Injectors

[John Andrews 2Participant @johnandrews2]

G'day,

I am building a 5 in gauge loco. Boiler is 150mm dia by about 800 mm long.

Cylinders (2) are approx 42mm dia x 56 mm stroke.

Drivers are 109 mm dia.

I wish to fit two injectors. Can anybody recommend what size they should be?

Can anyone recommend injectors that actually work? I have tried two separate types (different makers) in my Marie E, and neither work.

[John Andrews 2Participant @johnandrews2]

Sizes of Injectors

[Nigel BennettParticipant @nigelbennett69913]

A couple of the "Standard No.4" jobs should deliver enough – or fit a No.3 and a No.4. You can probably leave the smaller one on a lot of the time that the loco is working fairly hard.

Your failures on the Marie E may be nothing to do with the injector itself; a number of possibilities can be as daft as fitting it the wrong way round, or inadvertently missing out or mixing up the delivery/steam cones! Other possibilities are inadequate steam supply, contorted delivery pipes, insufficient throughput of the boiler check valve, leaking check valve, too hot a water supply, restricted water supply….I would eliminate all those possibilities first before condemning your injectors.

If it still fails, you need to try it out on somebody else's loco with a working injector – or at least borrow a known-to-work one first.

[SteamgeekParticipant @steamgeek]

Don't forget a leaky pipe or worn valve that allows air into the line, injectors are not particularly tollerant of air in the water supply.

I run 2 no4's on a three cylinder loco and find them more than adequate, and a single no4 on a Torquay Manor which also does the job

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