The Lelit Bianca uses a flow control valve and some people add the Lelit flow control valve to an existing machine. Many owners assume is maintenance free, it’s not and without maintenance can cause problems as the O rings inside the valve degrade. These apparently fit the coffee sensor version as well…see end of post.

reduced flow
difficulty in controlling
no flow
leaking at the top of the valve spindle

Fortunately, the valve is easy to maintain and problems are easy to fix. The following 2 videos show the internals of the valve and how it works, plus the installation process.

The original O rings are EDPM and sized as follows…I think FKM (Viton) is better, comes in green or black colours and interestingly ECM use FKM on their valve.

EDPM or FKM (I think might be better) size 6.07 × 1.78

My recommendation would be these…but the company does EDPM as well. certainly in hotter HX machines, I would choose Viton

https://simplybearings.co.uk/shop/p512590/BS010-1.78mm-Section-6.07mm-Bore-VITON-Rubber-O-Rings/product_info.html

Maintenance

These systems are not maintenance free and often it will depend on usage. From the factory, I think the valve manufacturers use insufficient lube, so this might be something you wish to check. I lubricate the O Rings with Molykote 111, as I believe it is the finest all round lubricant for espresso machines, but must always be applied to a totally dry surface. It’s fine for Viton (FKM), or EDPM, but should not be used on Silicon seals as it causes them to swell.

Maintenance should be every 3-6 months depending on usage and would involve removing the valve as lubricating the parts described in the first video, remember, it must be completely dry. It’s important to avoid moving the valve until the machine is hot, to prolong its life.

Eventually the O rings will degrade, and then it’s time to pop replacements in. If you bought a bag of 50 O rings (£9.29 delivered!), you can change them annually for less than 40p per year….you will be good for the next 25 years 🙂

If you have an ECM valve split it and do the same…I think the ECM o rings are the same size, but I forgot to check with them when I was over there.

Apparentl; these fit the coffee sensor flow device as well.

Some BS010 Viton O-rings, from the FAQ on Lelit’s Flow Control Valve (thanks DavecUK ) - they seem to be the correct size for Coffee Sensor’s flow control device as well (the green O-rings in the picture are the ones that came with the the Coffee Sensor device. The blacks are new).

Comments from one of our members @Doram after changing the O rings in the coffee sensor flow valve above.

I just pulled the first shot after servicing the flow control device and replacing the O-rings and I was completely shocked by the result. Not only was the action of the valve so much smoother, I was actually able to control the flow completely, stop it, hold the pressure where I want it and get instant reaction from the manometer - all things that I was NEVER able to achieve before!

Until today, when I tried to almost close the device for pre-infusion a few seconds after lifting the lever, I could slow the ramp up a little, but that was about it. Then when I would tale off the pressure to end a shot, there was a delay in reaction and I would usually go down to about 6 bar to end the shot. I saw videos of people holding pressure for long periods (at 2-4 bar for example). In those videos, manometer reacted instantly to closing/opening of the valve. Mine didn’t do that, and I just assumed that my machine/flow control device are ‘different’. What a fool I was! I now realise that when I first got the device I damaged the O-rings by opening the valve too much. The valve probably never sealed completely since then, so I was only able to make small changes to the flow, but not control it completely. With the new O-rings and some lube, I finally get to play with the flow control device as it should be (I hope I am not getting carried away here - this was just one shot and I still have to play and confirm the above, but couldn’t resist sharing already). For anyone who is as stupid as me, your FAQ is priceless.

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