Arduino people?

[matt167]

Anyone good with arduino? My father in law is a butcher with a smoke house and he wants to introduce water to create steam and raise the humidity for a couple products. He needs specific humidity levels. I know arduino can operate solenoids based on inputs and this should work but I have only a small amount of project knowledge on arduino. I have programmed some small stuff. A digital readout of the actual humidity would be helpful as well. But I don’t know if the sensors output a voltage like a temp gauge or if it’s a special digital value.. also his smoke house runs up to 210*F so sensors need to be able to handle that temperature

 

[cdabc123]

Use something like a fuel injector. Presurize the water abit and send it pulses based on the sensor value and desired output.

There are sensors that would work but that's the hardest part of the project. Any sensor could be used with a arduino with relitive ease. You will probrably need to impliment some software to smooth and make since of the sensor output. Although with good clean sensor data you could just do a limit switch based on the desired output like a old ac.

 

[matt167]

I was just thinking a relay with a 120v solenoid that can control a water flow. He has actual spray nozzles for this use. But he lacks a controller. Adding the full shebang to his smoke house is quite a chunk of money to essentially buy the kit that is available . His main thing is getting 95% humidity to make hot dogs

Basically spray water until the target humidity is sensed by the sensor and shut it down

 

[blackmomba]

I had a project using a raspberry pi and some temp, humidity and moisture sensors as well as a few water pumps.

Temp and humidity are straight forward to wire up and python libraries are available and easy to use. My problem with this was accuracy but I was using cheap stuff from Amazon

For The moisture sensors, I needed an additional chip for analog to digital conversions. I think I used another python lib for this and the chip I needed was pretty common and easy to find

For the pumps I didn't get messy with relays or anything, I found a 110v power strip that could be wired up to the pi, you could toggle outlets off and on which is where I plugged the pumps

Changes in the environment would trigger the pumps on and off

 

[toast0]

I think your desired temperature and humidity range is going to make finding sensors tricky. I've got some homemade temperature and humidity things which could have been Arduino, with an ESP8266 and a DHT11, but the DHT11 temp and humidity sensor's published range is: Temperature Range: 0°C to 50°C, Humidity Range: 20% to 90%. Not sure what else is out there though.

Arduino is fairly simple if you've done any C++ and have experience smooshing together open libraries. Basically, install the board library, then a library for your sensor (probably available), read the sensor in Arduino's loop() function, and poke at the output pin that allows the water in. If you're a regular developer and hate how non-transparent the Arduinon IDE is, try platform.io ... For me, it feels less magical and makes it easier to understand more of what's actually going on.

You might look into irrigation valves, which usually run around 24v ac? You would need a relay for that and an appropriate supply of course.

 

[michalrz]

One way you can make it cost-effective is to not use an Arduino development board for the final product.

I'm all gung-ho for the tiny85/84 microcontroller, you can get those for like a dollar.
The 85 is a tiny 8-pin IC, you can connect a cheap OLED display for digital readouts (0,96" is like $3), which still leaves 3 free pins for reading analog signals/turning stuff on/off. There are also cheap break-out boards for it that expose pins and provide basic circuitry.

You can upload code to the 85 using an Arduino as a programmer.

The sensor is the real problem. The DHT11 might die after a while of being exposed to smoke.
I'm thinking something like a higher voltage (12?) applied to a piece of sponge and try to measure the mV in the microcontroller (through a /2 voltage divider, the 85's input accepts 5V).

 

[matt167]

A wet and dry bulb sensor system is the normal way the commercial units do it. There is a chart so it should be able to range both sensors together. An arduino is $20 so it won’t break the bank. Adding a full system commercially made is in the thousands

 

[matt167]

I found temperature probes good to 257*F so i should be able to use it than statements to compare

 

[michalrz]

I found temperature probes good to 257*F so i should be able to use it than statements to compare

I've found that a good starting point for any project like this is figuring out the rate at which you need stuff to happen.
For example, you don't want to poll sensors too often.

This step also helps you avoid using delay(), which is a major source of headaches down the road.

The FireTimer library is a very easy and clean way to do it.
Take a look at the code example over at https://github.com/PowerBroker2/FireTimer , you might find it to be a good starting point for any program. I'm recommending this as a starting point because that's how I like to do it, it's not obligatory.

 

[cdabc123]

I've found that a good starting point for any project like this is figuring out the rate at which you need stuff to happen.
For example, you don't want to poll sensors too often.

This step also helps you avoid using delay(), which is a major source of headaches down the road.

The FireTimer library is a very easy and clean way to do it.
Take a look at the code example over at https://github.com/PowerBroker2/FireTimer , you might find it to be a good starting point for any program. I'm recommending this as a starting point because that's how I like to do it, it's not obligatory.

This is a decent point. Many simple arduino programs rely on delays but the second you need much else from the device it becomes a huge pain. That's half the reason I enjoy using fpgas for my projects.

 

[matt167]

These are good suggestions. I have not had much success with delay. I’ve had it crash my arduino before

 

[matt167]

Will DS18B20 probes work under these harsh conditions? The way it works is one with a wet sock over the probe that wicks water out of a water source and a dry one measuring dry air. Comparing the 2 readings difference calculates the humidity

 

[michalrz]

Will DS18B20 probes work under these harsh conditions? The way it works is one with a wet sock over the probe that wicks water out of a water source and a dry one measuring dry air. Comparing the 2 readings difference calculates the humidity

I think they would work, it's just a TO-92 packaged part, and as long as you prevent the pins from shorting out, it should be okay.
Datasheet says they can use parasitic power (no dedicated vcc line) up to 100 deg. C.

Another thing I remembered, aside from the temperature and humidity, the presence of solenoids/relays might cause Arduino/sensor instability. But you can work around that with a capacitor in parallel and antiparallel diodes across the relays.

Disclaimer: I haven't played with those sensors.

 

[cdabc123]

Is this a closed space where you can just use water volume boiled to know humidity?

Maybe water volume introduced and airflow of exhaust would be enough to infer humidity.

I'm not sure those sensors would work as the base sensor is at a far different temp and air quality from the humidity sensor.

Either way I think it's worth logging data from the sensor as a experiment first so you know what you have to do regarding data processing and calibration as I dont think it will line up with the library base calibration for many of these sensors.

 

[matt167]

Is this a closed space where you can just use water volume boiled to know humidity?

Maybe water volume introduced and airflow of exhaust would be enough to infer humidity.

I'm not sure those sensors would work as the base sensor is at a far different temp and air quality from the humidity sensor.

Either way I think it's worth logging data from the sensor as a experiment first so you know what you have to do regarding data processing and calibration as I dont think it will line up with the library base calibration for many of these sensors.

I’m not sure. He just knows that commercial units use the wet sock dry sensor system. But the controller alone is in the thousands. I’m going to mess with them to figure out their accuracy and create offsets if needed. He had an automated smokehouse at the USDA plant that he sold so he is familiar with the hardware

 

[michalrz]

In that case, definitely start off with just placing the sensors in various locations and just observe their ins and outs, like cdabc123 suggested.

An ESP32 or ESP8266 is an "arduino with wi-fi", almost a drop-in replacement in many cases. You program it in the Arduino IDE, typically using the same libraries.
It would help you track the readout - you could use your phone or PC instead of having to babysit it.

 

[matt167]

I think something like a humidifier in a box could be used with a hair drier or heat gun. It could easily bring the temp up that high. I could have it activate a buzzer once its up to humidity