Why pressure relief valves should be checked & serviced

beanflying

Not a fan of the little CEME/Mater ones and they are known to fail more often, microswitches or small contacts like in them do fail open or closed. I did mean generally the larger ones used in commercial machines which are a very different device. Also a thought with the increased use of PID's programming safeties into them in case of Thermocouple failure.

FreshCoffee2

Still talking commercial amchines here. The manufacturer is never going to tell anybody nuttin about the real reason behind the failures, and it could have been as simple as a faulty batch of Boiler Safety Valves (that would not open if a pressurestat failed and continued to power the elements) delivered by the manufacturer of the valves. On machines where the pressurestat has never failed in that way, you would never know about a faulty boiler safety valve.... OR, there could be some kind of mechanical design change in the machine that stops the "flow' of pressure to the safety valve so that in the event that a pressurestat fails, effectively there is no safety valve present. I would think this would be extrememly unlikely given the safety valve screws directly into the top of the boiler, but you never know your luck in a big country. Some machines in the past have also had resettable (clickson type) thermostats fitted up against the boiler but they have their own little foibles. After that, its anybody's guess. The machine makes a great pirce of art that many modern artists could never hope to duplicate if they tried, and I especially like the elements fanning out at the top.

conikal

But surely there would be pressure tests and safety checks done an any new commercial machine before it is dispatched from the factory or passes off for use in a restaurant ! That would be like someone selling a new public transport bus and not checking the brakes work !

FreshCoffee2

Dont get me wrong, I am not going in to bat for these people. With any manufacturers I deal with, all machines are run & checked by a dedicated staff member that only does QA at the end of the production line before they are packed up. That is in the way they work, and electrically. But I dont know that they would deliberately overpressurise a boiler to see if the safety valve works. That would be the domain of the manufacturer of the safety valves before they are delivered to the esp machine manufacturer who in the case of something like the safety valve, is assekbling something that was made elsewhere. The manufacturers have various certifications for their boilers.....and if I remember rightly, I think (from memory) our manufacturer BFC also supplies the certificate for the safety valve as supplied by BFC's supplier/manufacturer..... I have no idea what these other people do.....but i dont think you can expect an esp machine manufacturer to test their machine in that way (to see if they can make the safety valve blow off)..... Would they also be expected to try and make the CPU fail to see if the fuses in the CPU will blow before irrepairable damage is done to the electronics? As to fitting more and more safety devices one after the other in case the immediately preceding one fails.....what happens when you fit 2 safety valves and they are both from the same batch which could be faulty? Fit 3 or 4 from different batches? Where do you stop/. I understand where you are coming from but as already stated (in a roundabout way) I think there is more to this instance than meets the eye. Hope that helps.

conikal

... I think there is more to this instance than meets the eye.

..agreed, ..Certainly more than we are aware of. But i am surprised that you would not expect a boiler safety to be checked after assembly ? Obviously you would not do any destructive type tests, but safety systems should (must ? for liability?) be checked on any new equipment after assy and during initial set up. Its not like a full boiler test,.. only 2 + bar and a pretty fundamental safety function. The valve manufacturer could not be held responsible for a wrongly installed valve. Its simple to test these valves ( on a domestic) using a bicycle pump via the steam wand. ( cold m/c obviously )

FreshCoffee2

Re: :"....Obviously you would not do any destructive type tests, but safety systems should..........be checked on any new equipment after assy and during initial set up...." Interesting point I'll put the question!

FreshCoffee2

FYI, the usual prompt and helpful reply from our manufacturer BFC in northern Italy: The Boiler Safety Valves used by BFC are tared and certified directly by their manufacturer and therefore they are not tested at assembly of the espresso machines. Additionally, BFC employs an independent lab that checks the components they use (all the components have to be certified). What anyone else does is.............? Hope that helps.

conikal

:🙂 Ha , i can just see those Italian hands waving, eyes rolling, and the shoulder shrugging...at the question ! 😃 :rofl: :rofl: You have to admire their approach to life. ! :thumb:

FreshCoffee2

I can tell you, BFC is much easier to deal with, more accommodating and transparent than the other.... ;D....in fact, than many others......

UNM

Is there any Australian requirement for boilers to be periodically pressure tested? I know gas cylinders need a test every few years. Just wondering.

FreshCoffee2

In terms of espresso machine boilers....not that I know of. Having said that, I dont know what it would prove because I dont think the boiler itself would ever be an issue. Also, just off the top of the head 😉 if you hydrostatically pressure test & measure the expansion of steel gas cylinders (to see if they remain within a certain range of expansion to either pass or fail), where the gas cylinders will return to their nominal size after the test (because of the elasticity of the steel), it may be a different kettle of fish to where you hydrostatically pressurise a copper boiler and it stays stretched and is therefore rendered useless for reassembly ie if you test it, you may actually be making it fail, ergo.....what for the test? And it may be that what you really want to test is the safety valve to see if it still works at its rated blow off pressure ??? OR.....at that point you may give up and decide its simply cheaper and quicker to replace the old safety valve with a new CERTIFIED rated safety valve, at pre determined iintervals during the working life of a coffee machine.

conikal

Fresh Coffee wrote:

.. it may be a different kettle of fish to where you hydrostatically pressurise a copper boiler and it stays stretched and is therefore rendered useless for reassembly ie if you test it, you may actually be making it fail,...

No, that would be testing it beyond its designed safe pressure.

Fresh Coffee wrote:

....at that point you may give up and decide its simply cheaper and quicker to replace the old safety valve with a new CERTIFIED rated safety valve, at pre determined iintervals during the working life of a coffee machine.

Assuming a functional relief valve makes the boiler itself safe is dangerous. What if the valve pot on the boiler gets plugged with scale ? Individual component checks do not ensure the safe function of the assembled system. To use the car analogy again,..its like the mechanic fitting new brake pads , and not road testing afterwards to ensure they work correctly. "Simpler" , "quicker", and "cheaper" are not words you would want to have to use in an accident investigation such as the one for this machine. I assume the installation /service technicians have a check sheet for start ups and service inspections that would be reviewed in this type of accident. I would bet Electra have revised theirs since this event :thumb:

FreshCoffee2

When you change out a boiler safety valve, you can tell if the path is safe or not (blocked) because there is nothing there but a sizeable hole. If its clear its clear, and if its blocked you can take appropriate action/s. If a boiler fails BEFORE a correctly working safety valve blows off, *I dont believe* (my opinion) the result will be anywhere near as dramatic as what happened in the photo, and I have (once or twice but no more in decades of my own experience) seen a boiler that has "popped" and become mis-shapen. *In my view* if a boiler fails because (after) the safety valve fails, then the issue is with the safety valve not the boiler so I cant see the point in testing a boiler and for all we know (another guess), the working pressurisation of an espresso machine boiler could / may be below a certain limit as to any "testing" rules and regulations....perhaps that is why there is no requirement that I know of, to periodically test esp machine boilers......who knows? Incidentally, the ORIGINAL "safety valve" as fitted to early espresso machines was virtually not much more than a hole in the top of the boiler with a weight on top. Rudimentary, but effective and probably less prone to "failure" than a modern valve....not that failures are common :thumb: After that I am not an engineer nor a legislator, and cant comment any further because we are all only getting into what ifs and wherefors. 🙂

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