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Dec 23, 2009, 12:14 PM
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Jacques Flambeau's Avatar
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FAQ

Steam Safety


Although there are more dangerous things in this world, steam engines do have inherent risks. They use scalding steam, high pressures and things that go boom and whoosh. I've barely started thinking about steam engines, but I'm already developing a "safety mindset".

The two items I've found on the Web on model steam safety are a page from Loyalhanna and a page of safety rules from the Model Power Boat Assn:

Quote:
http://www.loyalhannadockyard.com/Saito.htm

We would like to thank Hans Spielberger for the information provided in this section as well as his expertise and technical support with all Steam Powered products.

Although powering a model boat with steam is exciting and true to life, nevertheless, one should be aware of the procedures necessary and the dangers involved.

First, some precautions: Steam firing produces considerable heat, so it is necessary to shield the hull and other structures from high temperatures. This is especially true of the smaller models, which are not well ventilated. A fiberglass hull can withstand more heat than ABS or plastic. Nevertheless, it is good to place a light metal shield around the boiler or burner. For this, you can use the aluminum sheet obtained from the disposable pans used to line ovens. The shield should not obstruct the flow of air from getting to the burner. Since heat rises, the area above the boiler and the burner should also be protected. Adequate supply of air must be provided to the burner. Cements commonly used for models is flammable even when set, it is advisable to secure the metal either mechanically or by using a substance known as “Waterglass” as a safe alternative. This is a liquid that will set and adhere to most any material. You can get it at almost any hardware store or chemical supply store.

The next precaution is to make provisions for an adequate supply of airflow to the burner and to ventilate the engine. An air starved burner will not produce sufficient heat, and the heat could build up in the hull causing deformation and discoloration. Air can be supplied by functional ventilators and gratings which would appear proto-typical, since heat and air supply were also problems in the prototype. As a last resort, a small battery driven fan could be installed in a strategic location.

Next, we must consider the dangers inherent in the fuel employed to fire the burner. At the outset, although it is commonly used in the small model stationary Steam Plants, alcohol, especially the liquid variety is not recommended. Alcohol burns with an almost invisible blue flame. Although it does not tend to explode, it burns very hot. The danger is that any spillage in the boat can be ignited without being noticed. If you then reach into the boat to make adjustments, a severe burn can result. Please be extra careful if using alcohol.

Other fuels have their own drawbacks. Any of the common gases: Propane, butane or any of the mixtures are heavier than air, and if allowed to accumulate in the boat can be set off with any spark and can produce an explosion. It is a good precaution to ventilate the hull prior to igniting a gas fired boiler. This can be done with a fan or easily by taking a folded newspaper and fanning the hull several times before igniting the burner. It is further advisable to light the burner as soon as possible after turning on the gas valve. If the burner should lose it’s flame at any time, shut off the gas valve as soon as possible. A pilot flame helps in this respect.

Now to the more pleasant part. You will find that steam firing is quiet, powerful and relatively non-polluting. There are some considerations however, that should be addressed. (Preferably at the time a decision is made to purchase a boat). First, a small boat will require a rather simple Steam Plant to fit in the limited space. Also, be aware that Steam Plants can be bulky and heavy. As noted earlier, provisions must be made for adequate ventilation. You should also consider access to the Steam Plant necessary to properly operate and maintain the boiler and engine.

STEAM POWERED UNITS IMPORTANT INFORMATION/HINTS & TIPS

On a small boat, there is usually insufficient room or freeboard to install auxiliary water tanks, therefore, the run time will be limited by the water and fuel capacity of the unit. Also be aware that the boiler must be allowed to cool and the pressure to dissipate before the boiler can be refilled. NEVER allow the boiler to run out of water while the burner is still operating. A severe explosion can result. Thus, in this type of unit, to avoid having to bring the boat to shore frequently to check on the water, it is advisable to carefully measure the quantity of fuel and water so that the fuel is expended before the water gets too low. Once the amounts are known, experiments can be conducted to determine how long this combination will power the engine. Then, simply by timing the run, the boat can be brought back while there is still fuel, water and power remaining.

When considering a larger vessel, there is a greater amount of flexibility. Here, space and weight are not generally as great a factor. When considering this type of motive power, using a type of feed water pump with an auxiliary water supply is recommended.

First, a word about the water. Considering that most models are run in some type of fresh water area, one might think that an intake to the pump leading to an opening below the water line of the hull might be acceptable. This is to be avoided. In addition to the probability of contaminants in this water, there is a real possibility that this intake could become obstructed, allowing the boiler to run dry with it’s inherent dangers. Water that has been de-mineralized is strongly recommended.

