Time for a propane thread!!

Hi all:

Someone has to take this pony by the tail!! It's time to establish a thread about the use of propane for firing steam boilers.

My personal concern is that we may lose the potential advantages of propane firing--and (in my situation) in particular for small-scale projects such as steam bikes, karts--or maybe motorcycles at the upper end of the scale.

The potential complications of firing small steam power systems with anything other than propane is IMO a probable death knell for those who might otherwise be interested.

I would like to propose that a set of simple rules/parameters should be established in writing for any propane-fired steam project which would then be in accordance with written SACA parameters.

My concern is that this effort might become something beyond reason in terms of meeting written requirements. OTOH if we can remain within reasonable operating parameters we can also provide increases in safe operation too.

I'll be interested in all inputs--and expecting a huge furball. However, this issue needs to be addressed and all participants are invited. Personally, I remain an advocate of propane for "small" projects such as my kart effort; if done properly they can minimize the potentially deadly effects of improper or careless attempts and provide guidance instead to those potential participants.

Let the fun begin!!

BH

Bill, I support you. As long as there is no chance that the gas can collect and be ignited. Completely open like like a go kart.

By the way vaporizing burners can lead to explosions as well. My grandparents kitchen stove blew up. It had a vaporizing burners similar to a Stanley. or Coal-man camp stove. The oven went out and my grand father was relighting it. He was lucky slight burns and blown into the dining room. Blew the kitchen windows out and the top of the stove off.

steamerandy Wrote:
-------------------------------------------------------
> Bill, I support you. As long as there is no chance
> that the gas can collect and be ignited.
> Completely open like like a go kart.
>
> By the way vaporizing burners can lead to
> explosions as well. My grandparents kitchen stove
> blew up. It had a vaporizing burners similar to a
> Stanley. or Coal-man camp stove. The oven went
> out and my grand father was relighting it. He was
> lucky slight burns and blown into the dining room.
> Blew the kitchen windows out and the top of the
> stove off.

Thanks Andy!

I'm hoping for positive and contributory replies to this thread. Your reply is a great, first sign.

BH

It is not that the odorant in "propane" (technically Liquefied Petroleum gas, a mixture of mostly propane and butane) disperses faster than the gas but the human olfactory sense slowly becomes less sensitive to strong odors with exposure time. You will eventually be able to smell other faint odors in the presence of LP gas odorant, even if the LP gas does not dissipate. Also, there is wide variation in olfactory sensitivity from one person to another.

I heated my home with LP gas for many years. I have used LP gas in industry. LP gas is safe and reliable when used sensibly.

Heating an LP gas tank above nominal ambient temperature to get increased gas production or inverting or laying an LP gas tank on its side to get liquid will lead to disaster. If the gas tank is not producing gas fast enough with the normal orientation, the tank is too small.

Only approved valves, pressure regulators and fittings should be used. A properly designed LP gas system will include a pilot light with thermocouple and safety shut off valve or an electronic igniter with a UV light or ionization flame detector and safety shut off valve.

Consumers should never attempt to refill small tanks from larger ones. Overfilling a tank (modern refillable tanks have float valves to stop filling at the appropriate level) or refilling small tanks not meant to be refilled may result insufficient head space above the liquid. The pressure can rise abruptly with a slight increase in temperature causing the pressure relief valve to open. Assuming the relief valve is large enough to vent gas faster than it is produced, the tank itself will not burst but the result may well be a flammable or explosive atmosphere.

All pressure vessels should be regularly inspected and hydro tested, regardless of the fluid contained. All pressure vessels should have properly engineered pressure relief valves. It is not difficult to calculate the maximum possible rate of pressure rise in a system. It is not expensive to fit a pressure system with an approved pressure relief valve.

I would love to have a Stanley or other antique steam car, but the pilot and fuel tanks pressurized with air make me shudder. How many of these have proper pressure relief valves? How many of these are tested frequently? How many are replaced before they fail? In fact, it seems to me that a careless Stanley operator could have both starting (gasoline) and main (kerosene) valves open at the same time and connect the higher pressure main fuel system to the lower pressure pilot tank with bad results.

