Corin Posted February 2, 2011 Author Share Posted February 2, 2011 Hi Mate, First up, A very big thank you for your time in assisting me to understand this. I do appreciate it, and understand you have no obligation to do so. Wow -30 Degrees! Down here we think its cold if it goes under 0 deg C! You are of course correct in assuming, from my perspective, in all discussions on burner orifices all pressures are upstream gauge, and differential is the same thing as we are discharging to atmosphere. You will also be pleased to know that I may have now reached a clear understanding of Sonic flows and identified and resolved my areas of confusion. I was looking for a restriction or a limit in flow after sonic flow is reached, per Phil's comment at the top of this page. I entered my formula into excel and a series of tabular results, for a 1/16" orifice. I then calculated results from my formula and worked out that for this orifice size the constant is 27.35 (I believe I still need to factor in a friction co-efficient to get this perfect for all orifice sizes, but I will get onto that later.) Suffice is to say with my formula (green dots) and a constant of 27.35 the variance from the tables (brown dots) is less than 1% The curves are perfect. I am very happy with my little formula even if it has little real world application. I wish I had excel when I did the calculations that lead to it! I was looking for a change in flow, but the curve clearly shows none. I then went looking for flow curves for other gases, and found this.My link I then realized the error in my thinking. In my application Sonic flows do not restrict mass flow on increase of pressure as was suggested, they limit velocity and increase density. Order is restored in my world Thanks again Jack, am I on the right track now? My apologies to anyone following this conversation that does not care but I do like to understand a thing! Also keep the messages coming if you have burner questions or questions on Propane in General, I am happy to discuss bottle freeze ups, regulators and their operation, in fact as I said at the top anything to do with propane. Quote Link to comment Share on other sites More sharing options...
Jack Evers Posted February 2, 2011 Share Posted February 2, 2011 I then realized the error in my thinking. In my application Sonic flows do not restrict mass flow on increase of pressure as was suggested, they limit velocity and increase density. Order is restored in my world Thanks again Jack, am I on the right track now? Right on Mate. I love a good empirical equation. We didn't get to minus 30 this morning, but it's minus 29.4 as I prepare for bed so we'll be there tonight, then we're due for a warm up although zero is a few days away. Quote Link to comment Share on other sites More sharing options...
Jack Evers Posted February 2, 2011 Share Posted February 2, 2011 Right on Mate. I love a good empirical equation. We didn't get to minus 30 this morning, but it's minus 29.4 as I prepare for bed so we'll be there tonight, then we're due for a warm up although zero is a few days away. Quote Link to comment Share on other sites More sharing options...
Jack Evers Posted February 2, 2011 Share Posted February 2, 2011 Corin I'd love for you to look at a previous thread about freezing propane and comment on whatever. Heat transport may not be your bag, but perhaps the composition of the LPG we call propane is. Quote Link to comment Share on other sites More sharing options...
Corin Posted February 3, 2011 Author Share Posted February 3, 2011 I have not read the previous thread, do you have a link? Following is some basic information and properties on LP Gas that I will use in discussions regarding cylinder freeze ups (as opposed to regulator freeze ups.) Also is a general explanation of how vaporisation works in a propane cylinder Firstly Composition: In Australia and The USA LP Gas used in industry and for home heating (generally speaking) is 90% or more propane. In New Zealand and in Australian Auto Gas, it is a blend of Butane and Propane commonly a 50-50 mix, although there is a huge amount of variance in Austalian Auto Gas. In the Pacific Islands it is normally 90% + Butane. Before you go any further check what the mix is in your part of the world, because it will make a difference. At this stage I will only be discussing Propane, and high percentage mixes of Propane. Think of Propane just as you would water. It is colourless, odourless, (and probably tasteless ), it has three states of matter, Solid (like ice), Liquid (like water) and Vapor, (like steam) (we will ignore that it is flammable for the time being.) At temperatures below about -190 C (-374 F) it is a solid, just like water below 0 C (32 F) is Ice. If we warm it up above ---190 C (-374 F) it melts into its liquid phase. we can hold it in a cup (if we could survive the cold). OK so lets keep warming it up.... at -42 C (-44 F) it starts to boil. just like we cannot heat water above 100 C (212 F) no matter how big a fire we put under it, we can't heat propane liquid