Microcimbali Safety Valve - Page 2
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cafetta.mini (original poster)
- Posts: 22
- Joined: 4 years ago
Hi Gary,
Yes, this is very helpful indeed. Again, your effort and time are very much appreciated. I think the concern for the buyer is that if it were to be tightened too much, the pressure wouldn't be released before it should and hence not make the machine safe.
Yes, this is very helpful indeed. Again, your effort and time are very much appreciated. I think the concern for the buyer is that if it were to be tightened too much, the pressure wouldn't be released before it should and hence not make the machine safe.
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drgary
- Team HB
- Posts: 14394
- Joined: 14 years ago
He can test it with a steam wand manometer to adjust it just right. It's him wanting to tune his Microcimbali. That's not a problem with the safety valve malfunctioning.
Gary
LMWDP#308
What I WOULD do for a good cup of coffee!
LMWDP#308
What I WOULD do for a good cup of coffee!
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Sw1ssdude
- Posts: 301
- Joined: 6 years ago
Could you send a picture of the whole machine? there are two types of heating, one of them relies on constantly steaming from the top. One can tell by the switches which microcimbali it is (italian rocker switches = constant steaming, green on/off-button: no steaming)
For safety valve adjustment:
I did the same thing on my coffee machine, after i replaced the (rock hard) rubber gasket in the safety valve.
the gasket was held down with a spring, and the spring compression could be adjusted with a hex key. When the boiler pressure overcomes the spring force, the safety valve opens and vents until the spring overcomes the dropping boiler pressure.
I hotwired my pstat, so that it is constantly on, let the pressure build up to 1.8 Bar, and then backed out the screw which held down the newly installed rubber gasket, until it popped open and vented the boiler (CAUTION: Overpressured Steam is even hotter than regular steam!!!), now i know that at 1.8 Bar my safety valve will go off. then i put the pstat back into the circuit. 1.8 just sounds right, for me, and my machine. and most machines, i'd say.
(the rubber gasket relaxes over the years, making room for the spring, lowering the treshold for the safety valve. If this treshold drops below the pstat-off-pressure, the pstat remains constantly on, as the safety valve constantly vents, and the only thing between you and a catastrophic failure is the thermal fuse switch).
a safer way to get high pressure is to simply set the pstat to a high pressure, instead of hotwiring. the importance is: safety valve treshold must be (and remain) higher than upper pstat pressure.
Also:
i (not so fondly) remember my Microcimbali spewing water in all directions from the check valve: as soon as i vented the steam wand, the dropping pressure caused the overheated water to boil and rise to the top where the valve sits, just as beer foams when you take the bottlecap off. this turned my cimbali into a Geyser. one of the reasons why i sold it off...
Invite your buyer to the HB forum, where he can learn how to tame his new to him, italian, and very temperamental machine, that will be of more help than sending him parts, i guess...
For safety valve adjustment:
I did the same thing on my coffee machine, after i replaced the (rock hard) rubber gasket in the safety valve.
the gasket was held down with a spring, and the spring compression could be adjusted with a hex key. When the boiler pressure overcomes the spring force, the safety valve opens and vents until the spring overcomes the dropping boiler pressure.
I hotwired my pstat, so that it is constantly on, let the pressure build up to 1.8 Bar, and then backed out the screw which held down the newly installed rubber gasket, until it popped open and vented the boiler (CAUTION: Overpressured Steam is even hotter than regular steam!!!), now i know that at 1.8 Bar my safety valve will go off. then i put the pstat back into the circuit. 1.8 just sounds right, for me, and my machine. and most machines, i'd say.
(the rubber gasket relaxes over the years, making room for the spring, lowering the treshold for the safety valve. If this treshold drops below the pstat-off-pressure, the pstat remains constantly on, as the safety valve constantly vents, and the only thing between you and a catastrophic failure is the thermal fuse switch).
a safer way to get high pressure is to simply set the pstat to a high pressure, instead of hotwiring. the importance is: safety valve treshold must be (and remain) higher than upper pstat pressure.
