The steam boiler and espresso technology

[chris_ittner13]

Ok people it was about time to collect the various bits of coffee knowledge in to one area here at MAP. Pull and espresso and sit down and enjoy.

Here is a very specific question about espresso technology that has been on my mind for a while now:

Steam boilers are an integral part of many modern espresso machines (though not the only configuration used to make espresso either)... they're probably the most prevalent sort of technology behind commercial espresso machines on the market today.

So... it got me to thinking... steam boilers, like the hot water heater in your house are lined with glass... usually a very thin coating that is sprayed on them and then baked to fuse the glass into smooth surface on the interior of the boiler tank... probably no more than 1/8th inch or a few millimeters thick. The reason for this I'm guessing is to prolong the life of the heater against rust, corrosion and to keep metals and chemical contaminants from leaching into the water supply.

Surely whatever materials the steam boiler is built with it's got to be able to withstand high heat and high pressure.

So does anyone know if the boilers in espresso machines are glass lines?

Can they avoid having to use a glass lining by using stainless steel?

Is anyone familiar with building boilers or refurbishing older ones?

Below is the steam boiler and heating element from inside a Salvatore espresso machine. It's appears to be made of copper/brass. Though surely it must be constructed with some other materials and linings as you can't use straight copper and brass with food sources as it's would contaminate them with metal that end up in your system.

 

[Kerpal]

I found this discusion mooching around http://www.coffeegeek.com/forums/espresso/machines/328982 that seems to be covering what you want to know , if nothing else it seems like a good place to ask.

 

[KrisR]

Ah yeah. I'm a member over there actually but hadn't come across that thread. Thanks for the heads up. I should post in that thread because I'm curious how they're using bit boilers and bits but not getting any contamination from metals.
Interesting.

I figured it was a long shot to post here on MAP... but I thought perhaps there may be someone who tinkers with this sort of thing in their garage/workshop.

But kudos to you 16 views and only you posted so far.

 

[ABabyAteMyDingo]

I do know that some stainless formulas react more to steam than others, just like ordinary stainless is different from medical stainless. I also think copper can be used with straight water as the copper is not absorbed as much, I still have my great grandmothers giant copper jam pan which has seen a good 70+ years of service.

like this one only bigger takes 14lbs of fruit and 14 lbs of sugar.

 

[Johnnydeppluver]

Yeah- it's a matter for debate how injurious to your health using copper vessels for boiling stuff in can be. It's like lead- as long as you don't eat the stuff and you wash your hands after handling it, and wear masks when you melt it, it's not an issue.

 

[CHEVYSUCK]

Adoug,
Interesting... is the interior surface of that copper pot lined with anything?
Man that's a nifty thing to get to inherit.

The reason I ask is that I was always told that unlined copper pots were not safe to cook with. In general I've always avoided aluminium when I can... but for instance in my restaurant there is simply no way NOT to use aluminium pots. If you had go a day in the line with cast iron... you'd either be one buff mo-fo or half dead.

Though at home... I still use cast iron that's been in my family since my father was a kid. My father as well still uses cast iron that's he had for decades. From years of use it's perfectly seasoned and is basically the perfect no stick pan. Though I have to admit I cringe when I see the price on any of the top quality cast iron from Le Creuset

My eqq white/merengue whipping bowl is copper and cost a small fortune. But I only ever use it for egg whites and nothing else. Certainly nothing acidic. It's been around a good 10 years now so I figue it was a decent investment.

Here's an interesting bit I cam upon in regards to metals and cooking pots. I assume the same applies to boilers... perhaps even more so:

 

[ThomasVu]

These pictures look interesting http://images.google.com/imgres?imgurl=http://www.fullespressorepair.com/graphics/general_overhaul/boiler_clean.jpg&imgrefurl=http://www.fullespressorepair.com/beforeandafter.htm&h=576&w=768&sz=57&hl=en&start=19&tbnid=XE4U6tWf4Z99pM:&tbnh=107&tbnw=142&prev=/images%3Fq%3Despresso%252Bboiler%26start%3D18%26gbv%3D2%26ndsp%3D18%26svnum%3D10%26hl%3Den%26sa%3DN

 

[smallvilleismylife]

Friggin' brilliant... just the sort if images I need.

 

[holden_nick57]

Nope totally unlined, I was told that unless you have an intolerance of some kind even foods as acid as tomatoes will only absorb tiny amounts of copper, far less than the harmful amounts to humans. But still enough to kill of some microbiological contamination. Remember that in a pan that size you will have less surface area per pound of fuit.