410 Hamilton St.,Washington, Ill. 61571
‘Why and how does it work?’
You old time engineers have used an injector most of your life,
but you don’t know how or why it works! At least I haven’t
found a single man who could tell me. Ask any number of Steam
Engine Operating Engineers how and why a boiler, feed water, steam
injector works and you may get as many different answers as you
have engineers nothing in the way of a technical, scientific or
through explanation. You are more likely to get and ‘I
don’t know’ answer or something like this ‘Why any good
engineer knows how it works. You use steam from the boiler through
a steam jet, blowing through a suction jet, that syphons the water
from your supply tank, that in turn is blown through a delivery jet
and into the boiler. Now that was simple, wasn’t it?’
Simple all right, it didn’t tell you a thing. I would still
insist on ‘How and Why’. The explainer starts out again.
‘Well it goes like this’ his voice trails off in thought.
‘We know it works and why it doesn’t work now go see that
fellow over there, he might give you the scientific answer’.
And so it goes. I’ve asked mechanical engineers the question
(now a days they are too young and most likely never heard of the
steam injector for boiler water feed). ‘I’ll go to the
library and look it up and let you know’. ‘I’ll take
the question into the factory and put it up to my fellow
engineers’. I received no help from an inquiry directed at a
well known manufacturer of injectors.
Now, here is what throws them all: the problem simplified is
this: ‘How can you take steam from a boiler, say at 100 lbs.
for example, pick up water with it and force it back into the
boiler on the water side which is under 100 lbs. pressure, and
equal back pressure, also?’
It is easier to see why an EJECTOR (not injector) works, when
you have a pressure differential, or pressure drop, to allow the
thing to work. You can’t pick yourself up with your own
bootstraps, nor are perpetual motion machines possible; this is why
a patent was refused on the injector when first submitted to the
United States Patent Commissioner, until he had seen it work.
Simply stated the injector works because the velocity (speed) of
steam is much greater than the velocity of water. (Steam from the
top of the boiler, water from the bottom of the same boiler) and
the sufficient ‘coolness’ of the incoming water to be able
to condense ALL of the steam. The ability of the greater speed of
the steam, which picks up the water by way of a syphon action, and
drives the incoming water at great speed against the boiler water,
which would flow out of the boiler at a lesser speed, at the same
time the steam must ‘get lost’ condense entirely in the
cool incoming water. Water passing through the injector must be all
liquid so that the incoming water will have enough weight to drive
against the boiler water pressure. Thats why the steam must also
As you know, hot water or a hot injector refuses to work. It
can’t condense enough steam to give the water enough weight to
buck the boiler water, even though it still has velocity.
I started this question as a small boy, when I first saw the
injector work. At the age of 50 (last year) I found the answer at
last! A booklet ‘STEAM ENGINE GUIDE’ available through this
magazine was very helpful.
‘More Power’ to all, and to all in fun I submit this