injectors

[Garry ColesParticipant @garrycoles69390]

[Garry ColesParticipant @garrycoles69390]

Hi, This might be a stupid question and I might get a stupid answer. But why does the water to the injector not drain the water from the tank when the steam supply is off, or do you need a another shut off valve in the water supply line as well as the steam supply line.

Garry

[RMAParticipant @rma]

Yes, you do need a valve for the water.

[Garry ColesParticipant @garrycoles69390]

Thanks for that. I thought you must, but my plans only mentioned the steam supply valve.

Garry

[Paul LousickParticipant @paullousick59116]

There are also lifting injectors which suck the water vertically and do not need a valve in the water supply. I have used them on full size engines but have not seen them used on models. Probably because of the higher steam pressures used in full size engines.

Paul.

[Brian OldfordParticipant @brianoldford70365]

The water valves on many standard gauge engines are at just the right height on which you can bruise your calf or ankle.

[Harry WilkesParticipant @harrywilkes58467]

Garry if you do fit a water shut off valve make sure the bore of the valve doesn't restrict the water flow

H

[duncan webster 1Participant @duncanwebster1]

If it's time for silly questions, could you take the overflow from the injector back above the level of the tank so that it didn't drain the tank. I realise you wouldn't then be able to run water through the injector to cool it if it got too hot

[Another JohnSParticipant @anotherjohns]

A lifting injector is "the same as" a non-lifting one, with the exceptions:

– a lifting one needs to work as an "ejector" to lift the water up into the injector; (some full size ones lack this ability) – it means that the overflow needs to be quite large to reduce back-pressure;

– any injector needs to not heat the incoming water too much; in our small injectors, there's a large surface area to water volume as compared to the full-size; having water drip through it keeps it cool, so the steam from the steam cone has a better chance of condensing.

Duncan – on one coal-fired steam crane I used to supervise over here in Canada, one of the volunteers had trouble with the Hancock Inspirator, which should have been self-priming, and lots of steam went out the overflow, which was plumbed BACK into the water tank. Water was low in the boiler; I could not get the injector to lift; the water tank was very warm to the touch; got a fire hose to fill the water tank with cold water, and things were back to normal.

Anyway, just my tuppence on this beautiful day.

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