If you haven’t heard this story yet click here first (new window).
Thankfully there were no fatalities or serious injuries sustained. Bloody lucky really judging by the mess of the boiler….. If you’re not sure how an espresso machine boiler works I’ll briefly explain. The boiler is1/2 to 3/4 full of water. This water is then heated with an element. Unlike many other “heating” systems an espresso machines element is controlled by a pressure switch not a thermostat. That is to say that the element heats the water until the water heats and generates steam. The steam is trapped inside the boiler and the water keeps being heated and the pressure raised and becomes a pressure vessel. The water will be over 130 degrees C in a pressurised state. (Just like your grandmothers pressure cooker!) When the machine reaches a certain pressure. (just above 1b) the element cuts out. Once the pressure drops (I.e. the release of pressure via a steam wand, or the introduction of cold water from the auto fill system) the element is switched back in to bring the pressure back up. What happens then if the pressure switch fails? Well either it will stop the element switching in or LEAVE it switched IN. In this case the element will heat the water and the pressure will continue to build until something gives. If the machine has been maintained then the safety pressure valve should operate and release the pressure. If not it will be the next weakest thing point. Probably a leaky gasket. The pressure will just make the hole bigger and it will go bang!
The one question that has echoed around the coffee forums and Twitter today is this: ” Why didn’t the pressure release valve operate?”
Good question! The reason for having your espresso machine serviced every year isn’t to make your espresso taste lovely or so your friendly neighbourhood coffee company can rip you off. It’s to keep the thing safe and in good working condition. It checks pretty much every working part, replaces any that are faulty and highlights any potentially faults. It renews all the important seals (of which there are many)and de scales the machine where appropriate. Safety mechanisms are tested; primarily the pressure safety/over pressure valve. Not only will this ensure the machine is safe but it keeps the most important tool of your business running smoothly! The last thing you want is an important part like the pump/pumphead (a good example of failing part an engineer can spot really early on) to fail at 8am on a Saturday! Not only would it mean business downtime it will cost double to get an engineer out over the weekend/if at all!
Unfortunately it’s all to common for operators not to bother and avoid the cost. They just keep on going until something lets them down. Not only does this cost more in the long run but they are really putting themselves at risk! In my time as an espresso machine engineer I’ve lost count of the times I’ve found a machine an a total state due to lack of regular servicing and on several occasions I’ve come up against a stuck fast pressure safety valve. It’s only a tensioned spring and a plastic seal and needs to be maintained.
Certified Pressure Safety Valve - My valve of choice!
If you are an owner of a coffee business then you may have heard of a Pressure Vessel certificate. To my knowledge (so I’m probably wrong here) it’s not illegal to operate a machine [within a business premises] without one. (although your insurance company may need one to issue cover***) However, it is law that your pressure vessel/namely your espresso machine receive a regular/yearly service and should be policed by your local EHO. It’s a subject that as a machine engineer I have done much research into. HSE guidelines are pretty vague at present. It’s pretty confusing as to who can actually issue a certificate in the first place. The guidelines say “A competent person” but then fails to elaborate on what passes for competent!$$$
You can bet that after this latest incident that local authorities will get pretty damn twitchy and the guidelines will have to be made clearer. I’m hoping that it will also make operators think about their own machines. For some reason operators see a service with suspicion. I’ve had it put to me that the service is there just to make money. Several customers have had a first service for years because the EHO happened to ask about their service record. One customer said that he avoids them because the last one he a repair it caused loads of problems a week later. Well, yes possibly. If you haven’t had a service in years then there is of course any work might cause another problem. One good example is the pump head. A failing one will show up way before is dies completely, but will struggle on for an age & slowly get worse and the pressure getting lower. On a low use machine, a restaurant say, then it could even last a year or two. When your friendly engineer replaces this (usually because he wont pay for a service, just wants the problem fixed) all of a sudden you have the machine pumping 9bar and putting loads of stress on other parts. This is when old seals/gaskets start to fail. If this machine had recived a yearly service then the pump head fault would have been identified and replace WAY before it got too bad.
PLEASE PLEASE PLEASE get your machine serviced every year, possibly even more under really heavy use. You can bet your life that the EHO will come knocking very soon asking about your service record!
$$$ If you have any more info on this please feel free to comment and correct me and I’ll edit the post. Are you a distributor, engineer or operator? Get in touch below and share your thoughts. What impact has this had on your business?
***One of my customers had this problem. The insurance company insisted that an HSE inspector (an EX naval steam engineer) inspect the boiler. Unfortunately for my customer the inspector insisted that the boiler be removed and stripped prior to inspection. This meant that I had to remove the machine to my workshop then MY WORK I WAS TO BE INSPECTED to ensure that I put it back together properly and installed the pressure safety valve correctly! That was a fun day!!!!