To provide an additional cooling agent a water bleeder valve is also used. The water drips, as is customary, into the air pas sage and, being blown into the cylinder, assists in reducing the temperature.
The one objection to the usd of steam is the tendency for it to pass into the crankcase when a suction pressure exists there, thus partially destroying the compressor efficiency.
The arrangement for the vertical engines is somewhat different. The float box is so located that the water level in the jacket is several inches below the top of the cylinder head. The .conse quence is that on full load the head runs abnormally hot. In many installations of vertical engines the operator has abandoned the boiler idea and used a standard circulating water system, depending on the water jet for internal cooling in preference to the steam. To do this, the float box and steam dome are removed. The entrance to the air passage from the dome, as well as the con nection into the jacket for the water line from the float box, is plugged up. The water is put into the jacket through passages at the bottom which are ordinarily plugged and are used for cleaning purposes. The water discharge line is connected to the opening that previously ran to the steam dome.
With water carrying mineral salts the float valve tends to scale, destroying its regulating powers. To remove the scale is absolutely necessary; a muriatic acid solution left in the float box for a couple of hours will eliminate this deposit.
Muncie Oil Engine Water Injection.—In all sizes of Muncie engines the standard water injection system consists of a bleeder valve between the jacket and the air passage, as outlined in Fig. 251.
Muncie Automatic Water Pump.—In the larger sizes the Muncie Co. is now supplying a water pump that is incorporated in the design of the fuel injection pump. By this arrangement the amount of water injected into the cylinder is under control of the governor. Figure 329 shows their latest automatic water pump, the lower pump being that used for the water. The eccentric rod B on the return stroke of the fuel pump strikes the lever A, which in turn gives a stroke to the water pump plunger C. As the lever A forces the water plunger inward, injecting a charge of water into the engine cylinder, it engages the by-pass valve stem D. The opening of this by-pass valve relieves the
water discharge line, the flow of water to the injection valve then ceasing. The lug E allows an adjustment of the timing of the by-pass valve, in this way regulating the amount of water which enters the cylinder for a given movement of the governor eccen tric rod. When heavy oil is used but little water is necessary, consequently the adjusting nut is screwed inward on the valve stem. This causes the valve to open practically as soon as the water plunger moves. If the oil is light, more water is necessary so the by-pass valve is allowed to remain closed until the water plunger has completed the major portion of its stroke. It will be observed that the adjustment of the by-pass valve allows the necessary water to be used for any certain oil, while the governor itself regulates the quantity admitted on the various load charges. It is of frequent occurrence that the engine operates better when the water is injected at some fixed point. The lug screw F can be adjusted so that the water will enter the cylinder at any point between the point of exhaust port opening and exhaust port closure. When heavy oil is used, early water injection produces a good scavenging effect. With light oil, inclined to preignition, early water admission allows most of the water vapor to blow out the exhaust, consequently the cooling effect on the cylinder is slight. With such oils late water injection serves to keep most of the water in the cylinder, thereby providing an effective cooling medium.
Primm Oil Engine Water Injection.—The Power Manufacturing Co. makes use of a valve A, Fig. 330, which is controlled by the governor. The valve, itself, consists of a disk with a series of holes registering with like openings in the valve body. The valve stem is linked to the fuel pump plunger B, and the degree of valve opening is dependent on the length of the pump plunger stroke. The actual quantity of water passing through the valve at maxi mum valve opening can be regulated by means of the globe valve shown. In later models the Primm water valve is supplied with a regulating needle valve in place of the globe valve C.