Blow-off Apparatus

In a steam boiler, fixtures arranged to permit a certain quantity of the water in the boiler to be discharged to waste or into drains. a pipe with a valve in it is to the lowest point the boiler (to mud-drum, there is one), and by opening the valve, the solid matter which has settled at this point of most inactive circulation will be washed out by the flow to this point. Similarly also this valve will be used when the water in the boiler becomes too concentrated a solution of the soluble salts in the feed-water to be economically evaporated. Some of the waters which contain magnesia salts in solution make a floating scum on the surface of the water in the boiler. A surface blow-off apparatus would here be used, so that the water which escapes on opening the blow-off valve will be taken from the top instead of the bottom.