.

Jason,

I know next to nothing about model boilers, but, that seems a remarkably loose interpretation of a 'Safety Valve' … It appears to be almost designed to give the operator a face-full of Steam … do they really get away with it ?

MichaelG.

Brian. A video on youtube may give you more detail on your Midwest boiler construction.

See Here

Mike.

I think these boilers are desisgned for use with small oscillators in mind. So any excess pressure would push the cylinder away from the port face.

But if they sell the boiler kit as a stand alone product, then they should provide a safety valve.

I would recommend drilling the top cap for a safety valve bush if you havn't already.

If you intend to use this with non oscillator type engines, silver soldering it may be more suitable. Without knowing to much about this particular boiler, other than what can be gleaned from the video above, a max working pressure of 10-15 psi would seem plenty.

I built a small boiler not so different to this one and it runs at a max 15psi, plenty for most small engines.

John

I think it would be a very good practice to silver solder your boiler Brain and to also fit some form of simple safety valve. But if you only need 15psi – why not set the safety at just above this (and not twice)?

IanT

By fitting a 15psi safety valve you are restricting the working pressure to just that 15psi, if you fit a 30psi safety valve the boiler has the potential to reach that given enough heat/time.

The design of the boiler would dictate it is only intended for low pressure applications. With a single flue and no additional bracing, fitting a 15psi safety valve would be well within the boilers design limits. Best to be on the side of caution with any boiler, no matter how small.

Testing of boilers is what may have you thinking about doubling the numbers, this is done at twice the max working pressure.

John

Damn my slow typing!

Edited By John Bromley on 31/10/2014 09:50:59

Brian,

Heres a link to a forum thats had a bit of interest on this boiler **LINK**

I think its really for the little oscillating engines rather than the bigger ones that you have built.

Still, its a nice little project to get started with.

Lofty

Brian,

You DO NOT 'run it up' to twice working pressure, its should be tested hydraulically so there is no chance of a dangerous instance if anything fails, the safety valve should be set so that pressure does not exceed 10% above normal operating pressure.

I'm not to sure how these regulations would apply to a little pot boiler like this as you have no pressure gauge to set the safety valve to, or sight glass to monitor the water level, ( the regs say that a water level indicator is not necessary as long as the supplied fuel runs out before a dangerous water level is experienced.

Boiler test code for info **LINK**

The fact is that what you do in the privacy of your own home is pretty much up to you Brian. But as pointed out in an earlier post, relying on the pipe "blowing off" may work in practice but will be messy and could result in scalds.

So, it would be very good practice to fit a safety valve and I imagine that the Mamod valve would be a simple solution in this case.

Regards,

IanT

I think this has come up before but never got an answer- After the boiler testing, at say 2x working pressure, is the safety valve tested and how ? Just interested.