above -42 C. It simply boils into its gaseous phase. For every volume of liquid that boils off we get 274 volumes of vapour. These are facts,but we are overlooking something, this is for atmospheric pressure at sea level. Of course it is possible, to heat water above 100C without it boiling, by heating water in a sealed vessel we create pressure, this pressure prevents the water boiling. Think of a pressure cooker or the radiator in a car. http://en.wikipedia....ressure_cooking The more we heat, the higher the pressure will be. By putting the liquid Propane in a container capable of holding pressure, we can thus prevent it boiling when temperatures rise above -42C (-44F) as temperature increases so the pressure will increase too just like in a pressure cooker or a car’s radiator with water. At -1C (30F) The pressure in our propane cylinder will be 400 kPa (58 PSI). At room temperature 15 C (59F) the pressure in your cylinder is about 700 kPa (100 PSI) the size of the cylinder has absolutely no bearing on this, whether it is a few pounds of product in your 20# cylinder, or a correctly full 80 ton tank if both are at the same temperature they are the same pressure. Ok so what happens if we remove some gas? It should be quite obvious if you have read and understood the information above , that if we release all pressure quickly, the boiling point of the product reverts to -42 C (44 F), the liquid will boil rapidly. It needs energy to do this and this energy comes in the form of heat in the liquid and the surrounding air. The temperature of the liquid will drop to -42 as the pressure reaches zero gauge. To put this in perspective, if the valve on a 9kg (20 #) cylinder is opened to full (at room temp), it takes about 4-5 minutes for the liquid temperature to drop to -42 and the pressure to reach 0 PSIG and at this point the amount of vapour being produced is very small, governed only by the amount of heat that can enter the cylinder from the air around the cylinder. Think of what happens if you remove the cap off your radiator. The superheated water flashes to steam and boils off. This process is actually almost the same. (if the radiator had more water in it) So what if we only take out a small amount of vapour from our cylinder at room temperature? Only a small amount of gas removed will drop the pressure slightly in the cylinder. Slightly dropping the boiling point and causing some liquid to boil off the energy for the gas to boil comes from the heat within the liquid, and whatever heat can be conducted from the surrounding air into the liquid in the cylinder. If we take out more gas than what can be boiled off by the heat in the surrounding air, then the cylinder starts to “freeze” Pressure will drop, temperature will drop, first condensation forms on the outside and soon this condensation starts to freeze. The propane does not freeze it just can’t boil fast enough. Whenever we size how many cylinders or tanks and what size to use on a propane installation we need to consider this phenomenon. We do so based on gas consumption required and ambient temperature. It is also important to consider how much liquid is in your cylinder, as heat from the surrounding air must be transferred into the liquid, so hence the wetted surface area is critical. Normally cylinders are sized at 30% full. Think about trying to boil a pot of water by putting a heating element around the top of the pot where there is no water. The effect will be negligible. Insulating tanks is clearly silly, as heat cannot enter to boil the liquid propane, this will make things worse. Increasing the air movement around the tank will improve vapourization, in much the same way as air through a radiator helps cool the water inside, heat energy from the air passing past will transfer into the liquid better than still air, which will chill near the cylinder. Heating the cylinder is a clear winner, except that when things go wrong they really go wrong, More on this later maybe... There are appliances available, called vaporizers, specifically for this purpose, normally for industrial applications, but there are small models. I hope that all make sense, I am happy to answer any specific or general questions on this subject, and can provide more detailed information on request. Lets have some questions! Quote Link to comment Share on other sites More sharing options...
Jack Evers Posted February 3, 2011 Share Posted February 3, 2011 Here's the link, Corin. My stuff comes in about post 34.Says much the same as you. Sorry I used BTU's and pounds and degrees F, but heck - minus 40 is the same either way. Quote Link to comment Share on other sites More sharing options...
Fosterob Posted February 3, 2011 Share Posted February 3, 2011 Thank you for such a detailed description of propane. I would like to make one of your burners, should I be able to get that venturi at the local propane dealer. I will probably also need to upgrade hose and regulator but will have to check. Rob Quote Link to comment Share on other sites More sharing options...