I used to enjoy amateur sports car and motorcycle racing. Strict technical inspections are required. If you don’t want to or cannot afford to play safely, you are not welcome.

It seems unreasonable for any steam club to outlaw LP gas per se. Given the litigious nature of our society, it is foolish for any steam club to permit the use of any high density fuel source without approved safety appliances and practices.

Kerry

I believe that propane is used as the entire fuel source for vehicles, regularly - inside enclosed buildings, no less. In forklifts.

Liquid and gaseous fuels will quickly maim you and quickly kill you. Millions of people, of a wide variety of intelligence levels and mechanical abilities, use liquid and gaseous fuels constantly without ever being maimed or killed.

Banning the entire population's beneficial and correctly-managed use of a fuel, based on the errors of a few, feels like overkill. However, let us suppose that there were some identifiable group of individuals who were more than usually prone to dangerous errors in fuel handling. If that were true, it might seem more reasonable for those who control the activities of that group to enact limits on the behavior of everyone in the group.

Great comments guys! This is the kind of "hands-on" experience I would like to see here and now.

I'm hoping that after a few days of posts we can start thinking about a set of realistic parameters for all to agree upon and to adhere to. Right now it's a great time to air-out your experiences and even your feelings--but ultimately we need to be able to establish some kind of operating parameters that can be written down and used for "rules" that will have to be adhered to.

Keep 'em coming, it's your time to comment here.

BH

Kerry posted:"...I would love to have a Stanley or other antique steam car, but the pilot and fuel tanks pressurized with air make me shudder. How many of these have proper pressure relief valves? How many of these are tested frequently? How many are replaced before they fail? In fact, it seems to me that a careless Stanley operator could have both starting (gasoline) and main (kerosene) valves open at the same time and connect the higher pressure main fuel system to the lower pressure pilot tank with bad results."
Rebuttal on the Stanley: The two gallon Stanley pilot tank is pressurized to 15 pounds. There is a ball check to prevent the main fuel from backing into the lower pressured pilot fuel tank. The main fuel pressure retaining tanks contain about two or so quarts of fuel back up with an equal volume of air to provide a constant main fuel pressure. All modern vehicles have fuel pumps located in their fuel tanks that provide a pressurized fuel line the full length of the vehicle and having an electrical fuel pump, unlike a Stanley, fuel will flow whether the engine is running or not. When is the last time that your modern fuel system has been regularly tested? Every time that a Stanley operator fires up his Stanley, he is hand pumping his fuel and is checking for leaks. No leaking fuel is allowed on a steam car. Unlike propane, Stanley's leaking fuels are visable. Same as a modern car, there is a fuel bypass valve on the main fuel system of the Stanley to limit the main fuel pressure to the normal operating fuel pressure. All of them have the fuel pressure relief valves. This propane thread is getting off topic, we are supposed to be discussing the merits and safety of propane. As far as I know, propane fuel vehicles is allowed by SACA, Inc. The HCCA,Inc does not allow propane fired vehicles to attend their functions. I do not believe that propane fired boilers belong in a boat.



Edited 1 time(s). Last edit at 02/12/2014 11:56AM by SSsssteamer.

Fellas,

Please know that I'm not trying to prove anyone wrong or contradicting any points for the sake of it. Just attempting to throw out some important considerations and facts about Propane. If one is storing it near an open fire and are comfortable with the risks involved, by all means proceed. I personally opt not to do so. The NPGA has already written guidelines for safe handling. As far as hands on experience, I've handled and transfered literally millions of gallons of Propane.

Someone mentioned that Butane and Propane are mixed together. That is highly unlikely. Propane and Butane are two very different liquids/gases. Propane boils at -44°F and Butane boils at +30°F. Butane is a hotter gas consisting of four carbon atoms per molecule - C4H10, whereas Propane consists of three carbon atoms per molecule - C3H8. Mixing the two together would change the boiling temperature and effect the vaporization rate for which the respective system was engineered - as well as the BTU output. Propane is one of the most expandable and contractable liquids that exists, comparing it to other liquid fuels like gasoline and kerosene is an apples an oranges example. That is why it is sold by weight at the retail level and tanks are sized by WC or water capacity volume. To determine a tank size, take the WC# value and divide it by 8.35 and the multiply it by 4.24 than multiply by 80 - that is how many pounds of propane it is designed for.

