GAMEWELL DIAPHONE Type B
Additional pictures and more information.
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Left:
This is a side view of the diaphone cylinder assembly. It shows a 1/4"
NPT pipe plug in the test port. For intial setting up, remove this plug and
insert a 0-60 PSI gauge here. This picture also shows one of the two motor
air exhaust ports just to the right of the test port. In operation, a small
portion of the total air consumed drives the piston back and forth. This air
exhausts here. As you can see, the resonator is made from rolled copper sheet,
silver or hard soldered into a cast bronze front flange. The cylinder assembly
and back cover are cast iron.
Right:
Looking into the brass cylinder with piston re-moved. This picture shows the
speaking slots in the smaller section of the cylinder, the motor air inlet
ports just where the cylinder diameter increases, and also the three slots
in the motor section as well as (around the outside edge) the ports that connect
slots one and three of the motor section. Between the two studs is a recessed
section of the outer cast iron hous-ing which becomes the exhaust port when
the back cover is in place.
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Left:
This picture shows the correct way to remove the diaphone piston, by inserting
a 1/4 X 20 screw or bolt into the center tapped hole in the piston as
a convenient handle. It is very important, as these pictures imply, that
the air supplied to a diaphone should be clean and free of any metal chips
or scale or other material which might score either the piston or the
cylinder. The piston in this diaphone is aluminum.
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Left: Type
B Diaphone dimensions.
To
sound this diaphone adequately, you will need at the very least a 60 gallon
receiver, and performance is better with a 120 gallon receiver. The typical
set up for type B diaphones when installed in fire stations calls for
a pair of 350 gallon high-pressure receivers and a high capacity regulator
after the solenoid valve to supply reduced pressure air to the horn. This
provides adequate reserve for sounding a number of coded fire alarm box
location signals in succession without losing pressure at the horn. When
setting up the diaphone, take a measurement of pressure at the test port
on the side of the cylinder assembly while it is operating, and if necessary,
adjust the regulator so that 40 PSI shows on the gauge. A 60 gallon receiver
will give you several good honks of a few seconds' duration. Receivers
smaller than 60 gallons will probably not give very satisfactory performance.
This is the classic fire station diaphone, used on many fire stations and other public build-ings throughout the USA for many years. It is exactly the same as the larger diaphone foghorns except that it has one common air inlet port to supply both speaking and motor air, whereas the foghorns have a separate motor air inlet. See article on Gamewell diaphones elsewhere on this website for detailed information about these horns. Slightly reducing the pressure suddenly at the end of the blast will make this diaphone terminate its signal with a grunt as does a type F foghorn. Sustaining the lower pressure will cause a two-tone effect similar to that of an F2T foghorn. The actual horn frequency is largely, (but not exclusively) determined by the operating air pressure.
This is the classic fire station diaphone, used on many fire stations and other public build-ings throughout the USA for many years. It is exactly the same as the larger diaphone foghorns except that it has one common air inlet port to supply both speaking and motor air, whereas the foghorns have a separate motor air inlet. See article on Gamewell diaphones elsewhere on this website for detailed information about these horns. Slightly reducing the pressure suddenly at the end of the blast will make this diaphone terminate its signal with a grunt as does a type F foghorn. Sustaining the lower pressure will cause a two-tone effect similar to that of an F2T foghorn. The actual horn frequency is largely, (but not exclusively) determined by the operating air pressure.
