Help Please: Problem with espresso basket and pressure

fmarshall

New member
Oct 30, 2018
1
0
From some observation of a Krups XP5280, it appears that the espresso basket retains pressure during the brewing process. And, it appears that it retains some water/brew after the process ends.
Now, of course, "espresso" means that the brew is expressed from the ground beans under pressure. So, the basket being pressurized during brewing seems just right.
With this XP5280, I've been having the situation where the brewing process yields no output. Instead, in time, the machine stops - my notion is that it stops due to excess pressure / force on the pump piston.
I believe that I've proven to myself that the baskets are somehow malfunctioning and cause the pressure to build up. Indeed, if I stop the pump, the basket can retain a fairly high pressure even if there is no ground coffee in it! And, this pressure remains in the basket for some time - unlike a normal brewing cycle. In a normal brewing cycle, the basket comes off easily and doesn't try to push itself off when unlocked. In this case, there is horizontal pressure on the handle when it's unlocked.

I've dismantled and cleaned the baskets to the best of my ability. I've soaked them in vinegar for a day and used hot water and compressed air to clean them out.

I'm very curious to understand how these baskets are designed to work. I have two theories:
1) The basket includes a pressure relief valve that regulates the pressure. That would account for some water being left behind.
2) The basket includes a small outlet orifice that limits outflow and, thus, allows pressure to build up during the brew cycle but not thereafter. That would also account for some water being left behind.

There are two places that I can't easily examine:
There is a feed tube that goes from the upper basket (holding the ground coffee) to the lower part of the basket. Light doesn't readily pass through this tube. Is there a check valve in there?
There is a small rubber diaphragm with a tiny hole in the center that fits into the bottom of the upper basket. It looks like it could be important. But having it clean doesn't assure proper operation.

Another theory could be that the pump is weak and won't produce adequate pressure for an assumed pressure relief valve to work. But this doesn't account for the retained pressure in the baskets.
Some baskets work more reliably than others. An old basket works better than a new one.

Does anyone know how these work?
Is there a particular part that's critical to it working? Yes, sure. But where?
Any suggestions?
 

Musicphan

Active member
May 11, 2014
1,516
6
Kansas City
I have no working knowledge of that machine but it does sound like you have a problem with your pressure release valve. Typically you would have a relief valve within your machine and not within the basket - but again I have no knowledge of your machine. I would be careful not to get your machine pressurized to the point your pump is weak - that may cause additional problems burning out the pump. Have you tried Krups yet? Have you cleaned / backflushed your machine (if recommended by manf)
 
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