Pressure volume product

[Half centreParticipant @halfcentre]

I am thinking about a project involving a return flue boiler. The' firebox ' is simply the first section of the U shaped flue. The flue is in effect a firetube. The water operating level was usually a fairly shallow covering over the top of the flue. The latest boiler regulations refer to the 'total internal water volume' when calculating the pressure volume product. Would anyone know if there is anything different about the concept of 'total internal water volume' with respect to such a boiler?

Many thanks

Martin

[Half centreParticipant @halfcentre]

Total internal water volume?

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Total internal water volume is usually interpreted as the maximum amount of water contained if boiler was filled to the absolute limit of capacity . ie no steam space at all .

Not a very meaningful concept .

[David LittlewoodParticipant @davidlittlewood51847]

Well, steam is still water (H2O), and I imagine the writer of the regulations had to use some figure which was capable of measurement. If you fill the boiler with liquid water it is easy to determine its capacity, but if you try to define some arbitrary typical usage level it would be impossible to have a useful definition.

David

Edited By David Littlewood on 20/01/2013 19:15:39

[Half centreParticipant @halfcentre]

Thanks gents – so in this case as the firetube/flue can't be filled with water than this is not part of the calculation?

Martin

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Hi Martin ,

Thanks gents – so in this case as the firetube/flue can't be filled with water than this is not part of the calculation?

That's correct .

In practice minor details of boiler design are sometimes ignored for a first estimate – using the simple external dimensions of boiler will usually give an adequate and safe figure which can be refined if nescessary .

Michael Williams .

Edited By MICHAEL WILLIAMS on 20/01/2013 20:21:03

[Half centreParticipant @halfcentre]

Thanks Michael – I am trying to stay within the 3 bar litre limit, the flue will occupy a significant portion of the total internal volume of the boiler so it will effect the calculation.

Martin

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