Re: Real boiler pressure and its impact on t.e. and operations

rehunn Wrote:
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> You can do all sorts of mental gymnastics for this
> because that .85 factor is essentially for sea
> level. At 10,000 feet the boiling point for water
> is under 200 deg F
> which doesn't make much difference in the
> pressurized boiler but it does relate to more
> effectively making steam that last bit into the
> cylinders and since the
> atmospheric pressure is lower at 10,000 feet the
> effective differential across the piston is
> increased.

IIRC, at 10,00 feet, atmospheric pressure is about 4.5 PSI less than at sea level, and water boils at about 193 degrees, 19 degrees lower than at see level. At 215 PSIA(absolute), water boils at 388 degrees, however, at 210 PSIA, the boiling point only drops 2 dedrees to 386, not much of a savings.

Also there is no gain at the piston. The pressure gauge measures the difference between the pressure in the boiler and the atmospheric pressure, so with 5 PSI less atmospheric pressure there will be 5 PSIA less pressure in the boiler. Same thing with the safeties. The spring plus the atmosphereic pressure holds the valve shut. Reduce the atmosphere by 5 PSI, you reduce the popping pressure by the same amount.