Author Topic: Removing the safety valve in a stove top moka pot  (Read 1978 times)

Gattopardo

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Removing the safety valve in a stove top moka pot
« on: November 10, 2018, 08:04:41 pm »
I have a brikka stove top coffee pot that I suspect has a faulty pressure valve, as the valve seems leak steam. Would you you replace it with a bolt so could see if the problem is the valve or something else.  Here is a diagram to show the idea of where the valve is:


The worry for me is that the brikka has a weighed adaptor on top of the made coffee spout, to make a sort of crema on the coffee.

  So would that mean extra attention?

ElyDave

  • Royal and Ancient Polar Bear Society member 263583
Re: Removing the safety valve in a stove top moka pot
« Reply #1 on: November 10, 2018, 08:18:43 pm »
Do not EVER block off a safety valve, under ANY circumstances.

Give it a very good scrub internally and externally, both halves of the pot.
“Procrastination is the thief of time, collar him.” –Charles Dickens

Kim

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Re: Removing the safety valve in a stove top moka pot
« Reply #2 on: November 10, 2018, 09:32:46 pm »
Quite.  Steam explosions can ruin your day faster than you can say "BLEVE".
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Gattopardo

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Re: Removing the safety valve in a stove top moka pot
« Reply #3 on: November 10, 2018, 09:40:46 pm »
Do not EVER block off a safety valve, under ANY circumstances.

Give it a very good scrub internally and externally, both halves of the pot.

The problem is the valve, the rubber seal has gone.


Seeing as I don't tamp the coffee, and the coffee is not a fine ground it should not be a problem.

ElyDave

  • Royal and Ancient Polar Bear Society member 263583
Re: Removing the safety valve in a stove top moka pot
« Reply #4 on: November 10, 2018, 09:45:29 pm »
No, just no.

Safety consultant, chemical engineer here, and Kim. Just NO.

If you know the seal has gone, replace the seal. Anything else is just fucking stupid.
“Procrastination is the thief of time, collar him.” –Charles Dickens

Re: Removing the safety valve in a stove top moka pot
« Reply #5 on: November 10, 2018, 10:32:15 pm »
Do not EVER block off a safety valve, under ANY circumstances.

Give it a very good scrub internally and externally, both halves of the pot.

The problem is the valve, the rubber seal has gone.



I suspect that it ought to be possible to fit a new seal by pulling it out/poking it in through the hole on the pressure side of the valve, once the valve is pulled open. Before you do that, do make sure that it isn't just a rogue coffee ground jammed in the seal, making it leak.

FWIW the Brikka is a bit more like a steam bomb than the other Bialetti models, because it has a weighted pressure valve (a bit like a pressure cooker I think). Running it without a functional safety valve would be completely mental. With any such machine there is a chance that coffee will jam the holes inside and cause an excess pressure inside.

You ought to be able to test the safety valve without any risk by (say) using a bicycle pump (with a gauge) on it.

cheers


Ben T

  • What you saying, then?
Re: Removing the safety valve in a stove top moka pot
« Reply #6 on: November 10, 2018, 10:33:57 pm »
Do not EVER block off a safety valve, under ANY circumstances.

Give it a very good scrub internally and externally, both halves of the pot.

+1

And turn the heat down you nutter!

Mine spews steam out the valve if I have the hob on 9 for the entire extraction, but not if I have it on 5.

If I want it quick I bring it to the boil on 9, but turn it down to 5 once it starts to produce.

My understanding of physics is that expanding steam could easily beat welded steel joints in a battle of strength. The whole thing could blow apart and send fragments everywhere. Don't think about blocking the valve, get a new one if it's not working.

Edit: mine has got a safety valve on the SIDE of the water chamber. Are we talking here about one that has got the safety valve in the top, ie where the coffee comes out?
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FifeingEejit

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Re: Removing the safety valve in a stove top moka pot
« Reply #7 on: November 10, 2018, 10:46:13 pm »
Quite.  Steam explosions can ruin your day faster than you can say "BLEVE".

A hiking club mate once in his professional capacity attended the scene of a pressure cooker explosion...
https://www.bbc.co.uk/news/uk-scotland-tayside-central-29125339


His description of the scene is considerably more graphic than any of the press reports were which generally limited themselves to "lost part of a leg" presumably so that their readers could finish their breakfasts without ejecting them.

