I have been on a wonderful espresso journey, starting from a Breville Barista Express, then Niche Zero, and now I've decided to do a lot of learning by building my own custom mods on a GCP. I have plenty of skills on the software side, and some of the electronics side, so this will be a long and fun project for me. I am fully aware I could simply go and get me a Decent or the newly planned meticulous, but I think I will learn more this way and maybe discover something someone else hasn't =).

I would appreciate suggestions for what kind of food safe pressure transducer to use on the pressurized side of a GCP (thinking right after, not sure if to do this *after* the boiler though; I imagine the necessary transducer becomes even more specialized to sustain the higher temperatures). I am posting this with full awareness of Adding flow and pressure sensors to Gaggia Classic Pro and will refer to it below.

I have read with interest the Gagguino project where they suggest https://www.aliexpress.us/item/22558005 ... _shipto=US as a solution. The component uses 304 steel housing and the pressure sensor is ceramic based, which is somewhat reassuring, but it doesn't specifically list food safe as an attribute for the component.

Then I saw in the thread referred to in the first paragraph the reference to Huba 501, and took a look at the specs

https://pdf.directindustry.com/pdf/huba ... open949757

and started to research the materials that are in contact with the thing being sensed. BTW, I found the Huba 501 spec sheet more informative and trust inspiring than the spec I could find for the lower cost transducer component suggested by Gagguino.

Still, when I researched 303 steel I found:

https://stainlesssteelfoil.com/products ... l%20grades.

Which left me scratching my head. Then I started researching sensata sensors, and I found 127CP, which is a "food safe" version

https://www.sensata.com/sites/default/f ... asheet.pdf

This was a nice development - finally someone specifically stating the words "food safe" in a product, although I couldn't find how one could procure a sample of that 127CP.

At any rate, I am a bit lost. I figured one safe way to go is to find out what pressure transducers reputable espresso machine manufacturers use, or ask this question in this forum.

I appreciate your remarks in advance!!

Thanks, yes, I've been looking in websites and it doesn't seem like they carry the 126CP/127CP.

Even the sensata website itself lists part numbers for the 116 series, but when you write 126 or 127, it gives you 116 parts. I suspect this is a "call me" situation. Which I could do, but I was hoping that in this forum someone could point to a part that is being used by a reputable machine.

Additional comments:

In the ito kit,

https://www.softwareandcircuits.com/div ... ure-v2.php

the following transducer is suggested:

https://www.newark.com/honeywell/px3an2 ... p/10AC4428

However, the documentation (https://www.farnell.com/datasheets/2569677.pdf) states:

The PX3 Series is not recommended for use with media involving water, saturated air such as steam and vapor, and ammonia.

Bottom line, I am still looking for a choice of pressure transducer that I have some evidence is safe to use for an espresso machine setting.

There's things like this, but the aren't cheap.

https://www.ato.com/high-temperature-pressure-sensor

Try searching for "USDA pressure sensor steam"

Mostly anything that search returns should be safe.

The ato sensor looks impressive design-wise. It also seems to be aimed at much more difficult environments (1000 bar!!). It may be food safe (they do list medical applications) although I couldn't find specific standards that they have passed.

Does anybody know of pressure transducers that are used in espresso machines? I did find

https://www.specialistespresso.com/prod ... mbly-eltek

but no specs on it.

Thanks for the tip on searching for USDA.

Of course. I figured USDA would get food safe things. But anything that's all stainless with a welded stainless diaphragm is likely to be food safe even if it doesn't say so. I'm sure a phone call would confirm that. They come in all sorts of pressures from a few bar to way to many. Took me a few tries during which I some over $1000 before I found that one that seemed pretty reasonable. There were certainly lots to choose from. I have some high vacuum valves that have welded stainless bellows where there is no path between the inside and outside so It can't leak when opened no matter what.

I'm curious what you ended up going with? I'm going down a similar journey as you - I'm very intrigued by the gaggiuino project, but I don't want non-food safe parts touching my coffee.