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Big project question - salami drying room

  1. Jan 16, 2009 #1
    Okay I'm pretty new to all this and this is my first post on this board.

    I graduated last year from university with a cellular biology degree, and have now taken over my family's italian food business (est. 1968 by my grandfather). We produce both fresh and dry-cured meat products.

    What I want to do is make a salami drying room. I have already used some information from this site regarding relays and temp controllers to start a portion of the project. There are ultra sophisticated systems that can be purchased from Italian companies.

    What these try to accomplish are all of the following:
    1. Control humidity with a microprocessor that "ramps" the %rh down from (for example) 100% to 60% during the course of drying. The reason for this is so the salami doesn't dry too quickly at the beginning causing the outer portion to form a crust, sealing the inner portion and reducing further drying.
    2. Control temperature with a microprocessor, similar to the humidity ramping.
    3. Keeps air flowing throughout the room by using diffused air ventilation.

    The only problem is that each of these rooms costs about $100 000, and we need three.

    What I have done that seems to be working quite well is to buy a standard desiccant dehumidifier, and connect this to a Love Controls humidity controller. I am now ramping the humidity and temperature down manually. What I would like to do is use an Arduino board to control a relay that will switch on and off the dehumidifier. In this way I can automate the process.

    The problem I am having isn't with the code, but with the idea of controlling a 110V dehumidifier with the arduino....the physical aspect of the whole thing. Is it even possible?

    Okay that was an extremely long explanation for a small question...but there will be many more questions on this thread and I'd like to offer some sort of reward to people who help me with this...since it is for my business.
  2. jcsd
  3. Jan 16, 2009 #2


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    Sounds doable in principle--the Love Controls unit just drives an 8A relay. I doubt that you can control the relay directly off of the Arduino (you probably need a transistor or few to be able to drive the coil). The makers of that unit also seem to manufacture humidity sensors / humidity transmitters that you could interface with the Arduino.
  4. Jan 16, 2009 #3


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    What you are looking for is very similar to how pharmacuetical companies do stability testing. I've worked with many types of chambers and rooms where both temperature and humidity are controlled. In some of our chambers there were controllers that could be programmed to ramp up or down for a number of different profiles. I remember one that might be of interest to you. Maybe you could contact them and see if they could supply you with a controller.
    Also you might be able to find used environmental rooms and equipment.

    Welcome to PF
  5. Jan 16, 2009 #4


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    Those Thermotron chambers are not designed to accommodate fresh air flow as per the OP
  6. Jan 16, 2009 #5


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    I was talking about the controllers not the chamber itself.
  7. Jan 16, 2009 #6


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    Yes, sorry, I missed that.
  8. Jan 16, 2009 #7
    Almost every environmental chamber I have worked with (20+) have used Watlow controllers.


    The nicer ones are programmable for ramping/soaking schedules and include all the PID controls and stuff. You could still do all the same things with the Audrino but it will probably cost about the same in the long run after you add a display, interface, relay drivers, power supply, etc while requiring a lot more time.
  9. Jan 16, 2009 #8


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    Thanks Topher. Yes Watlow is what was on most of our chambers and rooms. I didn't realize they made controllers that did ramp and soak profiles.
  10. Jan 16, 2009 #9
    dlgoff, Topher925, mheslep, MATLABdude

    Thank you all for your help. i am going to research every one of those options. That is basically what I was looking for, but couldn't find anything on my own.

    Do you guys mind if I stick around the forums and ask for help if I need it, or if I have some hobby projects I'm working on?
  11. Jan 16, 2009 #10


    with the watlow controllers, I would just use one of the temperature controllers modified for humidity, or this one here (http://www.instrumart.com/Product.aspx?ProductID=23665)?

    do they have specific humidity controllers?

    EDIT: this one does humidity...nm http://www.instrumart.com/Product.aspx?ProductID=20340
  12. Jan 17, 2009 #11


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    The environmental rooms I've been involved with needed both a cooling and a heating source. Depending on the temperature need ususlly the cooling would not be controlled and the Watlow would control the heater. For relative humidity, the cooling source would tend to dry the air and the other Watlow would control a steam generator to add humidty to get the desired value. The inputs to the controllers in our case was a thermocouple for the temperature and a humidity sensor/transmitter (typically a 4-20ma output type). There are several sources for these humidity transmitters depending on accuracy you need. Here are a couple:
  13. Jan 17, 2009 #12
    The F4D is a very poplar controller and should work well for your application. Before you pic a specific controller, determine what equipment you will be using for humidity and temperature conditioning.

    Some humidifiers do not operate by measuring humidity directly, but by controlling the dew point temperature of the humidifier (water bottle). If you know the temp of the air in the cabinet and you know what you want your RH to be, you (or the controller) can easily determine what temp to set the humidifier bottle at with a little bit of psychrometry knowledge.

    You will also need a heating system, this is usually done with electrical heating coils which can be easily fabricated. You will want a thermocouple or RTD for this as well to prevent over heating via an alarm on the watlow.

    Depending on what temps your using, you may not need a cooling system. Instead you can just blow ambient air into the chamber.
  14. Jan 21, 2009 #13
    It is going to be mostly dehumidification I think...the salami in its raw form adds lots of humidity to the room, which needs to be removed. Any suggestions for off the shelf desiccant dehumidifier suppliers?

    I'll have to post what I did afterwards...maybe other people can make italian cured meats too.

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