (use kaowool or Fiberfrax type insulation - not firebrick) and, even paying attention to weight you'll be prob. 300 lbs easy.

- Bart
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Re: Suitable Boiler for a LocoMobile Twin Simple (6hp)

Post by DetroiTug » Wed Oct 19, 2011 9:41 pm

Jon,

Steam is like anything else, it is safe as it is handled. Most everyone drives around with 20+ gallons of volatile fuel under vehicles, some have Propane tanks in their yards that hold 3-400 gallons of compressed LP and 250 psi working pressure, 5 gallon propane cylinders right outside our doors, almost all have water heaters with 150 psi working pressure in our homes that operate at higher pressures than some steamboats (water heaters are not constructed anywhere near as well as a power boiler) (my steamboat with a twin will operate on 40 psi, quite happily). These are safe because they are handled in a such a manner that makes them safe. Safe practice backed by codes and sound engineering is the key. Any boiler explosion on a hobby steamboat should be avoided obviously, regardless of the boiler type.

Hobby steamboaters are virtually self governed in regard to building and or operating their boilers due to state laws, and all do a commendable job at that. To my knowledge there has not been one incident of a hobby steamboat experiencing catastrophic failure of the boiler in recent (last 100) years, not from my research anyways. I've read of pipes leaking/fracturing from over-stress but no injuries were recorded in text or discussions.

Boiler explosions were common before the turn of the last century here in the US. The reasons are many, most notably, Poor material quality of steels and Iron, Poor craftsmanship, lack of codes and sound engineering for the design process and most importantly lack of training and understanding on the part of the owners and operators. It was common to allow water levels to run low dockside so the steamer could take off quickly (The steamline owners encouraged this to give the impression to those on shore that steamboat transit was very fast), then add water underway, this is where most of the explosions took place, feedwater flashboiling. That coupled with safety valves that were tampered with so they would not operate was a recipe for disaster. Hollywood has capitalized on the notion as it makes for great sensationalism in their movies. I've been asked several times about my boat "Aren't you afraid that thing is gonna blow up?" If I had any inclination that there was considerable potential for mishap, I wouldn't be running it. What I did do initially though, was educate myself by reading as much as I could and asking questions here and elsewhere. I'm still learning about it, but I understand enough of it to feel comfortable operating my boat now.

Incidentally, Laws governing Steamboat operation is the first time the US government passed laws and regulations regarding private commerce.

Here is a great paper on the subject:

http://leda.law.harvard.edu/leda/data/5 ... dacted.pdf

For someone just getting in to this and wanting to put a boat together, it may be a better move to find one already constructed as used boats do come up for sale on Ebay and elsewhere. Some of the prices they have been going for it's doubtful someone could buy all the components and construct it themselves and save any money. The old saying "The devil is in the details" definitely applies, once the hull is built or bought, boiler and engine is acquired there is still much to purchase. Piping, whistles, pumps, running gear, etc. can add up to sizable sum on it's own.

-Ron
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Re: Suitable Boiler for a LocoMobile Twin Simple (6hp)

Post by JonRiley56 » Thu Oct 20, 2011 1:38 am

Hi Ron,

point well made. I will keep my options open. If you happen across any boilers for sale I would appreciate the heads up. I am picking up the engine on sunday afternoon in Boston. I will then be amble to confirm the cylinder diameter and stroke. My assumption of 6HP is based on what I have seen published.

I am waiting on my Modern Steam boats.... book. I have a question about the HP ratings on engines. It seems it should be related to the rpms. If that is the case, how do you know what RPMs you should be turning ?

jon
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