"To prevent or stop the engine from blowing off, the supply of water (not steam--SMD) should be increased or the damper dropped."
--Kirkman, Locomotive Fireman and Engineer's Handbook, 1906
"At ordinary working pressures, the difference between the temperature of the water in the boiler and the water of the entering feedwater is about 200 degrees F. When the engine is working the circulation is rapid and the temperatures soon equalize, but if the engine is standing, the temperatures equalize more slowly; the cooler water settles around the firebox sheets and damage results from the contraction that follows." (emphasis added)
--ICS, Locomotive Management, 1928, 1937
"By now the firebox and the brick arch should have achieved sufficient heat to overcome the dual cooling effect of the injector placing water in the boiler and coal cooling the firebed." (emphasis added)
--The engine Driver's Manual, 1998
Sorry--didn't find anything about the steam used in the injector causing the boiler pressure to drop.
