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Vaccum Controls

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Plumr
Plumr Member Posts: 3
in THE MAIN WALL
Has anybody worked on any industrial control systems that use pneumatic stats? why do they use air instead of electronics? where does the air come from?

Plumr

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  • BillW@honeywell
    BillW@honeywell Member Posts: 1,099
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    Pneumatic stats

    In the late 1800's, buildings were getting too large for individual stoves and fireplaces to heat. Steam was used as central heating, but the results were poor because no real controls other than manually adjustable valves existed.

    Most buildings had pneumatic messaging tubes that were used to pass documents from floor to floor in special cartridges that were filled with papers, put into an air lock, then "shot" to their destinations, just like the containers used in some bank drivein tellers today. Electricity didn't exist, so they needed a power source to operate auotmatic valves, so they chose to tap into the compressed air supply.

    The mothers of all steam-powered air compressors lurked in the basements of these buildings, so air was not a problem.

    Pneumatic stats work by using the temperature caused flexing of a bi-metal element to allow more or less air to escape from a tiny orifice in the stat. This in turn builds up or releases pressure in the diaphragm of a valve or damper actuator(motor) opening or closing the valve or damper in proportion to the amount of pressure in the line, and in response to temperature changes. A spring assists the main air pressure in opening or closing the valve or damper, and establishes its position (normally open or normally closed). Pneumatic actuators are extremely powerful, and can handle monster valves that no electric motor can. Main air pressure is usually around 25 psi, provided by a compressor and filtered and dried before it goes out into the system.
  • [Deleted User]
    [Deleted User] Posts: 0
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    Hey Bill

    The first subway in NYC was driven that way. It was put in in secret and was powered by a BIG steam powered fan. Check it out!

    http://members.tripod.com/~earthdude1/subway/subway.html

    Noel
  • BillW@honeywell
    BillW@honeywell Member Posts: 1,099
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    first subway

    Yes, that was some subway system! Those old compressors that ran some of the pneumatic messaging systems were incredible contraptions of gears, pistons, flyball governors, huge flywheels and drip lubricators. Some were powered from a another steam engine by a big leather belt. The receiver tanks were riveted, and the saftey valves were weighted levers. YIKES!
  • Kritz_3
    Kritz_3 Member Posts: 85
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    Steam driven air compressor

    Here is a nice old compressor at Kings County Hospital in Brooklyn NY. I am told that this bad boy still can blow some air!! Although not in use now it was kept around because the chief of engineering has a warm place in his heart for things of steam.
  • Kritz_3
    Kritz_3 Member Posts: 85
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    Steam Air Compressor

    Here are a few pictures of a steam driven air compressor at Kings County Hospital in Brooklyn NY. I am told that this old beast can still blow some air. Enjoy the pics.
    Kritz
  • BillW@honeywell
    BillW@honeywell Member Posts: 1,099
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    Thank you!

    That old iron is really amazing. This is what real machinery looks like, purely mechanical. Thanks for the info. Noel, stop drooling!
  • [Deleted User]
    [Deleted User] Posts: 0
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    Oh, Please

    Can I come clean it and paint it?




    Can I have it? They won't miss it.....

    Noel
  • Kritz_3
    Kritz_3 Member Posts: 85
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    Steam Envy

    I asked FIRST!!!
    Nice stuff, just needs some TLC.

    Steve
  • BillW@honeywell
    BillW@honeywell Member Posts: 1,099
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    My sentiments ,exactly!

    I was thinking a nice shiny black or red paint job with some gold pinstriping on the flywheel rims and spokes. I really do need to get a life!
  • Kritz_3
    Kritz_3 Member Posts: 85
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    All steamed up

    And properly shining brass name plate!!
  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928
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    Looks like just the thing...

    ...that "Punkin Chuckers" would love to have for their air cannons.

    If you haven't seen it on the Discovery Channel watch for it--about the most bizarre grouping of improvising rednecks I've ever seen. Considering where I'm from, that's a BIG statement!
  • BillW@honeywell
    BillW@honeywell Member Posts: 1,099
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    Punkin Chunkin

    Southern NJ and Delaware are centers of this phenomenon. Last year they had several hundred entrants, and it made national TV. My favorites were some engineering students who built a Roman catapult AND appeared in full Roman soldier get-up. Another group of looney-bin escapees built a medieval trebuchet as their entry. Both flung pumpkins great distances, but I don't know who won!
  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928
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    2002 fest in DE

    Is where the Discovery Channel episode was filmed.

    Multiple categories:

    Human powered--generally the catapults and Trebuches(sp) in the 1,000-2,000 ft range.

    Mechanically powered--generally truly wild centrifugal machines, 2,000 - 2,500 ft or so.

    Air cannons--think a WW-II German "super gun" coming out of an old school bus--3,000 - 4,500 ft!

    There may have been more but I was too busy laughing at one guy starting his OLD truck with enough ether to set the engine compartment abaze!

    All 8-10# pumpkins and the object is NOT to make "pie."
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