It is sold volumetrically in the Motor fuel and home heating applications. To ensure accurate delivery of product the meters are temperature compensated and they are certified and checked by the state they operate in on a regular basis. Large storage tanks are measured by a rotating spit valve mounted in the tank end, the percent reading is calculated against the water capacity of the tank and then a "correction factor chart" is used to determine how many gallons are present. The higher vaporization temperature or boiling point of Butane pretty much killed it for home heating applications, anything below 30°F there is zero pressure. (Note the parallels with steam boilers) It is a very low pressure gas at ambient temperature and why it is and can be used in plastic cigarette lighters etc. The only way Butane can be used for home heating etc. is to bury the tank and use the ground heat for vaporization. Both need heat to vaporize and make gas. They will pull the heat from anything to so (why tanks form ice when the vaporization rate is exceeded). Propane also makes an excellent refirgerant due to this characteristic and from what I understand is used as such in some very specialized applications.

Regarding motor fuel applications referenced above: All of the components of a motor fuel application are much different than those used in common grill and camp stove applications which are desinged to handle pressure in the 14 inches of water column range, or about 1/2 psi. The tank is built much stronger and the piping and hoses up to the vaporizer which are stainless steel braided are capable of handling much higher pressure than the tank itself, over 250 psi. Also every fitting on the tank is equipped with an excess flow check (unlike grill bottles), if any of the piping were to rupture, the excess flow check immediately halts the flow. Portable tanks that I know are not equipped with any such device.

In the chart below, pressure by temperature is clearly displayed. Note that this chart indicates 312 psi for a relief valve release. We were trained that all are set at 250 psi and that is true for on site tank installations. It can clearly be seen from the chart that above 120 degrees, the tank is in very close proximity to automatically releasing gas. If that happens and there is a source of ignition in close proximity, it is going to result in an igntion of the gas.



Be careful, Ron



Edited 2 time(s). Last edit at 02/12/2014 11:01AM by IronChief.

IronChief Wrote:
-------------------------------------------------------
> Fellas,
>
> Please know that I'm not trying to prove anyone
> wrong or contradicting any points for the sake of
> it. Just attempting to throw out some important
> considerations and facts about Propane. If one is
> storing it near an open fire and are comfortable
> with the risks involved, by all means proceed. I
> personally opt not to do so. The NPGA has already
> written guidelines for safe handling. As far as
> hands on experience, I've handled and transfered
> literally millions of gallons of Propane.
>
Thanks so much for your input. You are just the kind of person we need to provide the expertise necessary for this issue.

I think there's so much BS on this subject (and I'm as guilty as the rest). It looks like the use of propane may be quite important and I hope you will continue to provide input as required.

I would also like to see some POSITIVE input on this issue; this would include potential safety requirements that would minimize the potential for disastrous events. C'mon guys--it's time for results here!

BH

Ken

I disagree with your statement: “This propane thread is getting off topic, we are supposed to be discussing the merits and safety of propane.” My opinion is that LP gas is safe and reliable if used sensibly. Sensible use of LP gas requires approved practices and appliances.

The fuel pump in a modern car has a relay that permits the fuel pump to run for a couple of seconds when switching on, and then for a couple of seconds after the last ignition pulse. If the engine stops running, the fuel pump stops very shortly after. It has been a long time since cars had electric fuel pumps that ran whenever the ignition switch was on.

I used to enjoy old cars, too (mostly European sports cars). I was always careful to see that cars which had electric fuel pumps were retrofitted with a modern ignition pulse sensing relay to control the electric fuel pump. There are other methods of accomplishing this safety requirement, but the pulse relay is cheap and easy to retrofit. The fact that it was not a legal necessity did not matter to me. I did not want to burn to death in the event of a collision.

The fuel systems in my modern cars are checked for leakage every year. Leakage is not what I was talking about.

I said: “All pressure vessels should be regularly inspected and hydro tested, regardless of the fluid contained.” When a piece of tubing is over pressured, it just splits. Both ends are still attached. The fluid gets out, but because the hoop stress is very low with small diameter tubing, and because the flow impedance of the small tubing, there is no danger from flying pieces.

