EVO2 Dumping Water

[Matt Waite]

Does anyone else use Braun's EVO2 machines?

If so, has anyone experienced them dumping water mid-disinfect?

This is a (very) long standing (yet unresolved issue) issue (which Braun are aware of), and I'd be interested to know if it is just us or a more widespread problem.

It only happens on our EVO2 machines (the original Evolution and V8 machines are somewhat different inside). The machine will randomly, intermittently but persistently dump around 60ml of diluted citric acid solution from the tank overflow. Usually this goes with air sculling around the upper levels of the machine and a drop in internal pressure on PDA. I have theorised that we're seeing boiling under reduced pressure and the extra volume of the 'steam' in the closed system is over filling the tank, but many hours of fault finding hasn't identified a cause.

The issue isn't always easy to spot as wet floors in the Unit are a slip hazard and are promptly cleaned, and a little fluid on the floor is far from unusual (as Hansens are coupled etc). The give away is the complaints from cleaning staff about the sticky residue left behind under the spare machines that don't get moved as much and those which auto on-and-off unattended.

This is not just one or two machines, its been most of them at one time or another, and they have done it since delivery. It smacks of a design 'feature' rather than a fault that we can pin down.

If this sounds familiar, do let us know.

[Garry]

We do see similar on occasions, not sure if the same issue as yours

Braun technical have said that some units see it and some don't so not sure the root cause is known.  My understanding is that water can track inside the upline tank from one of the water inlet pipes (from bicarb wand rinse assembly?) to the overflow under certain conditions.  A temporary fix was to reverse the pipe entrance points - so that the overflow is above the inlet causing the issue.  Not sure if this was official advice so maybe best to check.  

We have also noticed it, on occasion, when performing central thermal disinfections though, saying that, it has been a few months since the last incident as far as I am aware.  This is a particular issue as this type of disinfection usually occurs out of hours when equipment is unattended.

I think a design change was planned (may have happened already) for new equipment.

[Matt Waite]

Thanks for the reply.

I think you're describing something different. We've had that one too. We brought it to Braun's attention, only to be told it doesn't do that. Sending them a video of it happening managed to convince them!

The tank has been redesigned on later machines - the inlet is not longer directly over the overflow so any turbulence around the inlet can't cause water to find its way straight out the overflow anymore.

[Andy Mosson]

I was just about to make a post about this and notice Matt has already beaten me to it by a long way.
I am now refusing to put Dialog EVO's a home until the problem is resolved although it appears Braun have no intention of tackling it.
The problem is due to imbalance of the gear pumps. If FPE performance drops below FPA then more water is returned to the inlet tank and it overflows. Braun should try to resolve this as it is leading to pumps needing changing prematurely and I think it is a design fault which should be rectified. It never happened on earlier Dialogs.

Chris asked if Dialogs are good at home - apart from the above problem , yes! Dialog+ is extremely reliable and easy to service but a bit too heavy if stairs are involved.

Andy

[Matt Waite]

The solution for us was to replace the FPE pump. It fixed every machine with the symptom. The original pumps had roughly 6K hours on them.
 
Now we're 6K hours into the replacements we've had a small number (so far) of them fail with the same problem and they've had to be replaced again  

We heard verbally that  issue was possibly to do with the loading effect of the magnetic coupling pulling the carbon gears into the pump body causing premature wear, and were advised to reset the coupling to its 'neutral buoyancy' position when fitting replacements. We've had nothing in writing to this effect though.

[Andy Mosson]

To me it is not a surprise if pump performance changes over several thousand hours. I don't consider it is that the pumps are worn out but that the problem is having to change the pump prematurely because the Dialog design won't cope with the imbalance. It was not a problem on earlier Dialogs and Braun should instigate changes to make it less susceptible to this imbalance - certainly it should not overflow!