The most important thing in connecting the relief to return pipes is, that it should always be carried down below the line, the same as all vertical return pipes. In connecting the reliefs, so that the lower opening can at any time be exposed to the steam, there will be the difficulty of having the steam going in one direction, and the water in another.
The relief pipe should “tap” the steam at its lowest or most depressed points. It should always be put in at the base of all steam “risers” taking steam to upper floors.
In leaving the boiler with main steam pipe, raise to a height that will allow of one inch fall from the boiler to every ten feet of running steam pipe; this is sufficient, and a greater fall or pitch will cause the condensed water in the pipe to make at times a disagreeable noise or “gurgling.”
The flow pipe should never start from the boiler in a horizontal direction, as this will cause delay and trouble in the circulation. This pipe should always start in a vertical direction, even if it has to proceed horizontally within a short distance from the boiler. Reflection will show that the perfect apparatus is one that carries the flow pipe in a direct vertical line to the cylinder or tank; this is never, or but rarely possible, but skill and ingenuity should be exercised to carry the pipes as nearly as possible in this direction.
The flow of steam ought not to be fast enough to prevent the water of condensation from returning freely. All the circulating pipes should be lowest at the discharge end, and the inclination given them should not be less than one foot in fifty.
Fig. 138.
Fig. 139.