If a pressure vessel is filled with gas, or volatile liquid above its boiling temperature at atmospheric pressure you have a lot of stored energy. When such a pressure vessel bursts you have bits of sharp metal flying around at high velocity. This is in addition to the rapidly expanding cloud of whatever was in the vessel.

The fuel pressure regulator in your Stanley (or for that matter, the fuel pressure regulator in my modern car) is an automatic control valve. Safety pressure relief valves are not used for control purposes. They are used only to protect when the control devices and operator attention fail.

The air compressor in my garage has a safety pressure relief valve. Its only function is to vent pressure from the air tank faster than the compressor can make it up if the pressure control switch fails. I test the pressure relief valve on my compressor every couple of years.

I remove the pipe fittings and inspect the inside of my air tank every few years. I replace the tank when I see signs of internal corrosion- tanks are not that expensive. In fact, I spend a little more to get a “board certified” tank. I hydro test the tank every few years, too. It is not expensive or difficult. This is not required by law, but I have seen the aftermath of a couple of pressure vessel failures.

I did not know about the ball check in the Stanley pilot fuel line. This is a good thing to have. I have heard of Stanley pilot fuel tanks corroding internally.

I have heard of Stanley main fuel pressure tanks splitting at the seam and rapidly discharging their contents. Stanley main fuel pressure tanks are available on the aftermarket. Someone must have reason to replace them.

I am sorry I disturbed your peace by implying that your old Stanley is not up to modern safety standards, but I stand behind my remarks. The pressurized fuel tanks in your car make me shudder. Your unwillingness to inspect and install pressure relief valves on your pressure vessels frightens me.

Many things are not illegal only because the public does not know the risks. Then we have an accident that draws the public’s attention. Our unwillingness to address safety issues proactively will eventually cause the public and government to address them for us.

Kerry

Ron

I operated, maintained and managed natural gas and LNG plants for fifteen years. I am well posted on this issue.

Hydrocarbons are quite soluble in each other. Gasoline, for example, is a complex mixture of many hydrocarbons with different boiling points.

Carbon dioxide goes directly from solid to gas at atmospheric pressure and -109F. Carbon dioxide boils at 70 psig and -70F. Yet you can dissolve a lot of CO2 in water.

Butane and propane come out of the ground together; they are liquefied together and go into the distillation column together. The column is tall and cylindrical with many trays. The highest boiling temperature components tend to be found in the bottom of the column (reboiler) where heat is applied. The lower boiling temperature components tend to be found at the top of the column (condenser) where cooling is applied. The high boiling components bubble up through the liquid on the trays until they find a temperature where they condense. The low boiling components overflow weirs on the trays through down comers to lower level (higher temperature) trays. You can withdraw product from the condenser, reboiler or trays according to the mixture you want.

Yes, propane is an excellent refrigerant. Better still is a mixture of propane and butane or other hydrocarbons. By using a mixed refrigerant you can tailor the properties of the refrigerant to optimize the refrigeration process at the exact temperature you need. Many LNG plants use mixed refrigerant cycles.

Boiling can be a confusing way to think about these things. Boiling temperature implies knowledge of vapor pressure above the liquid. Water boils at 212F at standard atmospheric pressure but water will evaporate from a glass sitting on the table. While the liquid water is evaporating, water vapor molecules from the air are condensing. What we are really concerned with is the temperature at which a sufficient quantity of liquid evaporates in excess of the vapor that is condensing.

You are quite right about the pressure in a LP gas tank rising with temperature. Most household consumers are not aware of this as long as they get enough gas out of the tank to heat the house in the winter. For this reason, most LP gas heaters and engines operate at low pressure.

LP gas tanks are always painted a reflective color. Small LP gas tanks and for that matter compressed gas cylinders are supposed to be provided with a sun shade.

