Boiler Theory
- Thread starter Artie
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Hi again Harry, well for a while the decision was made.... and then I received my copies of the boiler codes, both copper and steel. Extremely well written documents and very helpful in determining my direction. The requirements for this sized boiler are ONEROUS, if I wish to comply with club regulations and as such are able to enjoy insurance cover. I do wish to comply and I do wish to enjoy the insurance cover.
It became very clear quite quickly that I was aiming for something way out of my league. Let me explain, one of the members of the miniature steam association kindly offered to open his workshop doors and show me why this was so.
So I drove 3 hours (each way) to meet Ross and see his absolutely gorgeous, dismantled steam loco. No he didnt dismantle it for me it was due for a boiler inspection, but he did wait til I arrived before reassembling it.
Basically he explained that the boiler I was contemplating was not much smaller than his, which operated 2 50mm (2 inch) bore engines and could tow 16 people with a weight of over 2 tonnes with the carriages included. We discussed the lack of torque required by a (relatively light and small at 7 foot) paddle steamer which has 'slip' when it drives in water and his situation which is mechanically linked to the track with high friction.
It boils down to me not needing the boiler size I thought I did. As such I could drop down into the sub-miniature boiler codes (which Ross was able to supply me as he sells them for his club). Ross's engines where 50mm bore mine are 25mm bore,this makes sense to me.
The requirments for the sub-miniature category is much less stringent and as long as I comply with the following I can be clased as sub miniature. Less than 75 psi working pressure, less than 75mm boiler diameter and 1 litre or less in boiler capacity.
The usual requirements exist for copper tube design etc, but it is a much simpler set up than is required for the larger boiler. Tel, still want that piece of steel tubing?? I no longer need it!
The boiler size mandated is cosmetically too small for the boat so I am building a dummy, more scale looking boiler which is simply a cover for the real thing and a mount for the cylinders/engines. This will allow me to build the boiler as 'spartan' in appearance as it needs to be to simply operate.
A good result, I simply need to source a 220mm length of 75mm dia seamless 1.6mm wall thickness copper tubing. Any Aussies have any ideas on this one? I havent gotten that far yet, Ive just got back from the choo choo ogle (and it was an ogle...wow it was gorgeous!)
Also someone mentioned that you cannot use brass in any capacity in a boiler. This isnt true but when used it must be noted by the boiler inspector on the boiler compliance certificate.
Compliance and certification is still required, that side is no different, but building the boiler itself is much more realistic and therefore less problematic. Incidentally, the boiler is a horizontal fire tube marine style unit if anyone is interested.
In an effort to gain efficiencey from the smaller diameter boiler I may route the firetube through the boiler more than once. This may require a trial build to see. Not sure on this bit yet.
I also walked away from Ross's workshop with a new found respect for model loco engineers! On two fronts... the technical engineeing was of a high order. Simply marvellous. Also on account of the financial investment these guys have in their loco's. In excess of $30,000 aussie bucks isnt unheard of. Smaller 2nd hand machines go for around the $18,000 mark (dependant upon condition and size etc). That alone blew me away.
My thanks to those who contributed to my journey of discovery, to Ross in Echuca (thanks again mate) and to the guys who have drafted up the extremely comprehensive and well written miniature boiler codes.
It all means that I have had a blast, an education and have settled on a safe, sensible, useable result.
th_wav th_wav th_wav th_wav th_wav
*discussion*
It became very clear quite quickly that I was aiming for something way out of my league. Let me explain, one of the members of the miniature steam association kindly offered to open his workshop doors and show me why this was so.
So I drove 3 hours (each way) to meet Ross and see his absolutely gorgeous, dismantled steam loco. No he didnt dismantle it for me it was due for a boiler inspection, but he did wait til I arrived before reassembling it.
Basically he explained that the boiler I was contemplating was not much smaller than his, which operated 2 50mm (2 inch) bore engines and could tow 16 people with a weight of over 2 tonnes with the carriages included. We discussed the lack of torque required by a (relatively light and small at 7 foot) paddle steamer which has 'slip' when it drives in water and his situation which is mechanically linked to the track with high friction.
It boils down to me not needing the boiler size I thought I did. As such I could drop down into the sub-miniature boiler codes (which Ross was able to supply me as he sells them for his club). Ross's engines where 50mm bore mine are 25mm bore,this makes sense to me.
The requirments for the sub-miniature category is much less stringent and as long as I comply with the following I can be clased as sub miniature. Less than 75 psi working pressure, less than 75mm boiler diameter and 1 litre or less in boiler capacity.
The usual requirements exist for copper tube design etc, but it is a much simpler set up than is required for the larger boiler. Tel, still want that piece of steel tubing?? I no longer need it!
The boiler size mandated is cosmetically too small for the boat so I am building a dummy, more scale looking boiler which is simply a cover for the real thing and a mount for the cylinders/engines. This will allow me to build the boiler as 'spartan' in appearance as it needs to be to simply operate.
A good result, I simply need to source a 220mm length of 75mm dia seamless 1.6mm wall thickness copper tubing. Any Aussies have any ideas on this one? I havent gotten that far yet, Ive just got back from the choo choo ogle (and it was an ogle...wow it was gorgeous!)
Also someone mentioned that you cannot use brass in any capacity in a boiler. This isnt true but when used it must be noted by the boiler inspector on the boiler compliance certificate.
