Anyone here have experience with this kind of direct mount pressure transducer?

[rshortt]

From ebay:

http://www.ebay.ca/itm/Pressure-Tra...Fuel-Air-Water-/322488964981?var=511464069357

I'm looking to automate my electric brew rig using a raspberry pi and expanding on Craft Beer Pi.

Does anyone here have experience with this kind of pressure sensor? If so, what are the pros and cons?

Cheers, and thanks.

 

[BrunDog]

5 psi is a water column of ~140 inches of water. So unless your kettle is over 10 feet tall, you will not get the resolution needed. Less than 1 psi is needed depending on the max height of the wort in your kettle you will be measuring. Stainless direct contact sensors do exist for this pressure range but are pricey. Another user and I will be testing some custom made ones - will report back. I have had success with non-direct contact sensors using an air-gap method, so no bubblers are needed.

 

[rshortt]

Thanks. I've also read your threads and posts on the topic so thanks for that too.

I was searching for a 1 or 2 psi version of this since I was wondering about the psi range in question.

So these things don't measure from 0-5 psi? If not, what is the range?

 

[BrunDog]

Your linked sensor might measure 0-5 psi but to generate 5 psi of pressure your kettle (or tank or whatever) would need to have 140 inches of liquid - not typical on the homebrew scale. My 15 gal kettles are 18" high, and I might fill them 15 inches max, which is only 0.55 psi. So if you use a sensor with 10x the range, you will lose essentially that much resolution.

One other FYI for your RPi solution is you will need an analog to digital converter, as the RPi cannot natively measure analog signals.

 

[rshortt]

Makes sense regarding the range.

Roger that on the analog sensors - I'm planning for that. I'm also using PT100 temp probes and have some MAX31865 amplifiers on the way. I may make a little pi shield incorporating these, analog to digital converter, relays, etc.

The first step for me in automation is getting my kettle filled though. I'm eBIAB now but moving to a 2 vessel HERMS.

 

[jangevaa]

I just bought a pressure transmitter through aliexpress, and 0-6kpa was the most appropriate range for me (roughly 24 inwc).

Many of the pressure transmitters meant for higher temp applications will have a heatsink/heat fins of some kind I've noticed. I'm surprised this one, just by looking at the design, has as high as a working temperature as it lists.

check out hoprodgarage for some inspiration - he has been detailing his build with pressure sensors, he posts on here as well but the instagram is great: https://www.instagram.com/hoprodgarage/

I'm planning on writing a CraftBeerPi plugin for 4-20ma inputs (using some TBD ADC, these are nice and affordable though! https://widgetlords.com/blogs/pi-spi-series)

 

[rshortt]

Thanks for the info, jangevaa. Do you have a link to the aliexpress unit?

Edit: Like this?