Kerry

For thirty years, I have kept our Stanleys is excellent condition and I test all systems every time before road use. I hydro test their boiler annually and I test all safety valves at the same time. Every pressurized system on a Stanley has a pressure safety valve built in by the Stanley steam car company and I maintain them. As an added precaution, I carry two fire extinguishers and I tell my passengers what valves to turn off in case of any questionable behavior of the car if I am not in attendance at that moment.
An interesting article about the odor of propane becoming non detectable while propane is still present follows:

Odor fade can occur when there is an underground propane leak. The movement of gas through the soil can filter out the odorant.

Oxidation (a chemical reaction involving internal rust in the tank or cylinder) also causes odor fade. New and reconditioned tanks and cylinders that sit too long before being filled are prone to internal rust when moisture and air get inside.

Adsorption is another cause of odor fade. The odorant in leaking gas can adsorb (stick) on new or old building materials such as unpainted or untreated masonry, rough wall surfaces and on furniture fabrics and drapes, thus reducing the intensity of the odor. Adsorption of odorant can also occur on the inside walls of gas piping and static or periodically used propane storage containers and distribution systems.
Information found at: [www.easternpropane.com]

Kerry posted: "Given the litigious nature of our society, it is foolish for any steam club to permit the use of any high density fuel source without approved safety appliances and practices."

Apart from my natural tendency to dislike steam club edicts (refer to the fallout from attempts of other clubs to do so), Kerry's statement points to an attitude I could get behind.

1. If you don't install and manage your pressurized kerosene or gasoline properly, we don't want you in our activity.
2. If you don't install and manage your pressurized liquid pilot fuel properly, we don't want you in our activity.
3. If you don't install and manage your pressurized gaseous fuel properly, we don't want you in our activity.

etc.

Kerry,

The company I worked for had a very comprehensive training program consisting of weekly safety meetings and week long "schools" that were mandatory regarding the Propane we were handling. At no time was there mention of mixing Butane with Propane, not saying that it isn't, we simply weren't taught that. And the way they wound on about each topic ad nauseum, it seems it would have came up, but never did. The reason I said it was highly unlikely, first as mentioned, it was not part of our curriculum and secondly, the expansion rates by temperature with each liquid is different. This would make temperature compensation performed within the meters to measure inaccurately. Also, 33,000 gallon railcars would not calculate properly. I don't doubt that's happening though, I have seen many things that were done that short-changed the customer (not my decisions)..i.e. Unmetered vapor return to bulk delivery vehicles supposedly to make the tanks safer to fill or some nonsense, many gallons were taken from the customer in vapor form in that manner. One day they came through and pulled all of the vapor return hoses, they never told us why, rumor was the company was sued over it through one of their branches by a commercial customer.

Anyways, that was many moons ago and I'm out of it for good.

-Ron

Kelly Wrote:
-------------------------------------------------------
> Kerry posted: "Given the litigious nature of our
> society, it is foolish for any steam club to
> permit the use of any high density fuel source
> without approved safety appliances and
> practices."
>
> Apart from my natural tendency to dislike steam
> club edicts (refer to the fallout from attempts of
> other clubs to do so), Kerry's statement points to
> an attitude I could get behind.
>
> 1. If you don't install and manage your
> pressurized kerosene or gasoline properly, we
> don't want you in our activity.
> 2. If you don't install and manage your
> pressurized liquid pilot fuel properly, we don't
> want you in our activity.
> 3. If you don't install and manage your
> pressurized gaseous fuel properly, we don't want
> you in our activity.
>
> etc.


Kelly... Well said. SSsssteamer

1. If you don't install and manage your pressurized kerosene or gasoline properly, we don't want you in our activity.
2. If you don't install and manage your pressurized liquid pilot fuel properly, we don't want you in our activity.
3. If you don't install and manage your pressurized gaseous fuel properly, we don't want you in our activity.

> Kelly... Well said. SSsssteamer

Kelly has brought up a most valid point that cannot be ignored. Many thanks.
Let's go one step further and request our Board take up this question at their next meeting.
If a Safety Chairman is elected to the Board, let's be sure he knows his subject very well.
Actually, after the Nutting disaster didn't SACA make such safety requirements part of our charter?
Jim

Hi Jim,

There may have been some rules regarding safety laid down for meets, but I haven't seen any such rules promulgated in the charter. I wouldn't think the rules would be too difficult or onerous....most mass produced vehicles today have fuel tanks underneath the vehicle and any leak, be it liquid or vapor, drops out of the vehicle and disperses on the ground. In situations where a concentration could potentially build up, it might be advisable to require some sort of fan to evacuate vapors from the compartment; many boats with inboards have bilge blowers with explosion proof motors to vent fumes....although avoiding the issue by situating the tank in the open seems far more secure. Under no circumstances should fuel ever be allowed to be stored in the pasenger compartment or any part of the vehicle with free and direct communication with passenger compartment. Add in a few other details such as requiring appropriate relief valving that also vents to a safe zone and you probably have all that you need.

