|Philip Burley||07/01/2019 20:01:00|
|65 forum posts|
all the best for the new year , may your sheds be always dry . The plans for the Tich boiler don't show a blow down valve , some photos show them with some without . Is one needed or is it optional ,and could one be fitted to a boiler already made without damage to the integrity . Regards Phil
|Brian H||07/01/2019 20:10:45|
956 forum posts
They are a good idea, it means that you can empty the boiler after a steam up and blow out any foreign matter that might have entered.
One could be fitted to a boiler already made but it would be best to have a word with your boiler inspector, especially if the boiler has already been tested.
|257 forum posts|
A boiler blow-down valve is not needed for Tich. Access to any that you might fit on this loco is a bit tricky. Ideally you would want it/them on the front lower corner(s) of the water space in-front of the firebox. However with Tich this places it near the top of the very deep frames somewhere just forward and above the rear brake-hanger. Depending on your particular whim this area is blocked from above by the tanks. You could of course pierce a neat aperture in the frame to allow access, or arrange an operating lever somewhere convenient - especially if using an 'Everlast' style. I think you may find that access to the blow-down valve is also something that needs careful consideration on this particular loco. Not much help constructing your boiler with one - and then finding that you cannot get at it at all easily.
|Tim Taylor 2||08/01/2019 07:28:09|
|42 forum posts|
Blowdown valves have a couple of purposes. A bottom blowdown valve as Brian describes, allows you to blow out any crud that may have settled near the bottom of the lower drum or water legs..
A top blowdown valve is typically located below the minumum water level and is used to control the buildup of dissolved solids such as calcium and other ions left behind when the water is evaporated. If this isn't done, over time the concentration will build up to the point scaling can occur. On model engine boilers i doubt if this would be much of an issue. If the boiler isn't run continuously for long periods of time and flushed when you're done, you shouldn't have much of a problem.
|Jan B||08/01/2019 08:53:07|
15 forum posts
I have a blowdown valve fitted to my TICH. It is located in the middle of backhead just above the foundation ring. This means that I have access to the valve under the cab floor. The valve spindle is a stainless steel Alan screw and using a long Alan key it is very easy to operate.
The foundation ring on TICH is horizontal so blowdown valve doesn’t have to be located on the throatplate.
|Philip Burley||08/01/2019 09:45:34|
|65 forum posts|
Thanks for the help , I have a working Tich with a blow down valve , but I have acquired a larger boiler that I would lie to experiment with . It doesn't have a BD valve . If I try to silver solder a bush in now is it likely to ruin the boiler ?
|Paul Kemp||08/01/2019 18:02:00|
|145 forum posts|
Probably! Unless it is a brand new never been steamed example that is clean. You may get away with it then if you have a torch that can localise the heat mainly to the area of the bush.
|Nick Clarke 3||08/01/2019 22:03:29|
135 forum posts
Before you try to apply local heat (fortunately where a blowdown usually goes you are likely to have the option of oxy acetylene) you need someone to check there is no soft solder, including HMP stuff like Comsol on the boiler or you will certainly wreck it as has been suggested. Get an expert (club boiler inspector perhaps?) to go over it, and give you the all clear to proceed.
Please login to post a reply.
Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!
You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.
Click THIS LINK for full contact details.
For subscription issues please see THIS LINK.