Calculating Humidity / insert new graph on HM homepage


 
O

Olli Bavaro

New member
Hello guys,
As suggested from Bryan I start a new thread about this topic =)

Thanks to the 4 possible probes on the HM I was experimenting with calculating the humidity inside my smoker. Easiest way is to use
a wet and dry bulb temperature. I transformed probe 4 into a wet bulb thermo using a cotton shoe lace. Now my question is, if it is
possible to do a real time calculation / graph of the humidity using these formulas. I'm no HTML pro so fiddling with the existing or copy & paste
is currently the maximum I can perform =(

http://easycalculation.com/weather/dewpoint-humidity-calculator.php

I found this temperature quiet interesting in estimating "the stall" and keeping the meet moist and juicy.

http://modernistcuisine.com/2012/08/barbecue-stall/

Bryan also stated:
"The value could be calculated in the HTML but the graph comes from the database, so that means the humidity would have to be calculated on the backend and the database would have to be modified to hold the value. You'd also need to know the pressure but it appears that you can just use a standard average and it doesn't affect the output too much."

I think since a smoker is not air tight the outside pressure would be sufficient. If you are living in Salt Lake City or high up in the Alps this could result in a
major error if we take just a mean value. Perhaps it needs to be possible to insert your height or outside pressure :D


Regards
Olli
 
I'm very interested in this concept, on account of
emot-science.gif
SCIENCE and all.

So you just take a piece of shoelace and put it around the Maverick probe, then put the end in a puddle of water? Doesn't the water evaporate quickly inside of the BBQ? I agree you can probably use just an average pressure for your location. This and a drop down selection for which probe is being used for the wet bulb would be all that is needed.

This is something that will have to wait for v12, because v11 is too close to release now, but I am interested in hearing more about any experimentation you've done already.
 
For the quick and dirty wet bulb thermometer I just used a thick sholace laying around. You will need to cut one end and then push in the probe step by step. The probe needs to be like 2-3 cm in.
After this I just taped it to a old coffee mug filled with water. The other end of the sholace needs to hit the water. Bulb at the probe needs to be wet to. You can check if everything is working
in your room. The wet bulb will be noticalbe cooler than the dry bulb. With this information and your static pressure you will get the humidity =)
Currently I'm searching for a big enough hx-diagram for water to quickly see what humidity is reached.

For the next weeks I'm planning to do some test runs on my WSM trying to keep the humidity up. I think creating a nice bark could be done in the last phases or with a little kiss with my torch.
 
I am actually quite interested in measuring the humidity in the smoker as well. I built a UDS that has a lower rack on which I have been placing a deflector pan filled with beer or water for each smoke. It greatly changes the "feel" of the smoke coming out of my smoker to be quite damp. I am able to get enough liquid in the deflector pan to last a majority of the smoke, even on larger briskets, and it doesn't seem to boil.

The interesting part is that a group of buddies and I all built our UDS about the same time earlier this year, but we all took slightly different (after opinionated debate) approaches. I was the only one with the deflector pan and beer setup, but several of the other guys are coming around because after each of us cooked our first few briskets mine were always generally moister. I am wondering what changes to the length and duration of the stall I am creating by actively raising the humidity in my smoker. I would suspect it makes the moisture on the meat evaporate less, or slower, delaying the start of the stall and the cooling effect of it, but conversely perhaps prolonging it. DFW is generally considered a drier climate, but having grown up in Colorado and visited New Mexico I realized its only dry relatively speaking to areas like Houston. To a degree local humidity and altitude could play into creating great bbq as well.

The simplest thing is to use a probe as the wet bulb temp, but it seems the setup could make it a bit error prone or user dependent. Browsing mouser, humidity sensor components are not that expensive, though its hard to tell if they would survive in a smoker and have the necessary temp range. Would it be possible to add/monitor one?
 
All the humidity sensors I've seen are rated for up to 85C, standard industrial temperature range. I doubt they'd survive the heat and more importantly I think the smoke would eventually destroy the sensor.
 
It doesn't say what you do with the number though.

No code changes are needed to put a wet wick over the probe. I'm done! :-D
 
Interesting discussion on maintaining humidity in a smoker. Bottom line:


  • Humidity matters.
  • It is REALLY HARD to maintain high humidity levels in an oven or smoker without extreme effort.
  • Most methods you read about on the web or in recipes are malarkey.
  • Water is very hard to convert into steam or vapor. It takes energy, time and surface area.
  • Since it is hard to measure humidity directly or inexpensively under cooking conditions, measure the water loss rate, and use that as a surrogate humidity level.
 
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