This device, sometimes also known as a siphon or jet pump, is used
to fill the engine's reservoir by means of a venturi, much like
an injector. A jet of steam entrains the air within the suction
hose, creating a vacuum that can lift the water several feet. Since
the reservoir is merely at atmospheric pressure, the ejector does
not need to be as carefully balanced as an injector. Assuming no
air leaks in the hose, one merely turns on the steam, waits for
the water to rise to the fitting, and then turn the steam back down
as far as possible, to avoid heating the water too much.
The ejector is a fairly fast, quiet method
of water transfer - Case tells of a test in which an ejector with
a 2" suction line and a ½" steam line lifted water
five feet at 70 gallons a minute, heating it ten degrees F.
The hose needs to be built for suction,
so the that vacuum does not simply collapse the hose. The original
hoses were a hard rubber tube inside a woven canvas jacket and may
be hard to duplicate today. A strainer needs to be attached to the
end, to prevent chunks of debris and small critters from being sucked
into the tank if you're siphoning out of a natural body of water.
Engines that routinely draft water from natural bodies need to have
their tanks cleaned regularly to get rid of sediment.