Fig. 568.
The Mason elevator pump pressure regulator. This regulator, illustrated in Fig. [569], is designed for use in connection with the larger sizes of steam pumps operating hydraulic elevators. Its important feature is in operating on the slightest change of pressure opening to its fullest extent and closing the steam valve promptly and positively.
Referring to sectional view, Fig. [570], the operation of this valve is as follows: steam from the boiler enters the regulator at the inlet, indicated by the arrows and passes through into the pump, which continues in motion until the required water pressure is obtained in the system, and through a 1⁄4-inch pipe connected to, A, acts upon the diaphragm, B. This diaphragm is raised by the excess water pressure, and carries with it the weighted lever, F, opens the auxiliary valve, D, and admits the water pressure from the connection, E, to the top of the piston, at the same time opens the exhaust ports under the piston, and allows the water under the piston to escape into the drip pipe, thereby pushing the piston down, closes the steam valve and stops the pump.
Fig. 569.
As soon as the pressure in the system is slightly reduced, the lever, F, on account of this reduced pressure under the diaphragm, is forced down by the weight, carries with it the auxiliary valve, D, opens the exhaust to the top of the piston, and also admits water pressure under the piston, which is forced up and opens the steam valve, and starts the pump.
The speed controlling device of the style A governor shown in Fig. [571] is simple and can be so set as to prevent the pump from racing, regardless of the drop in water pressure. Surrounding the upper end of the valve stem is a coiled spring, which acts as a cushion for the valve and stem, and by the use of a spring, the stem can be quite small thus reducing the friction in the stuffing-box to a minimum. The tension of this spring is sufficient to firmly seat the valve, but if excessive pressure is exerted on the piston, which is often the case when two or more pumps are connected to the same mains, the spring will be compressed and will allow the sleeve to slide down on the stem, thus relieving the valve of the increased strain, which would be liable to injure it or buckle the stem.
