The S100 Series end suction fire pump provides versatility in a smaller package. With a capacity of 2000 GPM (7570 L/min), the S100 Features a dynamic yet compact design, incorporating a ductile iron body with either an aluminum transmission (C20 Series or PA Series) for midship mounting or an aluminum bearing housing for direct drive mounting (pedestal mount). This image is of the Quint being assembled at KME 350 gallon water tank Pump and plumbing have been installed The centrifugal pump is preferred by the fire protection service due to its ability to fully utilize any positive suction inlet pressure, reducing the amount of work done by the pump. For example, if the required discharge pressure is 120 PSI (8 BAR), and the inlet pressure is 45 PSI (3 BAR), the pump must only produce the difference in pressures of 75 PSI (5 BAR). This contributes to low engine and pump speeds with reduced maintenance. Decreased maintenance is aided by the fact a centrifugal pump has basically only two moving parts the impeller and the shaft. 103
Centrifugal Force A centrifugal pump operates on the principle that centrifugal force is created by a rapidly spinning disk. Figure 1-1 shows that an amount of water has been placed at the center of a disk. The disk is rotated at some speed, and the water is thrown from the center toward the outer circumference of the disk. The distance that the water travels from the center directly relates to the diameter of the disk and the speed of rotation. When water is confined in a closed container (such as the pump body), its pressure rises to a level that depends on the speed of rotation. There are three interrelated factors that regulate the performance of a centrifugal pump: Waterous S100 is a Single Stage Centrifugal Pump Overheating If the pump runs even for a few minutes completely closed it may heat the water enough to scald someone when the valve is opened. When operating the pump, at least one discharge valve should be open slightly to prevent the pump from overheating. Overheating can damage the packing, seals and other pump parts. SPEED (RPM). If the speed of rotation increases with flow held constant, the water pressure increases. PRESSURE. Pressure is usually measured in Pounds Per Square Inch (PSI) (BAR). If pressure changes with speed held constant, the flow (measured in GPM) (LPM) will change inversely, that is, if pressure increases, flow decreases. FLOW. Flow is usually measured in the number of gallons of water per minute (GPM) (LPM) that a pump can deliver when supplied from draft. If the pressure is held constant, the flow will increase with an increase in the speed of rotation. 104
Impeller The impeller provides velocity to the water. This part is mounted on a shaft that is rotated by the drive. Water enters the rotating impeller at the intake (or eye), and is confined by the shrouds and the vanes mounted in the impeller to build pressure. The vanes guide water from the inlet to the discharge and reduce the turbulence of the spinning water. Vanes curve away from the direction of rotation so water moves toward the outer edge. The shrouds form the sides of the impeller, and keep the water confined to centrifugal acceleration. Single stage impeller Centrifugal Force From a Rotating Disk This image is of the Waterous S100 main pump when installed on the Quint at KME Pump transmission The figure below traces a drop of water from the intake of the impeller to the discharge outlet. The impeller is mounted so that the discharging tube is widest at the pump outlet. The increasing discharge path, known as the volute, collects the water at a constant velocity. A further increase in pressure and a decrease in velocity take place in the diffuser. 105
Cavitation occurs when a centrifugal pump is attempting to discharge more water than it is receiving. When cavitation occurs, a vacuum is created near the eye of the impeller. As the vacuum increases, the boiling point of the water is lowered until it reaches a point near the impeller eye where it flashes into vapor and enters the impeller. Once the vapor pockets, or bubbles, enter the impeller, the process begins to reverse itself. As the vapor reaches the discharge side of the pump, it is subjected to a high positive pressure, which condenses the vapor back to a liquid. The sudden change from vapor pockets to a liquid generates a shock effect which causes a significant noise that is characteristic of cavitation. This shock damages the impeller and pump housing. This may happen while pumping from draft or a hydrant. The problem in either case is the pump running away from the supply and this causes a vacuum to occur. Signs of Cavitation 1. Sudden pressure or capacity loss. 2. Increasing pump speed without corresponding increase in volume or pressure. 3. Excessive pump vibration. 