CVFD Training – Pump Operations

1. CVFD Training – Pump Operations SFFMA Training Objectives 24-01.01 – 24-01.02

2. NET ENGINE PRESSURE • Net Pump Discharge Pressure (new term) • Actual amount of pressure being produced by the pump. • When taking water from a hydrant, it is the difference between the intake pressure and the discharge pressure. • When drafting it is the total of the intake pressure and the discharge pressure.

3. NOZZLE REACTION • Counterforce directed against a person holding a nozzle or a device holding a nozzle by the velocity of water being discharged. • Measured in pounds • Nozzle reaction formulas NR= 1.57·d²·NP and NR= 0.0505·Q·NP

4. POUNDS PER SQUARE INCH(PSI) • U.S. unit for measuring pressure. • Reflected on the discharge gauge • Called Pump Discharge Pressure or Engine Pressure

5. PUMP DISCHARGE PRESSURE • ENGINE PRESSURE • Actual velocity pressure (measured in PSI) of the water as it leaves the pump and enters the hoseline.

6. VELOCITY • Speed; the rate of motion in a given direction. It is measured in feet per second for the fire service.

7. Water Hammer Water moving through a pipe or hose has both weight and velocity. The weight of water increases as the pipe or hose size increases. Suddenly stopping water moving through a hose or pipe results in an energy surge being transmitted in the opposite direction, often at many times the original pressure. This surge is called Water Hammer

8. WATER HAMMER • Force created by the rapid acceleration or deceleration of water. It generally results from closing a valve or nozzle too quickly. • Can be up to seven (7) times the original pressure.

10. GAUGES • Master Intake gauge (Compound) • Master Discharge gauge • Discharge gauge (individual gauges) • Oil Pressure • Voltmeter • Tachometer (engine RPM) • Pump overheat indicator • Engine coolant temperature gauge

11. Master Intake Gauge • Measures positive or negative pressure • Calibrated from 0 to 600 PSI (usually) for positive and from 0 to 30 inches of vacuum for negative pressure • Provides indication of residual pressure from a hydrant or relay operation • Provides indication of maximum capacity of pump when at draft

13. Master Discharge Gauge • Measures positive pressure • Calibrated from 0 to 600 PSI • Up to 1000 PSI on special pumpers • Measures pressure as it leaves the pump and before it gets to the individual gauges • Always reads the highest pressure the pump is producing

15. Discharge Gauge • Individual gauges measure the pressure for each individual discharge. • Use these gauges not the master discharge gauge when flowing any line.

16. Oil Pressure Gauge • Measures oil pressure of the motor. • Normal operating pressures vary with different brands of apparatus. • Variations from normal may indicate pending problems.

17. Voltmeter • Provides a relative indication of battery condition and alternator output by measuring the drop in voltage as some of the more demanding electrical accessories are used. • Indicates the top voltage available when the battery is fully charged. • Measures drop when electrical demand is high.

18. Tachometer • Records the engine speed in revolutions per minute (rpm) • It can give valuable information about the condition of the pump. • May refer to the acceptance test rating panel to check on pump efficiency (identification plate on the pump panel)

19. Pump Overheat Indicator • Audible or visual indicator • * Overheating occurs when the pump impeller is spinning, for prolonged periods, but no water is being discharged

20. Pump Overheat • Best place to check for overheat is right here • Best way to never overheat the pump is to always be moving water.

21. Engine Coolant • Engine coolant temperature gauge • Shows the temperature of the engine coolant - the normal operating range of the Detroit Diesel Series 60 Engine is between 192° - 205° Fahrenheit • Caution: An engine that operates too cool is not efficient. An engine that has an operating temperature that is too high may be damaged.