At the very least, a hand pump should be installed. This would allow refilling the boiler while it was still hot and under pressure, providing a quick turn around time. Ideally, an engine driven pump should solve the water supply problem. (Steam driven pumps are also available). Run time would then only be limited by the fuel supply.

When considering engines, size and type are dictated primarily by the size of the boat and boiler, and by the way the power is to be applied. Do not dismiss an oscillating engine. For lower pressure units, it is simple, and in the smaller sizes, very efficient.



STEAM POWERED UNITS IMPORTANT INFORMATION/HINTS & TIPS

When considering “Oilers,” the simplest is the displacement type. It has no moving parts and is reliable. It also requires little attention.

Despite the apparent complications involved in operating a Steam driven boat, there is something very rewarding in seeing your tug out on the water with steam coming from the funnel and an occasional toot coming from the whistle.

We have pointed out all the possible dangers to educate our customers in their understanding of Steam Plants and safety. However, Steam Plants are not difficult to operate, nor are they hard to install. They lend a different feeling to a model and set you apart on the lake from your fellow model enthusiasts.

If you have questions, or need further information, please contact us as we will put you in touch with Mr. Spielberger, who can help you to decide if Steam Plants are the right choice for your next boat. If you E-Mail. we can forward it to him.


HANS SPIELBERGER

LOYALHANNA DOCKYARD

[email protected]
and

Model Power Boat Association
http://www.mpba.org.uk/technical/steam_rules.htm



Do we know of any other safety references?

--Bill
Last edited by Jacques Flambeau; Dec 29, 2009 at 03:00 AM.
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Dec 23, 2009, 01:05 PM
Registered User
steamboatmodel's Avatar
Hi Bill,
A good article, but I have to disagree with "Water that has been de-mineralized is strongly recommended.". De-mineralized water should not be used it leaches the copper and bronze in the boiler. You should use distilled water.
Regards,
Gerald
Dec 23, 2009, 01:07 PM
no wings any more, just dust!
Ghost 2501's Avatar
silly question, just what is the difference?
Dec 23, 2009, 01:30 PM
Registered User
steamboatmodel's Avatar
Distilled water is water that has virtually all of its impurities removed through distillation. Distillation involves boiling the water and then condensing the steam into a clean container, leaving most if not all solid contaminants behind.
Demineralized (DM) water is another name for deionized (DI) water. It is water from which the (mineral) ions have been removed.
The Demineralized water will try to gain back the missing ions and the only place it can get them from is the boiler material. You must be very careful with brass as the zinc will leach out of it, that is why you only use copper or Bronze inside the boiler.
Regards,
Gerald.
PS The use of Demineralized water in full scale is balanced by active water treatment.
Dec 23, 2009, 01:53 PM
Grumpa Tom
Kmot's Avatar
What about filtered water? That is what I have been using. Just a Waterpik tap filter, filtering out the chlorine from the city water. Is that going to create problems in the long run?
Dec 23, 2009, 02:31 PM
Spreckels Lake, GGP, SF, CA
craig_c's Avatar
water volatilizes at 1:1200* - that makes for a VERY LARGE, VERY FORCEFUL BANG, of very hot, probably superheated steam. Never play with boilers without working, verified safety valves and blowdowns!

*Correction of error: the volume change of water after phase transition is 1700:1

Apologies
Last edited by craig_c; Dec 24, 2009 at 10:06 PM.
Dec 23, 2009, 03:35 PM
Restful User
Jacques Flambeau's Avatar
Thread OP
Quote:
Originally Posted by steamboat model
Distilled water is water that has virtually all of its impurities removed through distillation.

Demineralized (DM) water is another name for deionized (DI) water. It is water from which the (mineral) ions have been removed.
I hadn't thought of it, but that makes sense. Demin water has certain minerals (Calcium and Magnesium) that cause "hardness". It is typically made by passing tapwater through a resin ion-exchange column that exchanges Sodium ions for the Ca and Mg. As you note, the Na probably does then exchange for other metals, such as Zinc.

Memo to staff: distilled only.

Kmot, I think that the Waterpic filter is an activated carbon filter. LA gets water from the Colorado, which I would expect to be fairly mineralized.

--Bill
Dec 23, 2009, 03:37 PM
Damp and Dizzy member
Brooks's Avatar
The distilled vs de-ionized water debate rages on all fronts, I've never visited a steam board without one :-).There is no difference, chemically, between the two. Do a search and listen to chemists, like I did, and convince yourself if you want. Or just use distilled, it's cheap at the grocery store.

