For duplex pumps up to 2-inch steam pipe, inclusive, this governor is fitted with a duplex valve, which prevents the escape of oil from the pressure chamber through the orifice, _C_, and thereby prevents the steam valve from opening wide during the momentary pause of the pump piston.
This governor should be placed on the pump at some point where the requisite motion can be obtained for operating it, and also in such a way that a rod can be run from the knuckle joint on the top lever, _I_, to the valve in the steam pipe, as shown in the engraving. Place the valve in the pipe, so that the stem shall be in a direct line with the knuckle joint on the lever, and pull out the valve stem to its full extent. With the ball on the governor in its lowest position, connect the valve rod to the lever. The governor is then ready to be filled with oil. Remove the plug on top of the gauge glass, and fill the governor about half full with a good, clean, light grade of mineral oil. The governor is then ready to work.
Start the pump at about its maximum speed; place the key in the keyhole on the side of the governor and turn to the right until the speed of the pump has diminished slightly. Open the throttle valve wide, and the pump will be under full control of the governor. Should there be much dancing or fluctuation of the ball, remove the screw, _T_, insert a small screwdriver, and screw the adjusting screw in, at _K_, until the irregular motion ceases. After the governor has run a little while, it will be found that the oil in the glass gauge has dropped considerably. It should then be refilled, so that the glass will be about half full when the governor is at work. Under no circumstances should the gauge be full, as too much oil will prevent the ball from coming down and opening the valve when the steam pressure falls. As there is no glass pressure upon the glass gauge the governor may be filled while in motion by removing the plug on the top of the gauge.
_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.