22. Pump Theory and Pump Equipment

23. TYPES OF FIRE PUMPS • Piston • Single, Multiple • Rotary • Gear • Centrifugal • Single-stage, Two-stage, Multiple-stage

24. Pump Equipment • Centrifugal Pump • Multi-stage Pumps • Cavitation • Pressure Relief Valves/Governors • Positive Displacement Primers • Manual Pump Shift • Gauges • Auxiliary Cooler • Valves

25. Centrifugal Pump • Components • Impeller • Eye • Hub • Vanes • Volute • Shroud • Casing

26. Pump Impeller Vane Impeller eye Shaft opening Shroud

27. Centrifugal Pump • Rated at draft • Can double its’ capacity with adequate positive pressure • Non-positive displacement pump • Not self priming • Cavitation occurs when  RPM without corresponding increase in pressure

28. Centrifugal Pump • Three factors influence pump discharge pressure (PDP): • 1) Incoming Pressure • 2) Speed of the impeller • 3) Amount of water being discharged • Single or Multi-Stage • Maximum Discharge Pressure @ 150 psi plus static pressure on hydrant

29. Rated Capacity • A pump is rated @ draft, the following show the capacity @ different pressures: • 100% @ 150 psi (net pump pressure) • 70% @ 200 psi (net pump pressure) • 50% @ 250 psi (net pump pressure)

31. Rated Capacity • When connected to a positive pressure source, the capacity of a pump can be doubled (assuming that the source is of adequate size and pressure). • The capacity of a pump can also be increased when using multiple intakes or increasing the size of the supply line.

32. Two-Stage Centrifugal Pumps • Single vs. Multi-Stage • Pressure (series) vs. Volume (parallel) • Most operations in pressure mode • 50 % rule • Change over @ 50 psi net pump pressure • Transfer valve found on pump panel, usually with indicator light

33. Two-Stage Centrifugal Pumps • The two-stage pump has two impellers mounted within a single housing. • Generally, the two impellers are identical and have the same capacity. • What gives the two-stage pump its versatility and efficiency is its capability of connecting these two stages in series for maximum pressure or in parallel for maximum volume by use of a transfer valve.

34. Two-stage Centrifugal pump • Pumping in the Volume (Parallel) Position • When the pump is in the volume position, each of the impellers takes water from a source and delivers it to the discharge.

35. Pumping in the Pressure (Series) Position • When the transfer valve is in the pressure position, all the water from the intake manifold is directed into the eye of the first impeller. • The first stage increases the pressure and discharges 50 to 70 percent of the volume through the transfer valve and into the eye of the second impeller. • The second impeller increases the pressure and delivers the water (at the higher pressure) into the pump discharge port.

37. Two-Stage Centrifugal Pumps • Each fire pump manufacturer has recommendations for when the transfer valve on their pump should be in the volume or pressure position. • The process of switching between pressure and volume is sometimes referred to as changeover.

38. Pump packing • Number of drops from packing. • Water should drip, not run from packing gland • New “Ceramic” packing • Must have temperature relief valve to protect ceramic disk

39. Cavitation What is Cavitation?

40. Cavitation • Firefighters definition: • Water is discharged from the pump faster than it is coming in. • Cavitation: • A condition in which vacuum pockets form in the pump and causes vibrations, loss of efficiency, and possible damage.

41. Cavitation • During Cavitation: • The pressure at the eye of the impeller falls below normal atmospheric pressure. • The water boils faster at temperatures less than normal atmospheric pressure. • Steam and air bubbles are created. • The air bubbles move outward in the impeller and into the high-pressure zone. • The air bubbles collapse, producing noise and vibration.

42. Cavitation • To Avoid Cavitation: • Intake pressure from pressurized sources should not drop below 20 psi. • Cavitation can be recognized by the fact that increasing the engine rpm does not result in an increase in discharge pressure.

43. TRANSFER VALVE • Only on Pressure/Volume Pumpers • Switched by: Electric switch, Pneumatic shift, Water-hydraulic, or Manual hand-wheel • Changes pump from Pressure (Series) – to Volume (Parallel) • Switched when pumping greater than 50% of the rated capacity of the pump

44. TRANSFER VALVE • This is an electric transfer switch • Other switches can be: • Pneumatic • Hydraulic • Manual

45. TRANSFER VALVE • This is a manual back-up to the transfer switch

46. POWER TRANSFER

47. POWER TRANSFER • Engine to wheels • Engine to fire pump

48. Pump drives • Mid-ship mount • Front mount • PTO • Rear mount • flywheel

49. Mid-Ship Mount • Mid-Ship mount: a split-shaft gear case located in the drive line between the transmission and the rear axle. • Unit will pump or drive, not both.

50. Power Take-Off • Power is taken off the transmission before it gets to the back wheels for “pump and roll” operation. • The PTO unit is powered by an idler gear in the truck transmission.