Also:
i (not so fondly) remember my Microcimbali spewing water in all directions from the check valve: as soon as i vented the steam wand, the dropping pressure caused the overheated water to boil and rise to the top where the valve sits, just as beer foams when you take the bottlecap off. this turned my cimbali into a Geyser. one of the reasons why i sold it off...
Invite your buyer to the HB forum, where he can learn how to tame his new to him, italian, and very temperamental machine, that will be of more help than sending him parts, i guess...
Lean Mean Caffeine Machine
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cafetta.mini (original poster)
- Posts: 22
- Joined: 4 years ago
Hi fellow 'Swissdude',
Thanks a lot for your in-depth reply! It's the one with the illuminated green on/off switch. I'll post a couple pictures once I'm home. Wow, that's quite the procedure you went though there!
Yes, it is indeed a moody machine and it took us a while to figure out how to make good coffee with it. Thankfully we never had a geyser experience...
Thanks a lot for your in-depth reply! It's the one with the illuminated green on/off switch. I'll post a couple pictures once I'm home. Wow, that's quite the procedure you went though there!
Yes, it is indeed a moody machine and it took us a while to figure out how to make good coffee with it. Thankfully we never had a geyser experience...
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cafetta.mini (original poster)
- Posts: 22
- Joined: 4 years ago
I'll also put this here, as it ties in well with the topic:
https://www.kaffee-netz.de/threads/micr ... ht.115927/
Some nice pictures of someone taking apart the valve.
https://www.kaffee-netz.de/threads/micr ... ht.115927/
Some nice pictures of someone taking apart the valve.
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Sw1ssdude
- Posts: 301
- Joined: 6 years ago
aha.
Well, if it can be disassembled, it can be cleaned. it seems to be a full metal construction, so it has no rubber parts that go bad with age.
but the steel ball will only seal on an absolute perfect brass surface. so, i'd clean the brass body with Durgol or citric acid, and then polish it with Sigolin or similar brass polish. maybe ever so slightly de-burr the vent hole with a common 45-degree countersink bit (just by hand, not with power tools or even a lathe).
and really check the ball for dirt, or corrosion. sometimes this is hard to see on the spherical reflection. replacements can be found very easily (and cheap) at your local bicycle shop (old bicycles have loose-ball wheel bearings).
once it seals properly, one could shim the spring, to adjust the spring tension for setting a specific pressure treshold. but this seems to be a lot of work. Also, the valve will eventually start to weep again.
if you can determine the thread size on the brass body, the valve could be replaced with a proper adjustable, rubber sealed valve. on the newer microcimbalis, the valve does not protrude through the decorative top cap, so if you find one that is short enough, you might be all set.
or have your buyer come to terms that he bought a very italian machine... Italy came up with lots of good things and inventions. But in my (mostly vehicle-based) experience, italian engineering is very..... Temperamental. I know of no one who bought an old Vespa, or Lancia, or Ferrari, for its low maintenance and high reliability...
Well, if it can be disassembled, it can be cleaned. it seems to be a full metal construction, so it has no rubber parts that go bad with age.
but the steel ball will only seal on an absolute perfect brass surface. so, i'd clean the brass body with Durgol or citric acid, and then polish it with Sigolin or similar brass polish. maybe ever so slightly de-burr the vent hole with a common 45-degree countersink bit (just by hand, not with power tools or even a lathe).
and really check the ball for dirt, or corrosion. sometimes this is hard to see on the spherical reflection. replacements can be found very easily (and cheap) at your local bicycle shop (old bicycles have loose-ball wheel bearings).
once it seals properly, one could shim the spring, to adjust the spring tension for setting a specific pressure treshold. but this seems to be a lot of work. Also, the valve will eventually start to weep again.
if you can determine the thread size on the brass body, the valve could be replaced with a proper adjustable, rubber sealed valve. on the newer microcimbalis, the valve does not protrude through the decorative top cap, so if you find one that is short enough, you might be all set.
or have your buyer come to terms that he bought a very italian machine... Italy came up with lots of good things and inventions. But in my (mostly vehicle-based) experience, italian engineering is very..... Temperamental. I know of no one who bought an old Vespa, or Lancia, or Ferrari, for its low maintenance and high reliability...
Lean Mean Caffeine Machine