Re: Removing the safety valve in a stove top moka pot
« Reply #8 on: November 14, 2018, 04:53:12 am »
The valve is designed to regulate the pressure.
Quote
Designed to enhance your coffee drinking experience, the Brikka is equipped with a special patented valve that regulates just the right amount of pressure, producing the perfect froth every time..
https://www.bialetti.com/coffee/stovetop/brikka/spare-parts-c-1_7_24_34.html

So as ∆ upthread ∆ Service it, then use less heat!

I have always used boiling water in this type of coffee maker to speed the process. I also think a kettle uses less energy for the initial water heating.

Re: Removing the safety valve in a stove top moka pot
« Reply #9 on: November 14, 2018, 11:24:40 am »
In most diving regulators, the 2nd stage (the bit in the diver's mouth) is the pressure relief in case the 1st stage (the bit attached to the top of the air cylinder).

Fitting the wrong 2nd stage, or blocking the connection to the 2nd stage has several time resulted in the next-weakest item failing. Someone who did that told me that the remaining hose burst, and the far end of the hose was found 50m away.

Taking the pressure relief off the aluminium superheated steam bomb is not a good idea, even temporarily.

Quote from: Kim
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Re: Removing the safety valve in a stove top moka pot
« Reply #10 on: November 24, 2018, 08:50:05 pm »
Compressed air isn't a totally safe test either.  Water is best as nothing is going anywhere if the pressure vessel splits.
Never tell me the odds.

Feanor

  • It's mostly downhill from here.
Re: Removing the safety valve in a stove top moka pot
« Reply #11 on: November 24, 2018, 08:56:28 pm »
Pressure tests are generally not conducted with any gas!
It's much too compressible, and the stored energy is high.

Pressure tests are usually done with water or another fluid with low compressibility.
Much less stored energy.

So if it fails, it fails with a phut, not a bang.

T42

  • Gaulois réfractaire
Re: Removing the safety valve in a stove top moka pot
« Reply #12 on: November 25, 2018, 05:17:54 pm »
My daughter had a wee Bialetti 1-cup "pot" that had a bent-over tube instead of an upper chamber, and delivered the coffee straight into the cup. She got something or other blocked and had to remove the top of the pot from the ceiling. A couple of seconds earlier she had been bending over it. Chum in the dim & distant had to de-coffee his kitchen walls, too. Just sayin'
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ElyDave

  • Royal and Ancient Polar Bear Society member 263583
Re: Removing the safety valve in a stove top moka pot
« Reply #13 on: November 25, 2018, 05:28:15 pm »
just an over exuberant or prematurely bottled homebrew wine can spread far and wide and that's without the energy of steam.
“Procrastination is the thief of time, collar him.” –Charles Dickens

yorkie

  • On top of the Galibier
Re: Removing the safety valve in a stove top moka pot
« Reply #14 on: November 25, 2018, 06:23:03 pm »
Pressure tests are generally not conducted with any gas!
It's much too compressible, and the stored energy is high.

Pressure tests are usually done with water or another fluid with low compressibility.
Much less stored energy.

So if it fails, it fails with a phut, not a bang.

My father is the proud owner of a 1915 steamroller. Every spring he has his annual appointment with his boiler inspector. This starts with a visual inspection, using cameras and the mk1 eyeball, then progresses to a hydraulic test, where water is pumped into the boiler to a greater pressure than the normal maximum working pressure - usually about 20% over, I think. (I could be wrong with the 20%, it may be 25% or more!)

If there are no leaks with water, the inspector makes an appointment for another visit to test it under steam. They don't do that the same day, as it takes a while to get the water level back down to normal and to raise steam to working pressure - 125 p.s.i. in the case of the father's engine. Once the boiler passes the steam test, the inspector issues a certificate stating that the boiler is passed safe for 14 months.