Regards,

Ken

frustrated Wrote:

> There may have been some rules regarding safety
> laid down for meets, but I haven't seen any such
> rules promulgated in the charter. I wouldn't
> think the rules would be too difficult or
> onerous....most mass produced vehicles today have
> fuel tanks underneath the vehicle and any leak, be
> it liquid or vapor, drops out of the vehicle and
> disperses on the ground. In situations where a
> concentration could potentially build up, it might
> be advisable to require some sort of fan to
> evacuate vapors from the compartment; many boats
> with inboards have bilge blowers with explosion
> proof motors to vent fumes....although avoiding
> the issue by situating the tank in the open seems
> far more secure. Under no circumstances should
> fuel ever be allowed to be stored in the pasenger
> compartment or any part of the vehicle with free
> and direct communication with passenger
> compartment. Add in a few other details such as
> requiring appropriate relief valving that also
> vents to a safe zone and you probably have all
> that you need.

Ken:

Thanks for your "reality check" here. I was never proposing using propane for anything other than the smallest steam projects which would include bicycles, karts, and motorcycles. Each of these has essentially totally open systems and there would seem to be no possibility of gaseous accumulations as a result.

In addition, another detail which I've incorporated in my project is the use of a pressure regulator directly attached to the propane tank. This means there is only one high-pressure connection to the "real-world" and that should be monitored diligently IMO to verify a leak-free connection. I'm currently regulated down to a pressure of 20 psig which is substantially below any potential pressure the tank is capable of. OTOH it doesn't even begin to get down to the nearly "breathless" values used for household apps. All worth keeping in perspective here.

Also (and noted by several SACA folks--thank you!) there have been a significant handful of participants at the Berrien Springs meets over the last several years, all of whom have been using propane firing (and even butane!). The perceptions of safety issues seems to have been minimized--in spite of the fact that Bill Ryan has indeed needed his backside fire doused on several occasions.

Perspective is required here, just my opinion.

BH



Edited 1 time(s). Last edit at 02/14/2014 09:53PM by Bill Hinote.

is there a way to route the propane from pressure valve to the combustion chamber, where it would burn harmlessly away?

Dumping excess propane into the burner might lead to an excessively rich mixture and extinguish the burner. Likewise, if routed through an ejector nozzle to induce adequate air, you might get a destructive burst of heat into the boiler as you have now essentially bypassed your normal control methods.

Ken

[en.wikipedia.org]

Domestic and commercial "propane" is a mixture normally. That is why in many markets it is refered to as LPG (Liquified Petroleum Gas)
Alternatively type in Domestic Propane MSDS (Material safety data sheet) a lot of examples will come up showing a particular companies blend of the day

One example there are many others
[www.superiorpropane.com]

Cheers
Mark

The time Bill Ryan caught on fire (when I was there) was due to oil from the drive chain being thrown on the back of the seat, his close maybe and ignited by the firing heat from the boiler. Fuel had nothing to do with the fire that time. I know I was there. Chased him down smothered the fire out on him. Someone showed up with a fire extinguisher and got the fire on the kart out. It was not an explosive fire. But had the oil been on bare skin he would have had some vary bad burns. We had two mishaps that year that could have been a lot worse. The Green Monster throttle stuck wide open.

One of the problems I have to say is that things are not being reported to the organizers. If one sees a potential problem it should be taken up with the organizers of the event. If the gas smell had been brought to the Knots organizers attention the Nutting incident might not of occurred. I know it's easier to ignore problems and it may cause trouble with friends. But I would put lives ahead of everything else. Hind site is always better.

