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ZIEHL•ABEGG Axial Fan

Help needed connecting it up to power please.

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Neil Wyatt24/05/2016 17:08:39
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Posted by Howard Lewis on 24/05/2016 16:54:00:

Glad that Geoff now has the wind up!

With regard to boiler, or any pressure vessel, failures, think on the force produced from, say, 80 psi on a larger area. Would you want to be on the receiving end of even four square inches powered by 80 psi?

Interesting demo here:

blog.hsb.com/2015/04/06/sultana-boiler-explosion/

SillyOldDuffer24/05/2016 19:17:34
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Posted by Howard Lewis on 24/05/2016 16:54:00:

Glad that Geoff now has the wind up!

With regard to boiler, or any pressure vessel, failures, think on the force produced from, say, 80 psi on a larger area. Would you want to be on the receiving end of even four square inches powered by 80 psi?

Looks like 320 lbsF (145KgF) And that is a small proportion of the area of even a small boiler. Add steam, under pressure, with its temperature raised, to say 170C at 80 psi, from memory. Then comes the heat energy. The latent heat of vapourisation of one gramme of water at 100C is 536 calories, which will reappear as the steam condenses, PLUS the heat liberated in cooling from 170C to 100C, plus that of the water as it cools to body temperature (from 100 to 37C) and you would have a serious scald, liable to remove skin. (Sorry about the mixture of units, but you get the message?)

A former colleague lost a finger or two when a compressed air reservoir exploded, because of oil vapour entering it, at high temperature. (Not too different from what powers a diesel engine)

For what my advice is worth, treat all pressure vessels with care. The last thing that any of us want is someone being hurt, and our hobby being labelled as dangerous.

Howard

Many thanks for the analysis Howard. Your numbers and description of consequences convinces me. I hope no-one thinks that my suggestion that "the potential violence of model boiler explosions is overrated" is any reason to believe that small boilers are safe!

My comment was partly due to something overheard at the Bristol exhibition. A chap was telling a friend that a small traction engine happily steaming away was nothing but a bomb on wheels. That I doubt, at least compared with a actual bomb of the same size.

Consider what Wikipedia has to say about Nitroglycerin: "Detonation of nitroglycerin generates gases that would occupy more than 1,200 times the original volume at ordinary room temperature and pressure. The heat liberated raises the temperature to about 5,000 °C" And the same source gives the detonation velocity as 7700 m/s. That's a lot of energy released almost instantly.

So there you have it: conclusive proof that filling a steam boiler with Nitroglycerin is far more dangerous than filling it with water! I claim today's prize for stating the bleeding obvious...

Neil's link about full size boiler explosions is interesting as is this one too.

I've never heard of a serious accident involving a model steam boiler. That inspires confidence in their build quality, maintenance and responsible operation.

Cheers,

Dave

Cheers,

Dave

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