Wednesday, 12 October 2016

Alfred passes his steam test

Miniature live steam locomotives have to have their boilers certified as safe by a boiler inspector to obviate the possibility of a catastrophic boiler explosion, just like full size locomotives. Alfred's boiler has a maximum working pressure of 80psi, and at that pressure water in the boiler will be at several hundred degrees centigrade. If the boiler were to rupture, that water would instantly flash to steam as the pressure is released, liberating enormous amounts of destructive energy.

A new boiler has to be hydraulically tested (pressurised with cold water) to twice working pressure and checked for absence of water leaks. Water is effectively incomprehensible so a boiler rupture even at that high pressure will mean you might get wet - nothing more serious than that.

Thereafter, every four years the boiler has to be hydraulically tested to 1.5 times working pressure. In addition, there is an annual steam test. When I bought Alfred almost a year ago he came with a 'new' hydraulic and steam test certificate, so his steam test is due about now. Without a valid boiler certificate the locomotive should not be steamed even at home, and club boiler insurance for the loco is invalid.

Last Sunday at Urmston I asked the club boiler inspector to perform a steam test on Alfred. Here's how it went.

Photos by Jason Lau.

 Here Bob checks the injectors are working. First I'd removed the steam pressure gauge so Bob could ensure that it was correctly calibrated, then, having replaced it, I steamed Alfred, and Bob checked that the safety valves blew off at 80psi (Alfred's max working pressure) and maintained the boiler pressure at no more than that despite the blower being full on to give a white hot fire. Next, Bob checked that both injectors, and the hand pump in the tender, can deliver feed water to the boiler.

Smiles of relief from me and a thumbs up from Bob as Alfred passes the steam test 

So, as we have Alfred in steam, and he's legal to operate, we might as well run him. Here I push him off the prep bay and onto the traverser to move him to the running track. 

Alfred on the traverser 

Pulling the traverser across towards the entry branch for the running track 

At the end of the entry branch is another traverser for access to the main and inner running tracks. Here, Alfred waits for me to move the traverser into position to transition him across to the running track. 

 I did one circuit of the main track and though I arrived back at the station with plenty of steam (he was blowing off) his fire needed attention as did the boiler water level, and I needed a few minutes to get him ready for another lap. However, passengers were waiting for rides and the bigger five inch gauge engines were ready to take them, so I moved Alfred to the inner track which is is more appropriate to his capabilities.

There was plenty more going on at Urmston on Sunday, as some of Jason's other pictures show: 

Another lovely Sunday in the park; not bad for well into October. We really have enjoyed some great weather this summer and autumn.

A nice BR standard class 9F on the prep bay 

Club member Dave Roberts has some lovely locos, including the Black Five I drove last week, an unusual Beyer Peacock Venezuelan Tank, and this very neat Garratt  

The busy prep bays early in the day. Alfred and me behind the chairman's rebuilt Scot in the foreground. 

Three big BR Standards  - two 9Fs and a Britannia 

 Dave drives his Garratt round the big track


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