stanley_c_wong Senior Member Joined: 23 Oct 2006 Posts: 62 Location: Singapore Expertise: I love coffee
Espresso: Silvia, Krups 5020 Grinder: Rocky
Posted Mon Jan 7, 2013, 1:52am Subject: Exploding Portafilter
I have had an Expobar Office for the past 2-3 years. I bought it second-hand, but it looks to be in good condition.
There were no incidents in the first year. Then, one day, the portafilter simply exploded out from the grouphead. It was bad. I had Bodum glasses below and I cut my hand in some places. Thank God, none of the cuts were serious enough to require stitches.
I was leery about using the machine after that and I made sure I firmly lock the the portafilter each time, and NEVER use Bodum glasses below (thoguh I might transfer the shot into one later).
Nothing happened. Then about 9 months later, it happened again. Luckily, the cups did not break (Pyrex!).
First time: Grind: Decaf coffee, bought in ground form, slightly larger grain than for an espresso machine. Tamp: Erhm, yes, I think I might have over filled it. Lock portfilter: normal Brew: 2 cup standard.
Second time: Grind: I do not remember, but I think it was espresso grind from my grinder (it was in the morning, and I only take decaf in the night). Tamp: I do not remember over filling. Lock: since the first time, I have made sure that I lock it with force each use. Brew: 2 cup standard.
I did examine the portafilter and I did see some wear, but nothing serious.
Pourista Senior Member Joined: 20 Dec 2012 Posts: 15 Location: Davis, CA Expertise: I live coffee
Espresso: Mishka's Medium Roast
Posted Mon Jan 7, 2013, 2:31pm Subject: Re: Exploding Portafilter
I had one explode on me in front of some customers once. I think the feeling of shock was equivalent on both our faces. It's a good thing you weren't seriously cut or burned! After it happened to me I always made sure to tighten to the point that others couldn't get it off (which was probably unnecessary). I know that for our machine at work, when we get it calibrated and have our tech replace gaskets ect...the portafilters always twist in less than they did prior to the upgrade. That shows there is wear on the parts and over time they get looser and looser (like a pair of jeans). If your portafilter has shot out twice now, I would look at the gasket it fits into and see if there is any part in there you can replace. Maybe it requires more torque to lock in place than 9 months ago? I'm not an expert on your machine or any for that matter, but it doesn't hurt to check. Maybe grinds are getting into the cracks and not allowing a complete lock?
alanfrew Senior Member Joined: 19 Dec 2001 Posts: 596 Location: Melbourne Expertise: Professional
Posted Mon Jan 7, 2013, 2:43pm Subject: Re: Exploding Portafilter
The portafilter "lock-in" on any machine relies on friction and pressure between the basket rim and the group gasket. Old group gaskets which harden to the point of polished ceramic are the main cause of this problem.
Did you change your gasket the first time this happened? Have you changed it since?
You SHOULD be changing out the gasket every 6 months or so, particularly if your machine is on most of the day.
stanley_c_wong Senior Member Joined: 23 Oct 2006 Posts: 62 Location: Singapore Expertise: I love coffee
Espresso: Silvia, Krups 5020 Grinder: Rocky
Posted Mon Jan 7, 2013, 6:32pm Subject: Re: Exploding Portafilter
Thank you Alan and Pourista for the advice.
Next time I do a thorough cleaning, I will check the gasket in the grouphead.
More information: This machine is for home use. I pull 2-8 shots 4-7 days in the week. The machine is on about 30min when I use it. I use both fresh espresso grind from a grinder and ground coffee, I think meant for filter coffee. Not heavy use when compared to a cafe, but significant I think. I will check if the gasket needs changing, and if there is a spare available in Singapore.
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