Bluetooth Pressure Gauge for the Sage/Breville Barista Express.

[xandmann]

UPDATE:

Just got delivery from the Fab. House and DigiKey.
Will assemble the module this weekend, than "fine-tune" the firmware and we should be in business.

The iOS App is ready, will be sent in to Apple for review the coming weekend.

[xandmann]

UPDATE:

Still waiting for my PCBs, seems they got stuck in Swedish customs. But the iPhone App is coming along nicely.

[Jackster]

That is true mr.Jack.

The guy is obviously a brainiac. I looked through his post web page and instagram. Pity he has no article about the bleed valve on his bz99. Would love to learn more on this subject

[MrJack]

Ok. Bypasses around pump. Its a poor replacement for a opv. Imo.
If your grinds determine a 12 bar extraction and your valve is adjusted to 'dumping pressure' to 10bar, then you are dumping 20%. Midway through the extraction, when the pump could be delivering 10bar, you are still bypassing 20%, so delivering only 8bar to the puck.
Even in the link if you check the pics the poster was unhappy with the arrangement and was trying to mechanise the tap operation. It looks like he gave up on that as well and was going to try something else.

Maybe the bypass in conjunction with a solenoid to shut the bypass when pressure drops. But a opv isnt that expensive or hard to set up.

Sorry to divege from the op topic.
Looking forward to seeing this work out as a cool project

I assure you, the poster is still using the setup. Whilst not perfect, it's far superior to an OPV, which is a poor replacement for a control valve (and is still fitted to the machine BTW).

You can't adjust the flowrate mid-shot with an OPV...

[Jackster]

Ok. Bypasses around pump. Its a poor replacement for a opv. Imo.
If your grinds determine a 12 bar extraction and your valve is adjusted to 'dumping pressure' to 10bar, then you are dumping 20%. Midway through the extraction, when the pump could be delivering 10bar, you are still bypassing 20%, so delivering only 8bar to the puck.
Even in the link if you check the pics the poster was unhappy with the arrangement and was trying to mechanise the tap operation. It looks like he gave up on that as well and was going to try something else.

Maybe the bypass in conjunction with a solenoid to shut the bypass when pressure drops. But a opv isnt that expensive or hard to set up.

Sorry to divege from the op topic.
Looking forward to seeing this work out as a cool project

[MrJack]

A inline restrictor in the brew path doesnt sound like a good idea. You may as well have a double wall basket. Probably a double wall basket would be a better restriction
Or is the restrictor going as a bleed screw and dumping off pressure where a opv would go?

It is upstream of the basket (in fact, in my case its on a bypass line around the pump). No coffee passes through it, not comparable to a double wall basket at all.

Also, you can't "dump pressure" - you can divert flow though

[xandmann]

UPDATE:

The first batch of components have arrived for the project. Also got word from the FAB house that the PCB:s are manufactured and sent.
Done with the firmware for the BLE112 module, and the first version of the iOS App for iPhone.

Actually I will be testing several alternatives for temperature measurements. The module will have both analog and I2C inputs.

LM35DT
MLX90614
TC74

Below the "cheaper, no name" ±1.5% FS accuracy Pressure Sensor, have also ordered a Honeywell PX3.

[Jackster]

A inline restrictor in the brew path doesnt sound like a good idea. You may as well have a double wall basket. Probably a double wall basket would be a better restriction
Or is the restrictor going as a bleed screw and dumping off pressure where a opv would go?

[MrJack]

If you don't mind a bit of manual tweaking, there are easier (and cheaper) ways to control brew pressure than via pump speed adjustment:
https://www.instagram.com/p/BKInEJFB6WP/

[xandmann]

Yes, you get brew pressure on the gauge. But it is only regulated by the grinds. If its like the 6910 and 6900 i think it will just stall out at max pump pressure. There is a bypass thing on the output of the pump, but on inspection its a vacuum breaker, not a pressure relief.
So a opv will regulate pressure at its setting, and then drop as the puck wets out.
Without the opv, its only the resistance of the puck regulating the pressure. Even if you know the pressure, you cannot change it other than by the grind.

You could set up pressure profiling though...use the pressure gauge to regulate the pump. Maybe pid the pump?

Maybe, but for that I really need to take the machine apart to see what is possible to do.

[xandmann]

Done with the first revision of the PCB for the sensor module. Will send it to the fab. house next week.
Pretty happy with the size 30 x 45 mm so it fits perfectly in a Hammond 1551 plastic enclosure.

[Jackster]

Yes, you get brew pressure on the gauge. But it is only regulated by the grinds. If its like the 6910 and 6900 i think it will just stall out at max pump pressure. There is a bypass thing on the output of the pump, but on inspection its a vacuum breaker, not a pressure relief.
So a opv will regulate pressure at its setting, and then drop as the puck wets out.
Without the opv, its only the resistance of the puck regulating the pressure. Even if you know the pressure, you cannot change it other than by the grind.

You could set up pressure profiling though...use the pressure gauge to regulate the pump. Maybe pid the pump?

[xandmann]

The pump over pressure valve in this machine only operates as a safety valve (opens at a set point to prevent pump or machine damage) rather than a traditional OPV (opens at a set point to regulate pressure within a set range).

There is no benefit in knowing the pump pressure in this machine. You could install an OPV from a Breville Dual Boiler but this won't make a whole lot of difference to the in-cup taste. I've tried it before and it's not worth the effort for such little result.

It's a cool project though and certainly could be of benefit in other machines in the future.

Well, there is a pressure gauge on this machine, the outlet for this gauge sits on the top of the group head.
Correct me if I'm wrong but my understanding is that by digitising that pressure one would get the actual "brew" pressure ?

[noidle22]

The pump over pressure valve in this machine only operates as a safety valve (opens at a set point to prevent pump or machine damage) rather than a traditional OPV (opens at a set point to regulate pressure within a set range).

There is no benefit in knowing the pump pressure in this machine. You could install an OPV from a Breville Dual Boiler but this won't make a whole lot of difference to the in-cup taste. I've tried it before and it's not worth the effort for such little result.

It's a cool project though and certainly could be of benefit in other machines in the future.

[xandmann]

Under the hood in the Barista Express... (before the modification)