Definitely Walter, a steam engine gives you maximum torque from the first inrush of steam to the cylinder and does not require a gearbox interposed between engine and drive to increase the torque.
A pressure cooker will cook potatoes et al in a quarter the time of an open saucepan because of the five pound weight of the safety valve.
If your wife has a pan on the cooker and it's lid is bobbling about with the escaping steam, she is wasting your money, the ingredients will not cook any quicker than they would if the heat source were turned down so that only a whisper of steam escaped.
At sea level, water boils to produce steam at 100deg centigrade in an open pan, kettle etc. and it will continue at 100deg no matter how much more heat you apply to the saucepan. The only way to get the water hotter is to restrict the steam's escape, creating a pressure, so a boiler is a totally enclosed container to restrict the steams escape, this creates a pressure, which in turn increases the steam's latent heat. The boiler of course must be designed and built to withstand that pressure, and a safety valve fitted, along with several other safety devices, to allow the steam to escape when the design pressure is reached.
Boilers are very dangerous if abused, some of the early train driver's found out that if you screwed down the safety valve, or stuck a brick on it, the pressure would increase in the boiler, and the engine would do more work, go up a hill faster or pull more wagons, unfortunately, for the driver and anyone within fifty yard or so of that boiler, if the increased pressure exceeded the design pressure of the boiler, it would quite likely split it's seams with disastrous consequences, and on several noteable occasions, they did just that.
Every fourteen months, all steam boilers have to have a hydraulic pressure test to twice the working pressure. This entails filling the boiler with cold water, then attaching a hand pump to the boiler and pumping in additional water thus increasing the pressure within the boiler up to it's test pressure, which in the case of my hospital boilers, with a working pressure of 150psi/sq inch, was 300lbs/sq inch. With a full boiler, it takes very little extra water to raise the pressure in the boiler to it's test pressure, so if the boiler should split during the test, it would only have to throw a gallon or two of water out to get back to atmospheric pressure, not 20,000 lbs of steam released into the atmosphere at, without my steam tables I don't no the exact temperature of the steam, but lets say you would have a hard boiled egg in considerably less than four minutes, if you were still alive to eat it.
If anyone thinks the fourteen month interval is a strange interval to set for the test, this is so that a more logical period of twelve months is allows you to contact the insurance engineer and allow for unseen delays taking you past the fourteen month deadline and causing an illegal operation of the boiler.
Of course, if you were daft enough to try to keep to the deadline of fourteen months, and something went amiss, you would be in deep do dah.
Regards,
Brian.
