[modeleng] Re: Injector selection

Hi John,
Thanks for this, it's exactly what I was after!

The spreadsheet is very useful and I can completely see what you mean 
about the number 2 injector being too large [by quite some way].

Yours,


Rich.


On Fri, 11 Jul 2008, John Baguley wrote:

> Hi Rich,
>
> Speaking as a 2½" gauge man, a No.2 is really too large for a 2½" loco
> although people do fit them. It puts the water in fast but drops the
> pressure rapidly as well. They use too much steam for the small boilers
> to keep up with.
>
> I've made  an 8oz and a 4oz for my Helen Longish which work but I
> haven't managed to get them to run dry yet  - more experimentation
> needed! I can leave the 4oz running with no real  drop in boiler
> pressure. The original idea was that the 4oz could be left running most
> of the time and be used instead of the axle pumps and the 8oz used for
> more 'serious' topping up.
>
> I did enquire about No.1's at my local stockist and was told that the
> smallest they will sell is a No.2 as they cannot guarantee reliability
> with anything smaller. Thinking about it, I don't think I've ever seen
> anyone advertising a No.1?
>
> I've read that as a rough guide the injector should be able to supply
> about twice the water consumption of the loco when running.
>
> Out of interest I devised a spreadsheet to work out the water
> consumption based on cylinder swept volume, wheel diameter, speed, and
> cut off. You can download a copy from here:
>
> http://www.baggo.copperstream.co.uk/me/injectors/Injector%20size%20calculator.xls
>
> John
>
> R.L. Roebuck wrote:
>> Hi there All,
>>
>> What is the general opinion on what size of injector to fit to what type
>> of locomotive?
>>
>> Looking at the different common sizes out there:-
>>
>> * Number 2 (11 UK fluid oz water/min)
>> * Number 3 (16 UK fluid oz water/min)
>> * Number 4 (22 UK fluid oz water/min)
>> * Number 5 (2.7 UK pints water/min)
>> * Number 6 (4 UK pints water/min)
>> * Number 8 (1 UK gallon water/min)
>>
>> ...is a number 2 injector too large to fit to a 2.5" gauge locomotive?
>>
>> Do many people fit two injectors, to allow for the differing needs of
>> continuous running and end to end running?
>>
>> I tried searching on the 'interweb', but unusually seemed to draw a blank
>> - am I just looking in the wrong places?
>>
>>
>> Yours,
>>
>>
>> Rich.
>> PS Given the sometimes global nature of our discussions, if it helps...
>>
>> 1 US f.oz = 29.6 ml
>> 1 UK f.oz = 28.4 ml
>> 1 US gal = 3.79 l
>> 1 UK gal = 4.55 l
>> 1 UK pint = 568ml = 1.20 U.S. liquid pints = 1.03 U.S. dry pints
>>
>> PPS Why does no-one seem to make a number 1 injector?
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>>
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