CIP device for espresso machine portafilters

[Mark Kelly]

Thought you might find this entertaining.

I cobbled this together out of a few stainless fittings and a double acting air cylinder. The male bayonet fitting takes the place of the spout on the portafilter (they're a standard 3/8 BSP thread). The corresponding female connects to the stroke supply port of the cylinder. The return supply port is plugged:

Bits

Place a spoon of sodium percarbonate (or your cleaner of choice) in the portafilter, attach it to the machine as normal:

PF Mounted

Attach the cylinder via the bayonet:

Cylinder attached

Run the machine forward, the hot water runs through the portafilter, dissolving the percarbonate and the solution is forced into the cylinder, forcing the piston out:

Up

The air pressure in the return side rises as the cylinder moves due to the blocked port. When the machine is stopped this forces the solution back through the portafilter return loop, cleaning out the gunk in its path. No pic since this looks exactly like pic 3 anyway.

Rinse and repeat. Actually works best if you detach the cylinder before rinsing as the void volume in a standard portafilter is about 50 ml so it works best if this is emptied. Reattach the cylinder and run a cycle on plain water and you are done.

The fittings cost me about $AUD30 (roughly $USD20) and I have several spare cylinders from my frame fatigue tester building exercise, but if you need to buy one they're about $AUD50. I used a 50mm bore x 80 mm stroke which gives a swept volume around 150 ml. I don't use all the swept volume: I don't want to compress past 90% as in theory the temperature rise would exceed the safe operating temperature of the seals. In practice the cylinder sinks the heat quite adequately as far as I can tell.

There is a very satisfying rush of light tan foam when the pressure is released, and of course this also cleans the drip tray. I might try to do a video of this in action.

[crankles]

Love it!

[darkmother]

I don't own an espresso machine-but this is pretty cool^

Why sodium percarbonate? (I ask because I don't know).

[Mark Kelly]

Sodium percarbonate is an excellent all purpose cleaner / sanitiser that isn't hard on surfaces such as aluminium. It isn't a single compound, it's actually a 3:2 solid solution of hydrogen peroxide in sodium carbonate. Once in solution the carbonate pulls the pH up to 10 or so which makes the peroxide more effective.

Many of the expensive commercial coffee machine cleaners are based on it. I always have a 25 kg sack of it on hand in the winery (see above re all purpose sanitiser) so I pay about $3 / kg rather than $20.

[tanghy]

can you make me one?

[Mark Kelly]

No, and I don't need to. The bits are available on Ebay or from any industrial supplier and they simply screw together.

Just be aware that coffee machines use the international thread standard (ISO / BSP) while the USA has its own "standard" (NPT), which is used nowhere else.
I used a 50mm bore x 80mm stroke cylinder with a 1/4 BSP female thead.

The female coupling is a standard air coupling with 1/4 BSP male thread. As long as these two match, the actual thread doesn't matter so you could use 1/4 NPT for each and it will work*.

The male coupling is a standard air coupling with a 3/8 BSP male thread. The elbow is a dual 3/8 BSP female elbow. You could use a 3/8 NPT coupling and a 3/8 BSP to 3/8 NPT female elbow but that fitting will be harder to find.





*Although the two standards are close enough to work in some sizes (eg 1/2 and 3/4, the common garden tap sizes) they are not interchangeable in the sizes I'm using (1/4 and 3/8) as the thread counts differ: NPT is 18 TPI and BSP is 19 TPI. Where this gets crazy is in some of the large sizes where BSP set the standard at 11 TPI and NPT decided on 11 1/2 TPI. Yep, a fractional thread pitch. GO Team USA.