How much pressure can an HX steam boiler hold?

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frankmoss
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#1: Post by frankmoss »

Maybe this is crazy but I've been thinking about making a DB machine. Could I use an HX boiler as the brew boiler? Mainly, can it hold 9 bars of pressure? I know the HX tube can but I don't know about the rest of the boiler. Seems like it should be able to since it's much thicker than the pipes that hold 9 bars.

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HB
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#2: Post by HB »

IIRC, the boilers I've seen have a steam pressure release valve that opens around 1.6 bar and are factory tested around 2.0 bar. I have no idea if they could withstand 9 bar, but it's reasonable to assume they were not constructed with that usage in mind. :shock:
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frankmoss (original poster)
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#3: Post by frankmoss (original poster) »

Hmmm. I could switch out the safety valve if I knew that the boiler could hold the pressure. Anyone tried this?

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Psyd
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#4: Post by Psyd replying to frankmoss »

Nah, most of us use the pump or the lever to generate the 9 bar of pressure. Raising the temperature of the water til it reached 9 Bar would put it at, oh, say 350 degrees F?
Most DB's have the brew boiler at a lower temp (pressure) than the steam boiler.
Or I'm missing something really important in the question?
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frankmoss (original poster)
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#5: Post by frankmoss (original poster) replying to Psyd »

I mean just forget the HX part and use the boiler like the brew boiler in a DB. I don't care about steaming. I would remove the vacuum breaker fill the boiler completely full. Basically, could an HX boiler function as a brew boiler?

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Psyd
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#6: Post by Psyd »

frankmoss wrote:I mean just forget the HX part and use the boiler like the brew boiler in a DB.
Unless I have this all wrong, the brew boilers in DB's are not pressurised to 9 bar. They are pressurised from .7 to 1.0 Bar and the pump is downstream of the boiler.
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frankmoss (original poster)
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#7: Post by frankmoss (original poster) replying to Psyd »

I was under the impression that the boiler was pressurized to 9 bar. I don't think the pump can be downstream because pumps cant handle hot water.

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erics
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#8: Post by erics »

Lots of boilers, both hx and brew, are fabricated from copper tubing and typically have a wall thickness of 3.0 mm or ABOUT 1/8". At least two examples of current DB machines (Expobar Brewtus & Vibiemme) have identical vessels for steam and brew, AFAIK.

The allowable pressure in these would be AROUND 350 psi = ~ 24 bar as per this: http://www.copper.org/applications/plum ... #prodspecs
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gyro
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#9: Post by gyro »

Psyd wrote:Unless I have this all wrong, the brew boilers in DB's are not pressurised to 9 bar. They are pressurised from .7 to 1.0 Bar and the pump is downstream of the boiler.
The pump is upstream of the boiler in the cold water. In a saturated group at least, there really is nothing significant (pressure-wise, excluding the influencing effects of glicuers etc) downstream of the brew boiler other than the pf, where pressure is again reduced to atmospheric.

keepitsimple
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#10: Post by keepitsimple »

frankmoss wrote:Maybe this is crazy but I've been thinking about making a DB machine. Could I use an HX boiler as the brew boiler? Mainly, can it hold 9 bars of pressure? I know the HX tube can but I don't know about the rest of the boiler. Seems like it should be able to since it's much thicker than the pipes that hold 9 bars.
Hi,

I'm not too sure about boilers from an old hx machine, as they wouldn't necessarily have been fabricated to withstand the pressure. You may well be OK, but a better option would be to get a boiler from a single boiler machine - something like an Isomac Zaffiro or similar. That will have been made for exactly the purpose you want.

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