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  • Exploding coffee machine

    While Ive had a stove top explode on me when the safety valve blocked, this one is a bit scarey...
    http://www.dailymail.co.uk/news/article-1311946/Sainsburys-coffee-explosion-injures-7-caf.html
    (especially looking at the first photo - looks like the boiler unravelled itself with the output of a large amount of energy )

    What could cause that? Is a domestic machine likely to do something similar?

  • #2
    Re: Exploding coffee machine

    Originally posted by 735553414E730E200 link=1284516145/0#0 date=1284516145
    What could cause that?
    Probably a faulty pressure relieve valve on the boiler but possibly a lover of good coffee, in which case theres little chance theyll be sabotaging your domestic machine.
    Especially as youre a Coffee Snob; your coffee is of a higher standard.

    Comment


    • #3
      Re: Exploding coffee machine

      Any machine with a boiler can do this.
      Mythbusters had a show where hot water systems blow up and act like a rocket.

      Two things need to happen.
      The safety pressure valve is blocked and the temperature control (pressurestat on a coffee machine) is hard on.

      Comment


      • #4
        Re: Exploding coffee machine

        Not Unravell - but has suffered what appears to be some less than desirable effects.

        That being said, better to have it split at an early stage than to let go at an even later stage.  High pressure boilers are dangerous and Coffee machine boilers are not in the same class.

        What I thought interesting, was the 3 elements and the way they are sitting  

        Then again, without the hands on and closer inspections any one of 101 reasons might have caused this...  

        However, one would have assumed a WORKING safety valve would / should have preventive this level / type of uncontrolled pressure release.  And then the heating would also need to be active as well.

        Thus at least TWO faults at the same time and no one noticing; the off coffee  AND OR the gauges AND OR the steam performance..

        The fault would not have happened in seconds... But taken a little time to build to the level it did 

        Comment


        • #5
          Re: Exploding coffee machine

          Originally posted by 7E7D6F6F6B7D651C0 link=1284516145/2#2 date=1284518626
          Any machine with a boiler can do this.
          Mythbusters had a show where hot water systems blow up and act like a rocket.

          Two things need to happen.
          The safety pressure valve is blocked and the temperature control (pressurestat on a coffee machine) is hard on.
          I saw the myth busters show. And I saw first hand what a safety valve failure does with a stovetop coffee pot - it looked like a small scale version of the mythbusters experiment with the pot making a rapid departure from the stove . It was a stainless steel pot and examination of the debris indicated corrosion around the weld at the base of the water container , which then failed spectacularly leading to rocket power across the kitchen. So it also needed a double failure as the safety valve failed to go off.

          Comment


          • #6
            Re: Exploding coffee machine

            Originally posted by 7576646460766E170 link=1284516145/2#2 date=1284518626
            The safety pressure valve is blocked and the temperature control (pressurestat on a coffee machine) is hard on
            Agree.

            Originally posted by 56797072655A76797670727A727963170 link=1284516145/3#3 date=1284518638
            OR the gauges
            I wondered why no one noticed the guages too... but I guess in a busy or quiet shop it could slip past the users.

            You can see it does have a pressure valve (red circle in the pic) and I know I test mine once a year with a firm tap with a spoon to make sure that it works and that it re-seats ok. I guess it could go pear-shaped between tests though.

            I can only guess they didnt make much coffee in the hour before, the pressure would have been high enough to just blast steam and water through the group and a volumetric pour would have taken seconds.

            Spooky and strange at the same time.


            Comment


            • #7
              Re: Exploding coffee machine

              Very astute and insightful as always, Andy.

              Note that the force was directed out the back of the machine which is what propelled it forward and out towards the consumers area. The bowing out of the face plate reflects the internal forces direction, and look at how the majority of the force was directed out the back.

              This was an extraordinary event, to be sure.  To have the pressurestat stuck closed AND the safety valve not open would point me towards scale buildup as the first factor I would look into as it could cause both.

              In hindsight, if the machine were fastened securely to the counter or wall, it might not have been launched, but this is such a rare event that except for seeing this we would never have thought of taking such safety measures.

              A person standing in front of that machine when it launched could easily have been killed.

              I like the "spoon" test, Andy. I think it should be added to descale instructions.

              Comment


              • #8
                Re: Exploding coffee machine

                Originally posted by 5D6E616B765048210F0 link=1284516145/6#6 date=1284523356
                Note that the force was directed out the back of the machine which is what propelled it forward and out towards the consumers area. The bowing out of the face plate reflects the internal forces direction, and look at how the majority of the force was directed out the back.
                Uuuummmm......Just as a rocket moves in the direction opposite of the direction of its exhaust so would this machine move in the direction opposite to the direction of the jet/explosion of steam. With the boiler blowing out the side opposite the brewing heads the machine would have been launched towards the brewing side/barista, not towards the customers. Only in the case of the barista being on the same side as the customers (i.e. The machine was placed against a wall.) or a ricochet would the machine have launched towards the customers. More likely the customers were injured by debris blown off the machine, not the machine itself.


