P-250 PORTABLE PUMP

The P-250 is a gasoline-driven portable pump with an internal-combustion engine. It is used in fire fighting and in dewatering operations. When used for fire fighting, the P-250 draws water from the sea and pumps the water through suitable hoses and nozzles at a high pressure. When used for dewatering, the P-250 draws a large volume of water from flooded compartments and discharges it into the sea. The P-250 has the capacity to pump 250 gallons of water per minute. The pump is self-priming up to a suction lift of 16 to 20 feet. Figures 5-46 and 5-47 show two different views of the P-250.

Before operating the P-250 portable pump, make sure that all of the suction hose connections between the foot valve and the pump are tight. Be sure that proper-size gaskets are used at all of the suction connections. The strainer should be completely submerged in water. If the pump fails to draw water or if the discharge nozzle shows an uneven stream, the probable cause is a poor connection allowing air leakage into the suction side. The suction screen should rest in clear water-not in mud or debris, which might be drawn into the pump. The suction hose should be supported. The foot valve should be completely submerged when the pump is operating. Otherwise, severe damage could result. The pump must not be operated in a confined space unless the exhaust hose is connected to the pump. The exhaust hose carries the toxic engine exhaust gases to the atmosphere. The gas tank is a 6-gallon tank and is identical to the tanks used for the outboard motors on small pleasure boats.

Figure 5-47.-P-25O pump, showing control panel.

To operate the P-250 pump, proceed as follows:

CAUTION

Do NOT run the pump more than 45 seconds unless pressure shows on the gauge. If the pump is not primed in 45 seconds, stop the engine, tighten all suction connections and hose couplings, and try priming again. If the pump is operated more than 15 to 20 seconds with the outlet valve in the CLOSED position, the pump may begin to cavitate and speed up as result of the accumulation of air in the impeller housing. Open the water outlet valve momentarily to allow the trapped air to escape.

1. Make the required suction and discharge connections.

2. Fill the gasoline tank with a mixture consisting of one-half pint of the specified engine oil to each gallon of gasoline. Mix the oil and the gasoline thoroughly.

3. Clamp the fuel tank to the top of the frame, using the clamps provided for this purpose.

4. Connect the hose assembly from the fuel tank to the plug provided on the control panel.

5. Pump fuel to the carburetor by pressing the push button on the tank several times, until you feel some resistance. At this point, stop pressing IMMEDIATELY. If you continue to press the push button after you have once felt resistance, you could damage the diaphragm.

6. Place the water outlet valve in the CLOSED position. Be sure that the wing nut on the manual priming filler bowl is tight.

7. Pull the choke knob to the extended position. Turn the HIGH- and the LOW-speed knobs on the control panel three-quarters of a turn to the left from the CLOSED position.

8. Pull the starting cord rapidly, but do not

jerk the cord. After the engine starts and runs for a few seconds, push the choke knob in toward the control panel. The starter cord will automatically rewind.

9. Check the pressure gauge to make sure that water pressure is building up. This should occur 20 seconds after the pump has been started, at a suction lift of 16 feet.

10. When pressure shows on the gauge, open the outlet valve slowly and allow water to enter the discharge hose.

11. Adjust the carburetor HIGH-speed dial to the best operating position. For slow speed adjustment, slow the engine to IDLE by partially closing the throttle with the stop button.

12. Adjust the water discharge pressure by turning the pressure regulator to the desired setting. Use a screwdriver to make this adjustment.

13. While the engine is running, check the water pressure to be sure that it remains at the desired level.

If you have to restart a P-250 while the engine is still warm from previous use, pull the starter cord. No choking should be necessary. However, use the choke if the engine does not start immediately. Be careful to avoid flooding the engine. If the engine does flood, close the needle valves and crank the engine until it starts. Then set the HIGH- and LOW-speed knobs to the previously set positions.

After the P-250 pump has been operated and then shut down, it should be prepared for temporary stowage as follows:

1. Remove the fuel tank from the frame and disconnect the pump. Release the tank pressure by loosening the filler cap. Retighten the cap.

2. Disconnect the suction, exhaust, discharge, and drain hoses.

3. Drain the pump and pump head by inverting the entire unit so that the flywheel end is up. Tilt the unit back and forth until all water has been drained. Repeat this operation several times, each time returning the unit to its normal position for about 10 seconds; this allows more water to drain from the power head to the impeller housing.

4. Flush the pump by pouring clean freshwater, if available, into the impeller housing through the manual priming bowl. Drain the impeller housing.

5. Replace the thread protectors on all openings, and clean and dry the entire unit.