Corin Posted February 3, 2011 Author Share Posted February 3, 2011 Here's the link, http://www.iforgeiro...erent-solution/ Hi Jack, interesting thread! Not so sure I would be comfortable living next door to a few of those folk. Your info is good, especially the fan calculations. We have used fans before to get that little bit more... it is interesting to know how much. I made a comment. I could not comment on everything I wanted too. Not enough hours in the day! Don't be sorry about BTU Pounds etc.... really I work in any units, here it is mj/h, kPa, Kilograms, liters and Deg C. we import heaps of equipment from USA and most stuff that comes here from Europe is kilowatts and bar, I am very used to conversions! Take care mate, I hope it is starting to warm up for you. We hit 45 C today. Looking forward to cooling down! Quote Link to comment Share on other sites More sharing options...
Jack Evers Posted February 3, 2011 Share Posted February 3, 2011 Thanks, Corin. I also know units, kidding about the American units, spent 10 years globetrotting for industry short courses. taught me how different metric systems are. SI which doesn't recognize centa and deca, etc. joules, watts, bars, pascals, kg/cm^2 etc. Taught some courses to Libyans in Canada at a time that I couldn't go to Libya and they couldn't come here. They found Canadian metric so confusing they wanted me to stay Imperial (the materials I used were in both systems). Yes we're on the western edge of this massive front and for us it's moving out and warming up. Minus 37 F yesterday morning with a minus 61 wind chill. Minus 14 when I went to bed, minus 7 when I got up. We'll get to near freezing today. Quote Link to comment Share on other sites More sharing options...
SoCal Dave Posted February 5, 2011 Share Posted February 5, 2011 Have you ever test or experimented with a ribbon burner in one of your forges? Quote Link to comment Share on other sites More sharing options...
Corin Posted February 6, 2011 Author Share Posted February 6, 2011 what we refer to as a ribbon burner in the gas industry is quite different from what I have seen in forges. In short I do not have much experience at all with burners with blowers of any type. I have read up on these burners for forges and they look very interesting. In my opinion, I rather have a forge that does not require a blower, and is really easy to make. There are spots in my forge that are hotter than others, but that is actually quite useful, as it allows you to heat thicker sections more than thinner, once you know where the hot spots are. I see little benefit in ribbon burners for what I do. If I ever get around to making a long heat treat forge (24"-36") I will definitely be considering these though. Quote Link to comment Share on other sites More sharing options...
Nakedanvil - Grant Sarver Posted February 6, 2011 Share Posted February 6, 2011 Some interesting threads on forge ribbon burners:RIBBON BURNER FORGE BUILDRIBBON FORGE BURNER Quote Link to comment Share on other sites More sharing options...
Corin Posted February 7, 2011 Author Share Posted February 7, 2011 Some interesting threads on forge ribbon burners:RIBBON BURNER FORGE BUILDRIBBON FORGE BURNER Very Useful links, thanks mate! Quote Link to comment Share on other sites More sharing options...
Dave Hammer Posted February 9, 2011 Share Posted February 9, 2011 How many gallons of propane can safely be put in a hundred pound tank. If more than that was put in, how should it be handled? I may have missed it in the text somewhere, but can you tell us specfically WHERE you buy your venturi's? Quote Link to comment Share on other sites More sharing options...
Corin Posted February 10, 2011 Author Share Posted February 10, 2011 How many gallons of propane can safely be put in a hundred pound tank. If more than that was put in, how should it be handled? I may have missed it in the text somewhere, but can you tell us specfically WHERE you buy your venturi's? Hi Mate, Firstly, the safe fill level is 80% of the total internal capacity of your tank. You will notice the capacity is stamped with the other information around the top of the cylinder. Normally this figure will have the Prefix WC (water capacity)and then a figure in Gallons of pounds. For Propane, there are 4.2 Lbs per Gallon Therefore, for a normal 100# cylinder you should be filling with 23.8 Gallons If you overfill, there are serious repercussions. As the liquid warms it expands, like mercury in a thermometer. When there is no more vapor space above the liquid, the pressure builds rapidly (the liquid itself cannot compress). At 375 PSI the relief valve opens and liquid is released. The liquid expands 274 times at atmospheric pressure and only about 3% gas to air mix is required to make a nice explosive mix. A very small release can be very dangerous very quickly, particularly in a confined space. I will post a video that illustrates this quite well. Ignore the news reporter, this was a typical overfill accident. A very long time ago through careful calculation and experimentation, taking into account worst case scenarios it was decided the safest fill level was 80%. I see no point exceeding it, though you are of course free to do as you please. I buy my short pattern inspirators from Gameco (and there is a conflict of interest because I also work there) My link The part number is NGB-1 and for what they are they are quite expensive.2 Ipswich.mpg Quote Link to comment Share on other sites More sharing options...