Compliance and certification is still required, that side is no different, but building the boiler itself is much more realistic and therefore less problematic. Incidentally, the boiler is a horizontal fire tube marine style unit if anyone is interested.
In an effort to gain efficiencey from the smaller diameter boiler I may route the firetube through the boiler more than once. This may require a trial build to see. Not sure on this bit yet.
I also walked away from Ross's workshop with a new found respect for model loco engineers! On two fronts... the technical engineeing was of a high order. Simply marvellous. Also on account of the financial investment these guys have in their loco's. In excess of $30,000 aussie bucks isnt unheard of. Smaller 2nd hand machines go for around the $18,000 mark (dependant upon condition and size etc). That alone blew me away.
My thanks to those who contributed to my journey of discovery, to Ross in Echuca (thanks again mate) and to the guys who have drafted up the extremely comprehensive and well written miniature boiler codes.
It all means that I have had a blast, an education and have settled on a safe, sensible, useable result.
th_wav th_wav th_wav th_wav th_wav
*discussion*
AlanHaisley
Well-Known Member
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Ian,
As I looked at this site:
I realized that I had no idea what the difference between a "miniature boiler" and a "sub-miniature boiler" were. Could you provide information on the difference?
Alan
As I looked at this site:
ianjkirby said:
I realized that I had no idea what the difference between a "miniature boiler" and a "sub-miniature boiler" were. Could you provide information on the difference?
Alan
Hi Alan, miniature boilers are 76mm or larger, have a capacity larger than 1 litre and the operating pressure is up to the designer (within reason).
Subminiature is obviously smaller than these figures (75mm or less, 1 litre or less and max of 75psi pressure.).
The standard miniature copper and steel codes recognise that these engines and boilers will have people in close proximity. Such as a driver and passengers, and therefore these people need to be protected from ANY eventuality.
The subminiatures will have trouble or in most cases simply wont be able to carry the load and therefore will not have such close proximity..or will be marine use..... as in my case.... and then even further from people.
If anyone has any questions I am happy to refer to the codes for an answer. I wont list any portion of the codes online however, this is copyright area and I wouldnt anyway. If you need them, do as I have and buy them.
Cheers
Artie
Subminiature is obviously smaller than these figures (75mm or less, 1 litre or less and max of 75psi pressure.).
The standard miniature copper and steel codes recognise that these engines and boilers will have people in close proximity. Such as a driver and passengers, and therefore these people need to be protected from ANY eventuality.
The subminiatures will have trouble or in most cases simply wont be able to carry the load and therefore will not have such close proximity..or will be marine use..... as in my case.... and then even further from people.
If anyone has any questions I am happy to refer to the codes for an answer. I wont list any portion of the codes online however, this is copyright area and I wouldnt anyway. If you need them, do as I have and buy them.
Cheers
Artie
Its yours mate, for what I paid for it.... oh, wait...... it was free..... ;D
Done bloke, just gotta organise a way of getting it to you. I'm down the South Coast in a few weeks, might go home via Sydney then Bathurst.
Incidentally, I used your recipe for casting cores again tonight. Do yours come out very dark in colour? Or am I using too much molasses.......
Done bloke, just gotta organise a way of getting it to you. I'm down the South Coast in a few weeks, might go home via Sydney then Bathurst.
Incidentally, I used your recipe for casting cores again tonight. Do yours come out very dark in colour? Or am I using too much molasses.......
Artie said:
Crane are one of the major copper pipe suppliers in Oz. Their website will show you what is available and the standards it is made to. http://www.cranecopper.com.au/sizes/
When you know what spec you need, the best people to approach will be commercial refrigeration companies, commercial air conditioning contractors and larger plumbers. I imagine that what you seek should be negotiable for a six pack.
tel
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Well, the stash isn't as well stocked as it was in days of yore, however I did come up with two bits - either would potentially make a good boat boiler.
T'were me, the bigger piece would be good for a horizontal, the smaller a vertical in, say, an open launch.
T'were me, the bigger piece would be good for a horizontal, the smaller a vertical in, say, an open launch.
Thanks Tel, unfortunately Im limited to a firm max of 75mm od. Im sure you can find a use for these yourself. I have a mate who is chasing up a commercial refrigeration installer who he reckons has what I need (75mm od x 1.6mm or thicker x 247mm). The 247mm length gives me the 1 litre capacity maximum I can use.
Mate, how do you want to take possession of the steel tube? I was hoping to detour through your area next month but it seems I will be short of time. I do the south coast run every month as I have an office in Batemans Bay. If you arent in a hurry I have to pick up a bag of bentonite at some point.
Artie
Mate, how do you want to take possession of the steel tube? I was hoping to detour through your area next month but it seems I will be short of time. I do the south coast run every month as I have an office in Batemans Bay. If you arent in a hurry I have to pick up a bag of bentonite at some point.
Artie
And thanks Bob, as in the prev. post im investigating the refrigeration tube situation as we speak. Good info and I like your valuation of the tubing, if only the world moved on Carlton United Brewerys' back......
Incidentally I was able to lengthen the tubing a little by calculating the volume on the cylinder using the ID, previously I had calculated it on the OD. Every little bit helps.
Artie
Incidentally I was able to lengthen the tubing a little by calculating the volume on the cylinder using the ID, previously I had calculated it on the OD. Every little bit helps.
Artie
