Phidget and Artisan and Gas and Air Pressures

Discuss roast levels and profiles for espresso, equipment for roasting coffee.

#1: Post by SJM »

I'm using the Phiget 1048 ( to read the three t/cs on my HUKY.

Is anyone here using Phidget 1136 ( to record air flow?
I'm assuming I can run both the 1048 and the 1136 through a 1018( ?

Can anyone corroborate this for me?

Is there a Phidget that can record the very low gas pressures???

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#2: Post by cannonfodder »

The warning would worry me. You may want to make sure your gas supply would work with the sensor via Phidget before you try it.

This sensor is designed to measure the pressure of clean, non-condensing air. Contact with moist air (i.e, human breath), dusty air, or other gases can damage the sensor.
Dave Stephens


#3: Post by SJM »

Good point. I of course had paid no attention at all to that.
The airflow I was considering measuring would most definitely not be clean.

I guess that puts paid to that idea;
and I guess that's exactly why I asked.


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#4: Post by ira »

A MAF sensor from a car might work. they can probably stand air up to 150F or so. Make sure you get one with analog out. You'll need to provide a 5V or 12V supply and you'll have no idea what the output means, but in my experience they are quite repeatable and if you have a pick-your-part, probably not very expensive. I'd probably start with one off a 2000-2008 Ford. They are normally held in with a couple of Torx screws making them easy to mount into something else. I've never run hot air through one, well, not much over 100F.


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#5: Post by ira »

Or stick a fan with a permanent magnet dc motor in there and measure the generated voltage.

Or attach a stick with a vane and a spring or small weight to a potentiometer and measure the resistance.

I think you'll find any of those will repeat close enough for roasting. They will give you no idea of actual airflow, but should give you everything you need to roast consistently.



#6: Post by SJM »

Too complicated.
I'm still thinking I can make the Phidget module work, but that I will have to do it carefully and thoughtfully.
If the Phidget route doesn't work I will stick with calibrating my variac with an anemometer and doing my best guessing...:-))

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#7: Post by MaKoMo »

I installed a Phidgets 1136 last summer to measure airflow in my Probat LG3 on the exhaust. That setup still works as expected and I got informed that at least two others followed me and got this working as well on larger machines. I know that Morten in Denmark uses that same sensor, but is measuring the pressure in the roasting drum with similar results.

The main problem is that this sensor is not able to stand the high temperatures of the coffee roasting air. The trick is to connect the sensor not directly, but via some small brass tube and a short flexible tube connector. That way, the temperature of the air pressure at the sensor location is within its normal operating conditions. Further, I pointed the brass tube in direction of the airflow, measuring negative pressure (relative to the second pressure input of that differential sensor that I left alone at ambient pressure. That way I avoid that this measuring tube gets clogged by chaff or other particles in the exhaust air. Note that you need to ensure to properly bend that tube and not to fold it. I used a specific bending tool (see the pics below).

That Phidgets 1136 can be connected to Artisan via the general IO Phidgets 1018 or an SBC or any other Phigets IO component supporting analog inputs.

Hope that the pictures below give you an idea of that setup,

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#8: Post by hankua »

Thanks for posting this Marco!
Just in case anyone wants to go analogue, it would work with a Dwyer Magnehelic 2000 series gauge. The three that would most likely fit are the 20001 0-1.0 wc, 2000-0 0-0.5 wc, and 2000-00 0-0.25 wc. I see the 0-1.0 wc installed on the SF75 and 0-0.5 wc worked on the Mini500.

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#9: Post by MaKoMo »

The advantage of going digital is that you can log the airflow along the temperatures. Here the light blue line shows the airflow (air pressure) as measured by the Phidgets sensor on my Probat 3Kg. You see how it changes with different damper settings or drum/fan speed (one motor) settings. Damper and motor speed are also recorded automatically here using some MODBUS frequency drive and a variable resistor.

The grey "air" signal is the quantified (using the quantifier mechanism in Artisan) air flow derived from the light blue airflow signal. To keep the profiles readable, I usually hide the raw airflow signal and only visualize that quantified signal indicating the changes in the airflow.



#10: Post by SJM »

The copper tubing looks to be 1/4"?
And are these two parts common hardware store (plumbing department) fittings?