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<controlling fire extinguisher with a servo> :frown:

  1. Jun 24, 2011 #1
    <controlling fire extinguisher with a servo> plz help :frown:

    Hi,
    I am building a robot that can extinguish a fire on it's own with the help of a couple of sensors and a fire extinguisher.
    I want to control the lever of the extinguisher autonomously with the help of the http://rcelectro.com/index.php?page...category_id=4&option=com_virtuemart&Itemid=4" . The robot will be equipped with a fire extinguisher. the robot is operated by 2*60 rpm (12 V) motors. so, the structure of the robot should be able to hold the weight of the extinguisher.
    Which type of fire extinguisher should I use? and what should be it's weight and the most imp can this servo be used to trigger the extinguisher?
    What will be the mechanism? I am thinking of a pulley type( please see the doc attached.)
    I think i am wrong so plz can any1 suggest me a solution for this
    THankx in advance :D :D
    Regards,
    Shubham
     

    Attached Files:

    Last edited by a moderator: Apr 26, 2017
  2. jcsd
  3. Jun 24, 2011 #2
    Re: <controlling fire extinguisher with a servo> plz help :frown:

    Are you trying to control the flow coming out of the fire extinguisher? If so, you could use a solenoid valve to control it.
     
  4. Jun 24, 2011 #3

    berkeman

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    Re: <controlling fire extinguisher with a servo> plz help :frown:

    Speaking as a person who has a fair amount of fire extinguisher training (and having put out a few real-world fires with them), you don't modulate the handle. You squeeze it fully when you deploy the extinguisher. You can modulate it on-off-on-off every couple of seconds, depending on what the (small) fire is doing, but you don't use a half-on type squeeze for anything.

    So, the best actuator would be a solenoid that you activate to fully squeeze the handle. I'd recommend using a 5-pound or 10-pound "ABC" fire extinguisher for your project, since those are the most common types that are used in buisinesses and homes.

    I'm assuming that this is a school project, and not a real commercial application, right? There is a lot more that goes into fighting a fire than rolling a robot up to it and firing an extinguisher at it.
     
    Last edited by a moderator: Apr 26, 2017
  5. Jun 25, 2011 #4
    Re: <controlling fire extinguisher with a servo> plz help :frown:

    @berkeman
    You are right this is for a project.
    I dind't understood how to use a solenoid. Are you suggesting that instead of a valve, extinguisher should be equipped with a electric solenoid actuator ?
    well, if so
    one of the major dis-advantage of a solenoid actuator is that they produce small force, so only operate in small valves

    Regards
    Shubham
     
  6. Jun 25, 2011 #5

    berkeman

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    Re: <controlling fire extinguisher with a servo> plz help :frown:

    I guess you could retrofit an extinguisher with a controlled valve and have it recharged, but that seems like a lot of work. Plus, the extinguisher material gums up valves pretty well, so most household extinguishers are single-use only.

    I was thinking that a strong enough solenoid could be used to squeeze the handle, but perhaps you're right. The handle is pretty easy to squeeze, but the throw is several cm, which is long for standard size solenoids.
     
  7. Jun 25, 2011 #6
    Re: <controlling fire extinguisher with a servo> plz help :frown:

    I will be using this fire extinguisher.http://www.ceasefire.in/pdf/c789bcea-dfd9-476c-bacc-fd8b00a5e059.pdf" [Broken] Can it be retrofitted with a solenoid ?. will the valve able to withstand the pressure?
    I can ask the company to do it.
     
    Last edited by a moderator: May 5, 2017
  8. Jun 25, 2011 #7

    berkeman

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    Re: <controlling fire extinguisher with a servo> plz help :frown:

    What is your control algorithm going to be like? Is it going to be a single fire? Or would you want to incorporate several extinguisher shots as part of the effort? What are your overall project objectives, and how do you plan to address them at the low level (robot movement, extinguisher operation, etc.)? Honestly, with a 5 pounder, you have maybe 20 seconds, and with a 10 pounder, about 40 seconds of flow (ballpark).

    If your strategic plan is to use a single fire, just use a small solenoid to pull a pin from under a big enough spring to compress the handle. If you want multiple extinguisher actuations (and if you do, why?), you will need to use a big enough solenoid with a big enough throw or leverage to depress the handle on demand, IMO.
     
    Last edited by a moderator: May 5, 2017
  9. Jun 26, 2011 #8
    Re: <controlling fire extinguisher with a servo> plz help :frown:

    I think I will incorporate several extinguisher shots .

    I am making a fire fighter robot.
    the extinguisher will be mounted at the top.
    robot will move with the help of 2 60 RPM 12V DC motor and 5 wheels.
    the extinguisher now will most probably operated by a solenoid valve.( I have a company that if they can do it.)

    Well, the extinguisher is only one but the shots fired are not
     
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