Is their a relationship between boiler volume, pressure and cylinder volume?

[Simon Robinson 4Participant @simonrobinson4]

[Simon Robinson 4Participant @simonrobinson4]

Hi

Please forgive me as I'm a total beginner.

Im in the pre-design stages of constructing a 3.5" gauge coal fired live steam loco. I have not yet decided on the size/ volume of my boiler, but is there any relationship (or ratio) between the volume of the boiler, it's working pressure and the total (combined) volume of the cylinders?

Thanks.

[HopperParticipant @hopper]

As a total beginner, why would you not instead build a tried and tested existing design for your first project?

[JasonBModerator @jasonb]

Take a look at Harris's and Evan's books on boiler making they go into detail about steam usage and what is required to generate that amount of steam such as heating area, grate area, volume, etc.

Alternatively take a look at well known good performing engines and base your boiler design around one of those.

[michael howarth 1Participant @michaelhowarth1]

I have made half a dozen or so small boilers with varying degrees of success but the best were to a proven design so I would concur with the previous post. However, I do enjoy experimenting and I like to know the theory behind things. I have an excellent book entitled "Model Boilers & Boilermaking" by the renowned K.N.Harris which covers the theory and practice of boilermaking. If the theoretical side of things appeals to you I would recommend that you try and get hold of a copy. Failing that I could send you a copy of the first chapter, "General Considerations" if you PM me. A caveat though, K.N.Harris works in old money so if you are a metric man be prepared for some conversions…….principles are the same anyway.

Mick

Jason has beat me to it on recommending Harris so it must be good. There are several copies on a well known site for about a tenner.

Edited By mick H on 29/06/2016 07:40:23

[julian atkinsParticipant @julianatkins58923]

Hi Simon,

It is a bit more complicated than you suggest with many more factors involved, none of which I think you will find in the K N Harris book. K N Harris never built or designed a miniature steam locomotive, and the one he schemed out in the early 1960s was heavily criticised.

There are lots of very good 3.5"g designs that are worthy of study, and if you know which are the very good designs then the design principles, if you can spot them, show the way. Most of LBSC's 3.5"g designs and most of Don Young's 3.5"g designs lead the way.

I could write a lot more but perhaps best first to narrow down what sort of loco you want to build.

Cheers,

Julian

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