Roundhouse Jack Pressure Gauge problem
Posted: Sun Dec 15, 2013 9:55 pm
Hi all, I seek your collective wisdom?
My Roundhouse Jack class (original not special edition) developed an interesting fault when last steamed. The pressure gauge shot up to 60+ psi, whilst I was busy doing other things so I hadn't noticed the length of time it took to get to that level.
I assumed there was a problem with the safety valve and I cooled the engine, and put it to one side.
Now I have steamed it whilst watching, and the pressure went up to 60+ psi when only just warm, completely removing the pressure valve from the boiler (on a Jack it is the main filler as well) and the valve still stayed at 60 psi (ie when the boiler was completely de-pressured).
Releasing the pressure gauge allowed it to immediately rest to zero. There was a small amount of water in the syphon which I assume was turning to steam and causing pressure in the syphon. But this would infer a blockage between the syphon and the boiler pressure vessel itself. Applying back pressure with a 50ml syringe confirms no airflow backward on testing. Gentle probing with a wire through the syphon tube does not allow passage.
I am assuming some crud has blocked the tube.
I have tried heating the boiler with the pressure gauge removed; to try to blow any obstruction out. Initially there was a bead of hot water but that cleared and then no more.
Any comments about my diagnosis and any suggestions to free it. I have tried compressing the 50ml syringe (down to 7-10ml) before the syringe and tube leaks. I have tried a shot of butane with no effect (similar to unblocking gas jets) and I have tried gentle probing with wire.
Any help will be gratefully accepted.
Andy S at the Rylston Light
My Roundhouse Jack class (original not special edition) developed an interesting fault when last steamed. The pressure gauge shot up to 60+ psi, whilst I was busy doing other things so I hadn't noticed the length of time it took to get to that level.
I assumed there was a problem with the safety valve and I cooled the engine, and put it to one side.
Now I have steamed it whilst watching, and the pressure went up to 60+ psi when only just warm, completely removing the pressure valve from the boiler (on a Jack it is the main filler as well) and the valve still stayed at 60 psi (ie when the boiler was completely de-pressured).
Releasing the pressure gauge allowed it to immediately rest to zero. There was a small amount of water in the syphon which I assume was turning to steam and causing pressure in the syphon. But this would infer a blockage between the syphon and the boiler pressure vessel itself. Applying back pressure with a 50ml syringe confirms no airflow backward on testing. Gentle probing with a wire through the syphon tube does not allow passage.
I am assuming some crud has blocked the tube.
I have tried heating the boiler with the pressure gauge removed; to try to blow any obstruction out. Initially there was a bead of hot water but that cleared and then no more.
Any comments about my diagnosis and any suggestions to free it. I have tried compressing the 50ml syringe (down to 7-10ml) before the syringe and tube leaks. I have tried a shot of butane with no effect (similar to unblocking gas jets) and I have tried gentle probing with wire.
Any help will be gratefully accepted.
Andy S at the Rylston Light