Injector question

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GORAN ROSEN
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Injector question

Post by GORAN ROSEN » Mon Jun 03, 2019 4:29 pm

Ladies and Gentlemen,
I am aware of the general purpose of the overflow tube of my injectors.
My question is if air entering the tube from below, in any circumstantials can mix with the water being pressed into the boiler? My Britannia 7¼" has two injectors below the cab floor.
Thanks for your information :idea: — Regards,
Göran

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Fender
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Location: Chattanooga TN

Re: Injector question

Post by Fender » Mon Jun 03, 2019 5:11 pm

There is a check valve in the overflow line, which closes from the vacuum created by the injector when it “picks up” (begins putting water in the boiler). If the check valve is leaking, letting in air, then usually the injector fails.
Also, if there is an air leak in the water feed line, this will also cause the injector to fail.
Last edited by Fender on Mon Jun 03, 2019 5:14 pm, edited 1 time in total.
Dan Watson

Asteamhead
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Re: Injector question

Post by Asteamhead » Mon Jun 03, 2019 5:13 pm

Hello Göran,
Don't worry! That's not an issue due to the energy needed to compress and feed the air into the boiler.
Look, even any minor :( leakage (of air) within the water supply from the tender will break delivery of the injector.
Asteamhead

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Fender
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Re: Injector question

Post by Fender » Mon Jun 03, 2019 5:21 pm

The usual source of oxygen in the feedwater is from “dissolved” oxygen already in the water. This can be removed chemically, such as with sodium sulfite, or by heating the water before it goes into the boiler, to reduce its solubility for gases.
Dan Watson

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