Andy



Edited 1 time(s). Last edit at 02/19/2014 02:37AM by steamerandy.

Propane by composition 90 - 99 % Propane and 0 - 2.5% Butane is not enough to be considered a "mixture" of the two liquids. According to this MSDS, Propane may or may not have a very small amount of Butane present averaging in the one percentile range to zero in winter months when it is predominantly produced and handled.

Also, this MSDS indeed refers to -42F as the "boiling point".

The most important consideration in the safe handling of Propane is not the pressure, but the understanding of how temperature determines the volume of the liquid. In cold climate winter months, it's possible to put over 500 gallons in a 500 gallon tank and still be under 90% volume. This is a most dangerous situation because if for some reason the LP is not used it will be released when the ambient temperature rises. Again that is why it is sold by weight and not volume at the portable retail level, it makes it less likely to overfill a cylinder. In the chart above, the curve in the graph is clearly displayed an exponential rise in pressure by temperature as it increases.This is the result of the expanding liquid.

I'm in the process of piecing a steam vehicle together and am opting to forgo the propane option. The way I figure it there is already a potential of being burned, scalded and exploded. Do I really need to add any other potential safety concern?

As I stated in an earlier post if one is using it and comfortable with the risks involved, proceed. My posts are merely to inform and help folks understand the gas they are using a bit better and the risks involved. If a tank pops off and there is a source of ignition it is going to be an instant fire, don't bother grabbing a fire extinguisher, it's not going to put it out and it will be over by that time. Hopefully, without injury to anyone. Also, if there is an uncontrollable leak and there is a fire, let it burn. It's better to do that than to allow a large vapor cloud to form which can cause a much larger explosion. In a sense, fire is one way to control the situation. That is how we got rid of gas sometimes. Many old underground butane tanks buried in the 50's are still around - and have gas in them and some people smartly want them out of the ground. Most of those did not have a liquid port, so the gas would have to be burned off in vapor form. Made for a long boring day, watching a 40' tower of flame. Some of them we burned off and removed had gas in them 30 years old and it still burned perfectly. It was too dangerous to try to dig the tank up with gas in it, not knowing the level of corrosion to the shell.

Here is a good example:

[www.youtube.com]

I'm not sure, but it looks like this bloke got out with a cigtarette in his mouth smh.. He got out of the mood of trying to do something about it in a hurry. Looks like a leak in a motor fuel line and not enough for the excess flow check to shut. The large surges in the fire are from the tank popping off due to the temperature, the explosion at the end is when the relief valve was no longer capable of discharging the gas.

-Ron



Edited 1 time(s). Last edit at 02/19/2014 08:08AM by IronChief.

I run a propane fired steamboat, and that operation can be conducted in a safe manner with prudent safety precautions. Propane has an inherent problem in that it is a gas that is heavier than AIr, and if there are leaks it will accumulate in low places.

That being said, propane fired equipment is fitted to many thousands of houses with the burners in the basement, and we do not see many disasters here. Propane fired water heaters, and whole house heating burners are routine throughout the United States. A propane leak in these spaces could cause a disasterous fire or explosion, yet these disasters are very rare. Why is this so? The answer is good leakproof integrity of the systems, and pilot light systems that do not allow the gas valve to open unless the pilot light is firing, usually with a thermocouple solenoid valve held open (firing permissive) by the heat of the pilot light.

So in my steamboat, I have good leakproof integrity, and the pilot light must be burning before the main gas valve is opened. As a matter of fact, I have a mirror in the bottom of my boiler furnace where most steamboats have an ash pan. I can see the fire, and see the pilot burning all the time I am underway. The spare propane cylinder main valves (not connected to the boat's firing system) can be opened by any fool and no Propane comes out, that is a built in safety feature of modern propane tanks.

When firing at high rates, the propane tanks get very cold (and burner pressure goes down), and some people heat the tanks with hot water, or even steam. This invites a propane safety valve release, and is not proper. When my tank gets too cold I switch tanks, tie a rope on the cold tank and throw it overboard, towing it behind the steamer. The sea water warms up the propane in a few minutes without any chance of overheating the tank.

Any firing system has some elements of danger, and prudent attention to the proper criteria allows for safe operation.