boilers ?

[antopia]

Geoff,
you are doing a lovely job,its nice to see the boiler comming along,
I have not had time to finish my MB22 engine but have 2 weeks off so might get chance
then make my own boiler,its always nice to see ones own work come to life.
btw yellow ends to the flame is not enough primary air in the mixing chamber,
which leads to co2 production.

please can you tell me the bar litres or your boiler or mls and working pressure as I am trying
to get enough info to ask a model boiler tester why you have to resort to an insurance company my info suggests you should not have to.seeing as I work with model boilers
I am in a position to ask.   
Regards
Steven

[R.G.Y.]

Steven,  I through I wouldn't get into the workshop over Christmas how wrong. Christmas day assembling all the toys, boxing day repairing them.
My boilers total capacity .4 of Liter working pressure 2 Bar max
 = .8 bar-liters.  The reason it's so small is,that is all the pipe I had at the time.  One inch pipe 36inches long = .5 liters. Eighteen inches =.25 liters  The reason for the certificate it is a club requirement on our sailing water in a theme park. 
Yes I am having trouble with the burner, when I increase the air some of the flames go out. I drilled out a jet .03mm then the flame started is burn about an inch from the hole, and some flame out again. I think the hols are to small. So I plan to solder a strip of brass over the existing holes to increase the thickness of the pipe. As I have read that the holes should not more than the thickness of the tube. Dose that sound right to you. Geoff. Or any one else.

[steamboatmodel]

We need Sandy C, or Bogs.
regards,
Gerald.

[antopia]

Hi Geoff,
your gas system
gas need a certain amount of air to burn so yellow tips indicate too much gas
the thing to do is where the jet is located should be some air holes file these out
carefully to bring about the blue flame,
now you should have a flame only just above the metal tube , now I am not the best for
your type of burner but, now you have increased the size of the jet you will have too
much velocity of gas and air hense the 1" flame
so you need to throttle back the velocity.ie a finer needle jet on the tap or change the jet.

on my burner tube I have 2 holes and the jet is placed inside these holes if you make the jet movable then you can vary the position of the jet while in use.
try it sometime it is quite apparent what happens to the flames

if you get the gas velocity too slow it will burn back inside the burner if the plate is
too thin or it will just go out.

increasing the hole size i my opinion is not the best option instead slit the hole so it is fan shaped this is normal for 16mm gauge internally fired locos and works very well.

normally I believe a number 3 or 5 jet is used for your type of burner
I use a numer 8 jet for my ceramic burners
if reading correctly (0.3) you have a number 12 which I feel is far to large
and you may have to replace it.

Number 3 which has a 0.15mm dia jet bore
Number 5 which has a 0.2mm dia jet bore
Number 8 which has a 0.25mm dia jet bore
Number 12 which has a 0.3mm dia jet bore
Number 16 which has a 0.35mm dia jet bore

had chance to run my MB22 engine on air( cycle pump) so even I got time to play.

Thanks for the boiler info
I will agree with the .8 bar litre
should be pressure tested to 2x working pressure or 4 bar nearly 60 psi
I will have to ask to how much the steam test is, figure I have here is not more than 10% rise.

when I return to work I will be asking many questions as
under 3 bar litres I am sure it does not come under the CE ruling,the wording I have
is "best engineering practise" but we will see.

Regards
Steven

[derekwarner_decoy]

Hi PD's....& yes Gerald...I too would sincerely love it if we could get Sandy Campbell & bogstandard back posting as they did 

I am sure both gentleman posted words to the effect ....'that a yellow to red flame is a carburising flame principally caused by a lack of oxygen & hence incomplete combustion'

Again from memory it is the venturi we are creating to draw the optimal amount of air [oxygen] into the gas path & hence the bluish tipped flames

I have had to format my PC C drive so have lost many of my favourites.....but we recently had a few postings from an Australian engine & boiler manufacturer.......in their Melbourne WEB page was an interesting procedure detailed out for setting the burner flame height......

Derek

PS ....here is that site......http://www.modelcomponents.com.au/

[R.G.Y.]

Good imformation thank you all. I have air holes just behind the jet they were not clear on the last photo. (see the latest, the ajuster is hxeagonal). I was just too impasant it is now a lot better. Derek will be pleased to know it will be instaled in a rat infested hulk. Geoff

[antopia]

Geoff,
looks like you have it working now
well done.
burners are always a  little finicky
Regards
Steven

[R.G.Y.]

Seven, Yes I kept the bigger burner drilled another row of holes on the top reducing the gas pressure. The flames are longer than shown, the gas had almost run out by the time I had the camera ready. Geoff

[R.G.Y.]

I have worked out my costs for the boiler. £140  I did acquire a lot of it for nothing it's true but but if every thing had been purchased I don't think it would have exceeded £200. Roll on the new year I can get back in the shop.Geoff

[R.G.Y.]

I am now building the model to flt it in. So the posts will be in construction ( Duke of Devonshire) from now on. R.G.Y.

[R.G.Y.]

Well one more post, Eddy said things have been too quiet of late. the boiler and engine in the Hull. Geoff

[R.G.Y.]

Good news, on seeing my boiler in the flesh the club boiler inspector said no problem. Bring it to the test day and it will be tested.  He was ether impressed or he things it will fail!!! Geoff

[R.G.Y.]

I have made a new burner for this boiler. Had trouble keeping the holes near the jet alight. After numerous attempts to get the mix right and the length of flame. I thought the problem was the tube was to small a diameter at 1/2". The new 5/8" tube has cured the problem. I have also moved the holes down the tube by 20 degrees, this plates the flame to the base of the boiler tubes. Geoff

[Brooks]

My experiments with evening the flame length of the Accucraft poker burner (less than 1/2" diameter): The velocity of the gas is too great as the gas/air mixture enters the poker. The result is that the flame is long at the end of the poker, and short at the start. Fast gas has low pressure, slow gas has higher pressure - as the gas hits the closed end of the poker, it slows, the pressure increases, and the gas shoots out of the slots making a high flame.  This can be cured by inserting a turbulator of some sort into the poker. The resistance provided by the turbulator slows the gas, increasing it's pressure (pressure and velocity are inversely corrolated). My turbulator is simply a twist of metal screen slid into the poker; fancier ones are cone-shaped with roughening grooves.

So, a narrow diameter poker can be made to light along it's entire length if the gas is slowed as it enters the poker.

A more elegant solution, used by commercial gas appliances, is to make the poker conical in section instead of cylindrical (wide end of the cone at the far end of the poker). This automatically slows the gas as it enters the poker, the opposite phenomenon to a garden hose nozzle (which narrows, and trades water pressure for higher water velocity).

Hope this helps.

[R.G.Y.]

Brooks, That explains it. The larger tube is OK for this boiler. If I need a smaller one again I will bear this in mind. Thank you. R.G.Y.