4. A rattling sound resembling gravel going through the pump. Reducing pump speed or improving intake conditions will usually eliminate cavitation. Cavitation is often referred to as the pump running away from the water supply. This means that the operator is trying to pump more water out of the pump than is going into the pump. To eliminate cavitation, the operator must be aware of the warning signs and correct the situation, or serious damage to the pump and impeller will occur. The most reliable indication that a pump is approaching cavitation is when an increase in engine RPM does not cause an increase in the pump discharge pressure. The operator must not depend entirely on the vacuum gage to indicate when a pump is nearing cavitation. This is because the vacuum gage is usually tapped into the intake chamber several inches away from the leading edge of the impeller eye where the greatest amount of vacuum occurs. The most common way to eliminate cavitation is to decrease the amount of water being discharged. This is accomplished by decreasing engine speed or closing discharge valves. This will allow pressure to increase but this will result in a reduction of flow. 106
The Waterous C20 transmission, with a high-strength aluminum case, transmits power from the truck's automatic transmission either to the fire pump or to the drive axle of the truck. This image is of the Waterous S100 main pump when installed on the Quint at KME Single Stage Impeller Waterous C20 Pump Transmission After the wheels the Main Pump is installed on the chassis and then the engine and driveline. Connection of Propeller Shaft (Driveline) Pump Pump Transmission Vehicle propeller shafts connected to pump transmission 107
Low or excessive lubrication fluid may cause damage. Lubrication fluid temperature should not exceed 250 degrees F for extended periods of time. If lubricant fluid level is low, locate source of leak and repair. If level is high, loosen oil level plug and drain until proper level is reached. If any water drains out, change lubrication fluid and determine source of water leakage and repair. Premature seal wear and damage will occur. 1. Check the lubrication fluid level monthly by checking the sight plug or by removing the oil level plug. The fluid should be level with the bottom of the oil level hole. 2. Change lubrication fluid and clean breather once a year or after each 100 hours of operation, whichever comes first. Lubrication fluid may be added through the oil level hole or by removing the breather and adding fluid through the opening. Any type of automatic transmission fluid (ATF) may be used. 3. Quantities of lubrication fluid if system is completely drained and refilled: C20 Transmissions: Approximately 8 quarts of ATF. Pump Transmission: The bearings and drive chain are lubricated by a splash and passive lubrication system. Lubrication is accomplished when spray from the chain collects in a reservoir in the top of the case. The lubricant flows out of the reservoir, through a hose and onto the inside surface of the chain. This ensures all pivoting components of the chain receive lubrication. An electronic tachometer connection protrudes from the tachometer housing at a 45 angle. This tachometer pick-up senses the drive shaft speed. 108
Engaging the Pump Transmission Pump Transmission cut away Shift fork has moved to the Pump Transmission side Road Gear Position The shift mechanism within the transmission consists of a sliding internally-toothed collar which is always in engagement with an externally-toothed section of the drive shaft. A fork shifts the collar either to engage it with teeth on the drive sprocket hub (PUMP) or to engage it with the teeth on the coupling shaft (ROAD). When in PUMP position, the shift collar transmits power from the drive shaft through the drive sprocket and the chain to the driven sprocket. The coupling shaft remains stationary. When in ROAD position, the shift collar transmits power directly from the drive shaft through the coupling shaft to the truck propeller shaft and drive axle(s). In this position, the pump drive and driven sprockets remain stationary while the drive shaft rotates. Three shift indicator lights are furnished. Two are mounted in the cab and the other is mounted on the operators panel. These lights indicate to the operators that the shift has been completed into PUMP position and the truck transmission is in pumping gear. 109
Manual Pump Transmission Shift Pump Pump Shaft Pump Gear Intermediate Gear Gearbox Tachometer Cable Connection Sliding Gear Input Shaft Shift Shaft Pull the shift shaft Out for Pump Position (after in-cab control valve selection), or push shift shaft for Road Position (after incab control valve selection). Shift Fork DO NOT ATTEMPT EMERGENCY SHIFT PROCEDURES WHILE THE ENGINE IS RUNNING. Employ manual override procedure at the shift cylinder on the pump gearbox as follows: An eyebolt is provided in the shift shaft to accept a drift punch or screwdriver. By inserting this tool into the hole provided, it will enable you to pull or push the shaft manually. Pull the shift shaft Out for Pump Position (after in-cab control valve selection), or push shift shaft for Road Position (after in-cab control valve selection). If the shift stroke cannot be completed manually, turn the driveshaft slightly by hand to realign the internal gears and repeat the manual shift effort. 110