Sampling mechanism for humidity meter

I’m working on a grain humidity meter. So a couple of sensors sit in an Acrylic chamber with the mcu and battery pack in an adjacent chamber which is shown here in greyed out lines.

The two sensors (blue and fuscia) are shown inside the chamber and I’m thinking of simply adding a pullout latch (also of acrylic) with a stop at the end. The user would pour the grains into the chamber and push the latch back in and then take the measurements.

Any suggestions or ideas on how to improve it?
IMG_2375.jpg

Any suggestions or ideas on how to improve it?

Yes, put some labels on it.

like that?

I meant suggestions about the mechanism

Where is the hammer? What purpose does it serve? To crush the grains?

Why two sensors? What model of humidity sensors? How are they positioned inside the chamber and why?

It might be quite a few minutes before the humidity level inside the closed chamber stabilises. Was this device designed to take measurements quickly?

Sorry, the autocorrect changed chamber to hammer. There is no hammer.

It's for taking quick measurements. The sensing part is taken care of. At present I'm trying to figure out a way to get the grains in and out of the acrylic chamber which is roughly 2" x 2" x 6" tall.

Marciokoko:
It's for taking quick measurements. The sensing part is taken care of. At present I'm trying to figure out a way to get the grains in and out of the acrylic chamber which is roughly 2" x 2" x 6" tall.

Electronic humidity measurement is generally slow.
How fast do you intend this to take.

Given the size of your container it may tell you if the grain is wet but not give you a useful indication of the water content of the grain over a short timescale.

Marciokoko:
At present I'm trying to figure out a way to get the grains in and out of the acrylic chamber which is roughly 2" x 2" x 6" tall.

Why not copy the mechanical design of existing commercial grain humidity sensors?

I am not sure if humidity sensors are used for this.
I suspect it may be a resistance measurement.

Hi,
Do you want the moisture content of the grain, or the humidity of the air around the the grain.

If the latter you will need a very longtime for any moisture to evaporate out of the grain to humidify the air, and you need to know the moisture content of the air before you placed the sample in the chamber.

google measuring grain moisture content

Tom... :slight_smile:

Sorry wrong thread

oh, i thought you were being sarcastic. LOL

Current devices on the market use a screw cap which is cumbersome when sampling many times. It might be better but im looking for a tradeoff. Im looking for a quick and dirty way to sample and I want to compare what the losses are in accuracy or precision vs a market device.

They all measure the moisture content of the air around the grain, at least the field devices. Otherwise one would have to grind the sample first which would make the device more complex. More sophisticated devices do measure moisture content of the grains by cooking them and measuring the weight differential but those are lab devices.

Marciokoko:
. Im looking for a quick and dirty way to sample

That may me difficult.
Tom George has made some valid observations.

From experience my hand held humidity meter needs at least 1/2 hour to give a stable reading.

That also depends on how it is stored.
A large change in humidity means it takes longer to reach a stable reading.

Ultra fast sensors exist which respond in a few seconds but i do not know where / how much they can be found.

Marciokoko:
At present I'm trying to figure out a way to get the grains in and out of the acrylic chamber which is roughly 2" x 2" x 6" tall.

Turn it over ?

Is this for some sort of repetitive or automated test ?