The de-zincification problem exists...sort of. Some boiler fittings crumble after years of storage in water, some don't. It depends on the metal mix, apparently. Lots on the web, if you are interested. Mostly, the model live steamer "deionized kills" rumor/process/truth/whatever arose after a steamup in Britain lead to boiler problems in a bunch of participants. The de-ionized water supplied by the organizers was blamed, but reading the symptoms, I think it was more likely they just got some bad water, sold, possibly, as deionized, but, in actuality, not...

Metal soluability considerations suggest that water left in the boiler at the conclusion of steaming secession should reach an equilbrium with ion exchange. If true, and I have no reason to doubt it, that suggests that draining your boiler after a session (common suggestion to avoid dezincification) will Hasten de-zincification. If you are worried, toss a chunk of pure Zn into the boiler and use it as a sacrificial annode.

I've never had a problem using distilled water, leaving it in the boiler, is all I can say. I use distilled cause it's cheap at the supermarket.

Yes, Kmot, using tap water will give you problems. The waterpik does not remove all the calcium (Ca), which will lead to Ca gunk buildup over time. It's the same process as you see in your teakettle or coffee machine. Soft water ditto. Some Brits use rainwater - with all the airpollution, there is no especial cleanliness of rainwater (but it might not be as hard (containing lots of Ca ions) as the local tapwater). Best, for longevity of your system, is distilled Or deionized.
Last edited by Brooks; Dec 23, 2009 at 03:43 PM.
Dec 23, 2009, 03:50 PM
Damp and Dizzy member
Brooks's Avatar
Regarding "severe explosion" if a model boiler is boiled dry - Hogwash for model sizes. Proven by a series of tests by an Australian modeling group. They tested to destruction several boilers, some made with best practices and some slopped together. In no case could they get an explosion. The worst that happened is that a seam let loose - bad if you are in the path of hot, steamy water, but no shrapnel.

Everyone has "heard of a friend of a friend" who blew up. The only authentic situation that I know of was a ride behind steam tractor model, much bigger than the boats we float. *Size matters* - the explosive potential of water flashing to steam is real enough, but the Quantity of water available controls the energy available to do damage. And model boilers simply don't hold enough energy.

This Debate will rage on. Convince yourself one way or the other :-).
Dec 23, 2009, 05:27 PM
Grumpa Tom
Kmot's Avatar
Switching to distilled. Thanks!
Dec 23, 2009, 05:57 PM
Registered User
steamboatmodel's Avatar
I know I recommended distilled water, but I have used filtered pond water and tap water. Both have worked in the boilers, I just had to clean out the boiler more frequently, the same way I clean out the coffee maker and kettle. As for the Demineralized water(de-ionized) / distilled water debate, I have listened to chemists and no two agreed. This is a big subject not just for models but for full size boilers. I worked for many years as a building operator running up to six large boilers, and I would not want to have to treat my model boilers the same way we had to run the big ones. Every Chemical salesman would insist that you were treating your boilers wrong. I decided that with my models I would use distilled when I could, and decalcify when useing tap water.
Regards,
Gerald.
Dec 23, 2009, 06:08 PM
no wings any more, just dust!
Ghost 2501's Avatar
Quote:
Originally Posted by steamboatmodel
...Every Chemical salesman would insist that you were treating your boilers wrong....
they would, they want to sell you their product
Dec 23, 2009, 08:26 PM
Registered User
steveciambrone's Avatar
(NEVER allow the boiler to run out of water while the burner is still operating. A severe explosion can result.)

The above statement is incorrect, when model boilers run dry no more steam can be produced and the pressure drops to Zero. I know this because I have done it several times. The only caution is to imidiately turn off the gas and let the boiler cool then you can refill the boiler and run again.
The trouble with RC boats is the boiler can run out of water in the middle of the pond and the burner will continue to burn. In this case when retreived the boiler should be inspected by an experianced steam modeler or manufacturer. It may have to be repaired or replaced.

This safety thread can be a source of painful debate sometimes by some who have no first hand experiance with the subject. Considering the first post has errors I recommend this sticky thread be deleted. Good intentions but a real can of worms.

Thanks
Steve
Dec 23, 2009, 09:45 PM
Registered User
steveciambrone's Avatar
Quote:
Originally Posted by craig_c
water volatilizes at 1:1200 - that makes for a VERY LARGE, VERY FORCEFUL BANG, of very hot, probably superheated steam. Never play with boilers without working, verified safety valves and blowdowns!
This is an alarmest type of statement which is not applicable to model boilers even flash steam. Most model steamers can run quite well at 40psi or less and are very safe. Safety valves are a important part of every steam boiler but many steam boilers do not have blowdown valves and do not have a need for them.

Steve
Dec 24, 2009, 12:05 AM
Registered User
lazer155's Avatar
I agree, some of the cheddar steam plants can run at 70 psi.


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