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RocDoc

Testing a boiler

Hi everyone,

I'm just wondering what would be the best way to test a home made boiler which is not connected to an engine.

Many thanks

Pete
Roly Williams

Re: Testing a boiler

RocDoc wrote:
Hi everyone,

I'm just wondering what would be the best way to test a home made boiler which is not connected to an engine.

Many thanks

Pete

What sort of boiler is it? Is it a small/low pressure (Mamod style) one or a big/high pressure one?
RocDoc

Hi Roly,

Small, low pressure Bowman type boiler 4.5" long by 1.5" diameter, built for my Swallow restoration.

Pete
Roly Williams

That makes life a lot simpler. If it were a large or high pressure one then you'd need get it professionally tested. However, that's not necessary in this case.

First thing to do is check for leaks. The easiest way to do that is to block off all holes except one and attach a source of air to the last one (a bicycle pump would do). Imerse the boiler in a bucket of water and pump up to a lowish pressure. Any leaks will be obvious.

To be safest, you should then hydraulicly test it to more than it's working pressure. Fill it up completely with water, and attach a water pump and pressure gauge. Pump it up to about 1.5 times the working pressure and hold it there for a few minutes.

If it doesn't spring a leak with cold water then steam it up slowly, keeping an eye open for leaks. Be ready to remove the heat quickly if necessary.
kevininasia

I did something similar once with a home-made boiler. I used the water pump from my Wilesco D21 and the pressure gauge from my Marklin, which tops out at 6 bar. It was very easy to pump the boiler up to 5 bar (75 psi). I didn't want to go any higher for fear of wrecking the gauge. The whole setup held for about 15 mins with no leaks, and I released the pressure. It was all a lot simpler than I had expected.
RocDoc

Hi Roly and Kevin,

Thank you for your help.  Will try the bucket of cold water first.  

I don't have a water pump nor a pressure gauge (to fit a Bowman SV thread ... is it possible to get these somewhere?).  If it doesn't leak under water I'll try a slow steam up test.

Cheers

Peter
Roly Williams

RocDoc wrote:
Hi Roly and Kevin,

Thank you for your help.  Will try the bucket of cold water first.  

I don't have a water pump nor a pressure gauge (to fit a Bowman SV thread ... is it possible to get these somewhere?).  If it doesn't leak under water I'll try a slow steam up test.

Cheers

Peter

TBH, that's what I do. If you're reasonably confident about your soldering and it doesn't leak then it's not going to explode.
benchmark

Good advice you have gotten forn the guys there above.

If you are planning to make more boilers in future , this maybe a good investment,

http://cgi.ebay.co.uk/PLUMBERS-SY...umbing_MJ&hash=item4aa53652ea

I know Andreas who makes the KMV engines has something similar for his line of engines.
46u

I use a PMR water feed pump to hydro test my boilers as well as a water feed pump. Great dual purpose pump.  

http://www.pmresearchinc.com/stor...uctid=3114&cat=111&page=1

H2o vapour

Hi Pete,

Interesting point,

I used to do presure tests many years ago as part of my job. Once did a 3500 PSI test for Boots in Nottingham.

I would suggest you test to 1.5 times SV pressure. The rig that 46U has posted is excellent.

But the point is that you can rig anything up do the job, looks are not important. We always used to be keen on getting all air out of the test item, air is compressable and will give unstable readings.

We always used to leave it for 1/2 hour min. If you have a drop in pressue you need to find out why, if pressure increases don't worry as long as it not to much that it does damage.

Any gauge will do, as long as it can be part of the live side of the rig, it can go on the pump assembly if not able to fit a boiler thread. You could even pump up with a bike pump suitably adapted and use vales to close off when at pressure, again as long as the gauge is on the live side.  

Hope this helps, do you want to see the Swallow on Sunday at STIA?

Cheers

Mark H2o
RocDoc

Hi Mark,

Thanks for the advice.  Did a bit of boiler testing tonight.  I used a bicycle foot pump (which has a pressure gauge) with the air home end fitted over the steam pipe, and with the boiler under water.  It worked ... just.  Glad that I did as there was a bit of a leak from the steam dome/boiler join.  Had to do a bit more soldering tonight.

I'm sorry but it looks like that I won't be able to make STiA this year.  Too many other family commitments.  Ah well.

Thanks again.

Pete
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