RapidCoffee wrote:I tested this phenomenon in my review of the DE1.

johnnylarue wrote:Interesting question. The DE1 would definitely make a great educational tool, though it would kind of be like learning how to count on a graphing calculator. Anyway, the official literature on the DE1 cites a range of "0 to 9.5 bar". I don't have one so I can't verify this first-hand, but I would assume those numbers to be correct.

Stavey wrote:I've had my DE1+ for a couple of months and I have to say it insane what you can do with this thing . Honestly I think a better question is what can't it do. I think the only thing that can't be adjusted is pressure over 11/12 bar . This is to prevent damage to the machine. Aside from that everything can be adjusted.

DamianWarS wrote:from what I understand coffee can be classified as a non-Newtonian fluid which can have the properties of a solid the more pressure is applied.

decent_espresso wrote:Maximum requested pressure on all DE1 models is 12 bar.

Flow profiling is allowed to drive pressure up to about 13.5 bar, and then we back off on the flow.

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We leak test every machine at 19 bar of pressure for two minutes.

You will not damage the machine at high in the 15 bar range. Besides, the only likely "damage" would be a temporary water leak around a silicone o-ring seal. All components can survive extended periods at 19 bar.



I agree. Maximum flow vs pressure is attained around 8.6 bar, which coincidentally is more-or-less what "9 bar" machines actually deliver.

Yes, those early Italian espresso inventors who figured this stuff out were quite clever.

At around 10.5 bar the coffee puck compresses quickly again, and increasing pressure beyond 10.5 bar results in rapidly diminishing flow. Hoffmann challenged me years ago on this, and I thought it was both counterintuitive and unlikely. I asked the Decent community to do the research, and it turns out I was wrong, and Hoffmann was right.

I haven't found a useful coffee reason to go beyond 10.5 bar, and in a future firmware version we'll enable flow profiles to define their own pressure ceiling.

-john

decent_espresso wrote: In a future firmware version we'll enable flow profiles to define their own pressure ceiling.

-john