Everybody who has a steam powered vehicle has to pass these tests, the insurance companies don't mess about when it comes to insuring something that can cause a *lot* of damage when it goes **phut** - it makes letting the magic smoke out look like a Sunday school picnic, if you'll pardon the mixed metaphor!
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LittleWheelsandBig

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Re: Removing the safety valve in a stove top moka pot
« Reply #15 on: November 25, 2018, 06:30:15 pm »
In Germany, the whole concept of national quality and inspection systems developed from steam boilers and the deaths resulting from not consistently inspecting them. https://www.tuv-sud.com/about-tuev-sued/history/part-1-1866-1900
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ElyDave

  • Royal and Ancient Polar Bear Society member 263583
Re: Removing the safety valve in a stove top moka pot
« Reply #16 on: November 25, 2018, 06:34:10 pm »
In Germany, the whole concept of national quality and inspection systems developed from steam boilers and the deaths resulting from not consistently inspecting them. https://www.tuv-sud.com/about-tuev-sued/history/part-1-1866-1900

Pretty much the same in this country as well
“Procrastination is the thief of time, collar him.” –Charles Dickens

Salvatore

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Re: Removing the safety valve in a stove top moka pot
« Reply #18 on: November 26, 2018, 01:38:08 pm »
My husband and I refer to our one of those as "the exploding machine", because he had one explode when he was staying in a holiday rental property a long time ago. Fortunately no one was near it. It made a lot of mess, apparently. Coffee everywhere...

ian

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ElyDave

  • Royal and Ancient Polar Bear Society member 263583
“Procrastination is the thief of time, collar him.” –Charles Dickens

T42

  • Gaulois réfractaire
Re: Removing the safety valve in a stove top moka pot
« Reply #21 on: November 26, 2018, 03:24:05 pm »
Before the advent of pressure cookers, exploding cookpots and cauldrons were not uncommon. The cook would put the lid on, seal the rim with pastry, and then rope it down firmly.

https://books.google.fr/books?id=N-u0AwAAQBAJ&lpg=PP1&dq=dorothy%20hartley&pg=PT24#v=onepage&q=dorothy%20hartley&f=false
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Re: Removing the safety valve in a stove top moka pot
« Reply #22 on: November 27, 2018, 04:46:31 pm »
Pressure tests are generally not conducted with any gas!
It's much too compressible, and the stored energy is high.

Pressure tests are usually done with water or another fluid with low compressibility.
Much less stored energy.

So if it fails, it fails with a phut, not a bang.

My father is the proud owner of a 1915 steamroller. Every spring he has his annual appointment with his boiler inspector. This starts with a visual inspection, using cameras and the mk1 eyeball, then progresses to a hydraulic test, where water is pumped into the boiler to a greater pressure than the normal maximum working pressure - usually about 20% over, I think. (I could be wrong with the 20%, it may be 25% or more!)


We make pumps here for the offshore oil and gas industry. All of our pressure casings are tested with water at 50% over rated pressure to ensure they won't go *phut* on an oil rig. I would imagine a boiler test at 50% is also quite reasonable.
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yorkie

  • On top of the Galibier
Re: Removing the safety valve in a stove top moka pot
« Reply #23 on: November 27, 2018, 05:56:09 pm »
Pressure tests are generally not conducted with any gas!
It's much too compressible, and the stored energy is high.

Pressure tests are usually done with water or another fluid with low compressibility.
Much less stored energy.

So if it fails, it fails with a phut, not a bang.

My father is the proud owner of a 1915 steamroller. Every spring he has his annual appointment with his boiler inspector. This starts with a visual inspection, using cameras and the mk1 eyeball, then progresses to a hydraulic test, where water is pumped into the boiler to a greater pressure than the normal maximum working pressure - usually about 20% over, I think. (I could be wrong with the 20%, it may be 25% or more!)


We make pumps here for the offshore oil and gas industry. All of our pressure casings are tested with water at 50% over rated pressure to ensure they won't go *phut* on an oil rig. I would imagine a boiler test at 50% is also quite reasonable.
Upon checking with t'father, he has confirmed that the hydraulic test is indeed 50% over normal working pressure. Turns out that my memory is faulty (not that that comes as a surprise!)

When the boiler was originally built, (worth mentioning that this is the 3rd boiler this engine has had) the initial test was to double the intended maximum working pressure, as a one-off. Every test since is to 50% over - in his engine's case 250 p.s.i. initially, then 187.5 p.s.i. annually.
Born to ride my bike, forced to work! ;)

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Re: Removing the safety valve in a stove top moka pot
« Reply #24 on: November 27, 2018, 08:35:21 pm »
Has anyone noticed that genuine Bialetti moka pots are designed for left-handers?  If you're right-handed, the safety valve always ends up pointing right at you when the pot is on the hob.  Cheap imitations seem to avoid this flaw.
Never tell me the odds.