Dave Hammer Posted February 11, 2011 Share Posted February 11, 2011 Hi Mate, Firstly, the safe fill level is 80% of the total internal capacity of your tank. You will notice the capacity is stamped with the other information around the top of the cylinder. Normally this figure will have the Prefix WC (water capacity)and then a figure in Gallons of pounds. For Propane, there are 4.2 Lbs per Gallon Therefore, for a normal 100# cylinder you should be filling with 23.8 Gallons If you overfill, there are serious repercussions. As the liquid warms it expands, like mercury in a thermometer. When there is no more vapor space above the liquid, the pressure builds rapidly (the liquid itself cannot compress). At 375 PSI the relief valve opens and liquid is released. The liquid expands 274 times at atmospheric pressure and only about 3% gas to air mix is required to make a nice explosive mix. A very small release can be very dangerous very quickly, particularly in a confined space. I will post a video that illustrates this quite well. Ignore the news reporter, this was a typical overfill accident. A very long time ago through careful calculation and experimentation, taking into account worst case scenarios it was decided the safest fill level was 80%. I see no point exceeding it, though you are of course free to do as you please. I buy my short pattern inspirators from Gameco (and there is a conflict of interest because I also work there) My link The part number is NGB-1 and for what they are they are quite expensive. I had 3 tanks (100#, 40# and 20#) filled (earlier this week) and the filling station grossly overfilled (at least) the 100# tank. They put 27.3 gallons in it, and it probably was not completely empty. I suspect the other two tanks were overfilled also (there was still a little gas left in each tank, and the attendant put in the amount of gas that should have been put in if the tanks were empty). It was, and has been, cold since they were filled. Yesterday, I forged all day and used 20# from the 100# tank (so it should be safe). I will forge with the others before it warms up much to get there content down also. I need to run these tanks all the way empty before I get them filled the next time.... and watch the filling station do their work. Actually, it would be best if I weighed them empty once to find out how much the tanks weigh, then weigh them before I take them in to know how much gas is still in each tank. I then can calculate how much gas the filling station should be putting in each tank. I couldn't find your aspirator (your brand) in the United States (actually, I couldn't find your aspirator online in their catalog), so I found another source for a similiar one here... Thank you for your information.... Quote Link to comment Share on other sites More sharing options...
pkrankow Posted February 11, 2011 Share Posted February 11, 2011 So...if I have no other choice than to transport a cylinder in a car, will leaving a window partially open be enough to prevent this possibility? I am a non-smoker, so that's not an issue. Phil Quote Link to comment Share on other sites More sharing options...
Rhrocker Posted February 13, 2011 Share Posted February 13, 2011 Is there a tank size limit for using inside a commercial shop building? I guess this could be a state thing, but the actual danger considerations should be the same wherever you are. I've heard that you can be fined if the inspector (A railroad guy?) finds that you're using tanks larger than 5 gal (40# I guess). But this was just hearsay. My three forging tanks are 90 pounders, so of course I don't use them in my shop. Has anyone on the list been fined by these guys? Details? Quote Link to comment Share on other sites More sharing options...
Corin Posted February 13, 2011 Author Share Posted February 13, 2011 So...if I have no other choice than to transport a cylinder in a car, will leaving a window partially open be enough to prevent this possibility? I am a non-smoker, so that's not an issue. Phil If your cylinders are filled correctly and upright, (If possible in the trunk of the vehicle) The chances of having an issue are probably less than actually driving the car. Dilution air is not a bad thing in any case, Is there a tank size limit for using inside a commercial shop building? I guess this could be a state thing, but the actual danger considerations should be the same wherever you are. I've heard that you can be fined if the inspector (A railroad guy?) finds that you're using tanks larger than 5 gal (40# I guess). But this was just hearsay. My three forging tanks are 90 pounders, so of course I don't use them in my shop. Has anyone on the list been fined by these guys? Details? In Australia for this type of usage in a Garage type workshop the maximum size is on 20# cylinder inside, with no more than 100# of total storage inside and outside on the property. for a factory or warehouse type situation it is on 45kg cylinder per 540 Square foot of floor area. It will no doubt be different where you live, I cannot help, but I am sure someone else on here can. Regards Corin Quote Link to comment Share on other sites More sharing options...