                Java "Gotta love physics" phile
                Toys! I must have new toys!!!

                Comment


                • #9
                  Re: Exploding coffee machine

                  Originally posted by 4C677067766E6F6A63060 link=1284516145/7#7 date=1284525796
                  Uuuummmm......Just as a rocket moves in the direction opposite of the direction of its exhaust so would this machine move in the direction opposite to the direction of the jet/explosion of steam. With the boiler blowing out the side opposite the brewing heads the machine would have been launched towards the brewing side/barista, not towards the customers.
                  I must have misread something. I thought I read that the machine ended up out on the floor of the customer area... Whoops... :-[

                  Action and equal reaction... Gotta love that newton fellow, that and his fig cookies. ;D

                  Comment


                  • #10
                    Re: Exploding coffee machine

                    Originally posted by 42717E74694F573E100 link=1284516145/8#8 date=1284529425
                    Action and equal reaction
                    3rd Law of Motion.

                    Originally posted by 42717E74694F573E100 link=1284516145/8#8 date=1284529425
                    his fig cookies
                    1st Law - a body at rest (eating fig newtons) will remain at rest unless acted upon by another force (the wife).

                    Comment


                    • #11
                      Re: Exploding coffee machine

                      Cause of Sainsburys coffee machine explosion revealed

                      "The environmental health officer (EHO), technical representatives from the machine supplier, independent forensic engineers and Sainsburys in-house engineering team have been investigating since Tuesday and have identified the cause of the problem," the spokeswoman said.

                      "The supplier of the machines has confirmed that in 2009 a design amendment was made to the machine that could potentially allow this type of failure, and that the original design of equipment could not fail in the same way.
                      Anybody out there with an Elektra might want to check with the manufacturer and see if their machine incorporated this design amendment.


                      Java "No more BANGs please!" phile
                      Toys! I must have new toys!!!

                      Comment


                      • #12
                        Re: Exploding coffee machine

                        Good time to do a descale.

                        Comment


                        • #13
                          Re: Exploding coffee machine

                          Originally posted by 7D564156475F5E5B52370 link=1284516145/10#10 date=1284628432
                          Cause of Sainsburys coffee machine explosion revealed

                          "The environmental health officer (EHO), technical representatives from the machine supplier, independent forensic engineers and Sainsburys in-house engineering team have been investigating since Tuesday and have identified the cause of the problem," the spokeswoman said.

                          "The supplier of the machines has confirmed that in 2009 a design amendment was made to the machine that could potentially allow this type of failure, and that the original design of equipment could not fail in the same way.
                          Anybody out there with an Elektra might want to check with the manufacturer and see if their machine incorporated this design amendment.


                          Java "No more BANGs please!" phile
                          Want to bet on how long it takes them to go back to the old design?

                          Greg

                          Comment


                          • #14
                            Re: Exploding coffee machine

                            Originally posted by 003522201028352A262B23470 link=1284516145/12#12 date=1284633078
                            "The supplier of the machines has confirmed that in 2009 a design amendment was made to the machine that could potentially allow this type of failure, and that the original design of equipment could not fail in the same way.
                            Yea so what was the detail... This just sounds a little like some minor mumbo jumbo to me..

                            If it is true then one might expect a large number of recalls...

                            OR

                            There will be the added bit where it will take x and y to happen and where the USER does not take some action...

                            Thus an updated amendment to the user manual and or a warning sticker  and they will be covered.

                            [edit]A Sainsburys spokeswoman said the incident happened when the "boiler" within the coffee machine failed due to over-pressurisation.

                            It was caused by a failure of the pressure relief valve to operate, she added.[/edit]


                            From a Quality view; that is not the root cause, its just one symptom and they have not delved deep enough OR willing to go public


                            It is still only ONE issue.. Excess heat and other things had to happen OR not happen at the same time :

                            Comment


                            • #15
                              Re: Exploding coffee machine

                              From reading other reports on the explosion it appears the machine was situated against an exterior wall. Some articles state a hole was blown in the exterior wall of the store with the homeowner next door stating that debris hit their house.

                              For all owners of such machines: If its not already on the list you should add the pressure relief valve to your checklist of items to regularly check to verify proper functioning.

                              Originally posted by 5E71787A6D527E717E787A727A716B1F0 link=1284516145/13#13 date=1284633924
                              From a Quality view;that is not the root cause, its just one symptom and they have not delved deep enough OR willing to go public
                              I suspect the latter as what theyre doing now appears to be purely brand/company damage control and reassuring the public. Anybody with technical knowledge of these types of machines knows this accident involved multiple system/part failures. Not just a failure of the pressure relief valve.


                              Java "Its all about public image dont ya know!" phile
                              Toys! I must have new toys!!!

                              Comment

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