boiler safety measures

[tjagiello]

I've posted some questions in the electrical section of these forums:

http://www.eng-tips.com/viewthread.cfm?qid=265034

and it's been suggested to post here as well for additional pointers, so here we go.

I've got a small boiler (200mm wide, 100mm dia) which has an 3/8" inlet hole, a solenoid valve controlled outlet (6mm dia) and a 2kW heater. It has a pump hooked up to it which can produce max 9bar of pressure and which will be on occasionally for less than a minute each time. The boiler heater will be controlled by a PID/SSR combo with a simple cut off switch to power up the loop. There will be an over-pressure valve mounted between the pump and the boiler and an additional check valve between the pump and the OPV/boiler. I'm also planning to add a thermal cut-out to further protect the boiler from explosion in case of a failure of any of the above. The boiler will be filled with water and set to 93-95*C and simply used to dispense water at a steady temperature (around 90-93*C).

Is there anything else that I need to add to make sure it fails safe in case of equipment failure?

Regards,
Tom

 

[unclesyd]

You might want to add a thermal relief valve to prevent the water being dispensed at too high a temperature.

http://www.rostravernatherm.com/thermal-relief.htm

If you can can you post a sketch of your proposed system.

 

[kbs]

A low water cutoff device (probe type) should be included. Protect the element as well as the vessel.