Vent ball design and operation

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Postby Terry_Pepper » Wed Jan 25, 2006 8:21 pm

As a result of a post made by BOATS in one of the other boards, I thought I would post the following section of a USLHE drawing of a standard vent ball used in 4th, 5th & 6th order lanterns.

As you will see, the vent ball assembly consisted of four main components, as follows:

1) The inner chimney.
2) The ball itself, with a series of holes around the lower edge.
3) A brass lightning rod
4) a 5 1/2" platinum point.

In operation, air passes up the chimney, and down inside the ball to the holes along the lower edge, and thence to the atmosphere.

The combination of the upper opening of the chimney being considerably higher than the holes, and the holes being at the lower (narrower) edge of the ball, created a watertight assembly, while still allowing a good airflow.


As an interesting footnote, platinum was used for the tip of the lightning rod because it served as an excellent electrical conductor, and was not destroyed when it took a lightning hit as brass would have been. At the time 19th century lighthouse engineers specified the material, it was not particularly expensive. Over subsequent years, platinum became increasingly expensive, and many a rod tip was removed by less than ethical Coasties during the 1950’s and 60’s, to be sold to precious metal dealers.
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Postby beachbum1616 » Wed Jan 25, 2006 8:43 pm

Excellent :!: I saw something somewhere recently that explained that the vent ball was just that, a vent ball, which for some reason, I didn't already know, nor did I really give it much thought.

Thanks for passing this along and I plan to watch this thread to see what more I can learn from it!

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Postby Hersh » Wed Jan 25, 2006 10:25 pm

Great info Terry, is there anything about lighthouses you don't have in your library?
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Postby boats » Thu Jan 26, 2006 1:43 am

Terry, you open the door for me on this one, Thank You. That drawing is all I need to make the ball work on the 30 foot light. :D "Boats"
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Postby mikev » Thu Jan 26, 2006 7:28 am

Careful, Boats. As some of us restoring non-working lighthouses have discovered to our chagrin, the holes also make old vent balls into excellent birdhouses or beehives.

Reminds me of the time we had an absolutely jam-packed tower and a line waiting to get in, and the volunteer at the top decided, for reasons known only to him, that the best way to inform me of a problem without panicking the crowd was to lean over the gallery railing and, drawing on his time in Germany, yell down "wir haben ein fledermaus!" Luckily, the bat was flushed out without chaos on the stairs.
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