Rhrocker Posted February 13, 2011 Share Posted February 13, 2011 Thanks Corin! I'll go surfing on the net also and see what the ol State of Texas allows. I'd sure hate to get hit with a fine of 50,000,000 for a violation like that. I'd be making trivets for the next several weeks! :blink: Quote Link to comment Share on other sites More sharing options...
Rhrocker Posted February 25, 2011 Share Posted February 25, 2011 Thanks Corin! I'll go surfing on the net also and see what the ol State of Texas allows. I'd sure hate to get hit with a fine of 50,000,000 for a violation like that. I'd be making trivets for the next several weeks! A bit of a follow up here. I talked to the man that inspects my building (every 3 years or so). He is with the Railroad Commission of Texas, Safety Division. I asked him questions about what is and is not allowed in a biulding, home, garage, and so forth. He took my list of questions and wanted to check them out by the book so that he didn't give any bogus info. I told him that I sure hope I wasn't red flagging my business by doing this inquiry, and he assured me I wasn't. He's going to stop in next time he's in my area and go over my situation here, and tell me if I need to make any changes. He promissed no citations! Apparently the fines can be rather stiff if you're not to code on some things, and I'm wanting to avoid that at all costs. I'll pass on the info I get from him, but keep in mind that this is a Texas LP inspector, and your state may not be a strict, or maybe it is. I did learn one thing for sure, and that's that I can't have one of my 5 gallon (40 lb?) tanks inside the building while using it. It needs to be sitting outside, with piping running through the wall. There needs to be a regulator at the tank also. I'll get more on that later on, like "what is the fine if I'm found forging inside my shop, with my propane tank saddled up besides me. To be continued, (if you want to hear it). Robert Quote Link to comment Share on other sites More sharing options...
Corin Posted February 25, 2011 Author Share Posted February 25, 2011 To be continued, (if you want to hear it). Robert Keep us posted! Quote Link to comment Share on other sites More sharing options...
Rhrocker Posted February 25, 2011 Share Posted February 25, 2011 Thanks Corin, I sure will. Also, consider something else the inspector said; You're chances of being "caught" in violation are pretty slim due to manpower shortages unless you actually have an incident/accident involving LP gas. This is where the authorities step in. The local authorities notify the officials of your state of an accident involving severe injury and/or loss of life, and/or property losses. This perks their attention, and a team is sent out to investigate and make a report. If you are found to be in violation, the fines can get real bad real fast. Now I realize that this isn't a fun and interesting post, and involves very little artistic value, but it is something that could potentially put a smith out of business and worse, meaning the fines could reach extremently high limits very quickly. Therefore, it's up to us to learn as much as we can about this potential hazzard, and correct it if possible before it destroys someones workplace, or life. More as I find out more. Robert Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted February 25, 2011 Share Posted February 25, 2011 Perhaps of greater concern to a lot of us "non-commercial smiths": If something happens and your homeowners insurance company can determine that you were not following code they can and will disallow any payment on the incident! Car transportation, I have seen heard and smelled BBQ sized propane tanks venting in a closed car one summer in a supermarket parking lot. It's easy to make it much safer though: simply remove the battery and alternator from the car before placing the tank inside. Cars tend to have a lot of make and break electrical contacts, not a good thing around possibly explosive gas-air mixtures. Quote Link to comment Share on other sites More sharing options...
pkrankow Posted February 26, 2011 Share Posted February 26, 2011 Perhaps of greater concern to a lot of us "non-commercial smiths": If something happens and your homeowners insurance company can determine that you were not following code they can and will disallow any payment on the incident! Car transportation, I have seen heard and smelled BBQ sized propane tanks venting in a closed car one summer in a supermarket parking lot. It's easy to make it much safer though: simply remove the battery and alternator from the car before placing the tank inside. Cars tend to have a lot of make and break electrical contacts, not a good thing around possibly explosive gas-air mixtures. You got the spirit of typical legislation, but I think you missed the spirit of this discussion (probably deliberately) I am interested in Rhocker's inquiry results as well, even if it is not the same general region. Phil Quote Link to comment Share on other sites More sharing options...
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