0. Pumping Apparatus Driver/ Operator — Lesson 8 Customary
Pumping Apparatus Driver/Operator Handbook, 2nd Edition
Chapter 8 Customary — Theoretical Pressure Calculations

1. Pumping Apparatus Driver/Operator
Learning Objectives
1. Answer questions about friction loss, elevation pressure, and total pressure loss (TPL).
2. State the equation for determining friction loss.
3. Calculate friction loss.
4. Select facts about determining your own friction loss coefficients.
(Continued)
Pumping Apparatus Driver/Operator

2. Pumping Apparatus Driver/Operator
Learning Objectives
5. Test hose carried on your apparatus to determine friction loss.
6. Answer questions about appliance pressure loss.
7. Select facts about elevation pressure.
8. State the equations for determining elevation pressure.
(Continued)
Pumping Apparatus Driver/Operator

3. Pumping Apparatus Driver/Operator
Learning Objectives
9. Calculate elevation pressure.
10. Answer questions about hose layouts.
11. Calculate total pressure loss in single hoseline layouts.
12. Calculate total pressure loss for wyed hoselines of equal length.
(Continued)
Pumping Apparatus Driver/Operator

4. Pumping Apparatus Driver/Operator
Learning Objectives
13. Calculate total pressure loss for siamesed hoselines of equal length.
14. Calculate total pressure loss for standpipe operations.
15. Calculate total pressure loss for multiple hoselines of unequal length.
(Continued)
Pumping Apparatus Driver/Operator

5. Pumping Apparatus Driver/Operator
Learning Objectives
16. Calculate total pressure loss for wyed hoselines of unequal length and for manifold hoselines.
17. Calculate total pressure loss for master streams.
18. State the equation for determining pump discharge pressure.
(Continued)
Pumping Apparatus Driver/Operator

6. Pumping Apparatus Driver/Operator
Learning Objectives
19. Calculate pump discharge pressure.
20. State the equation for determining net pump discharge pressure (NPDP).
21. Calculate net pump discharge pressure.
Pumping Apparatus Driver/Operator

7. Friction Loss and Elevation Pressure
To produce effective fire streams, it is necessary to know the amount of friction loss in the fire hose and any pressure loss or gain due to elevation.
Causes of friction loss
Hose condition
Coupling condition
Kinks
Volume of water flowing per minute
(Continued)
Pumping Apparatus Driver/Operator

8. Friction Loss and Elevation Pressure
The calculation of friction loss must take into account the length and diameter of the hoseline and any major hose appliances attached to the line. Because the amount of hose used between an engine and the nozzle is not always the same, driver/operators must be capable of determining friction loss in any given length of hose.
(Continued)
Pumping Apparatus Driver/Operator

9. Friction Loss and Elevation Pressure
Elevation differences, such as hills, gullies, aerial devices, or multistoried buildings, create a pressure loss or gain known as elevation pressure.
Together, friction loss and elevation pressure loss are referred to as total pressure loss.
Pumping Apparatus Driver/Operator

10. Determining Friction Loss
Equation A
FL = 2Q2+Q
FL = Friction loss in psi
Q = Flow rate in hundreds of gpm (flow/100)
L = Hose length in hundreds of feet (length/100)
(Continued)
Pumping Apparatus Driver/Operator

11. Determining Friction Loss
Determine the number of hundreds of gallons of water per minute flowing (Q) through the hose by using the equation:
Q = gpm/100
Determine the number of hundreds of feet of hose (L) by using the equation:
L = feet/100
(Continued)
Pumping Apparatus Driver/Operator

12. Determining Your Own Friction Loss Coefficients
If you wish to calculate more accurate results for the fire hose that is carried on your apparatus, rather than use the results from the standard friction loss coefficients, it is recommended that you test your hose to determine the actual coefficients.
(Continued)
Pumping Apparatus Driver/Operator

13. Determining Your Own Friction Loss Coefficients
In order to get results indicative of averages that can be expected on the fireground, it is necessary to use the same hose that would be used on the fireground.
Conduct tests on hose that is in service, not on hose that has been in storage or hose that has never been put into service (unless new hose is about to be placed into service).
(Continued)
Pumping Apparatus Driver/Operator

14. Determining Your Own Friction Loss Coefficients
Departments should test only one hose type at a time.
It is important that all measuring devices are in good condition and properly calibrated.
(Continued)
Pumping Apparatus Driver/Operator

15. Determining Your Own Friction Loss Coefficients
Needed equipment
Pitot tube or flowmeter
Two in-line gauges, calibrated in increments of 5 psi or less
Hose to be tested
Smoothbore nozzle (if using pitot tube)
Any type nozzle (if using flowmeter)
(Continued)
Pumping Apparatus Driver/Operator

16. Determining Your Own Friction Loss Coefficients
Refer to Skill Sheet 8-1 Customary for detailed instructions.
Pumping Apparatus Driver/Operator

17. Appliance Pressure Loss
Appliances on the fireground include reducers, increasers, gates, wyes, manifolds, aerial apparatus, and standpipe systems.
(Continued)
Pumping Apparatus Driver/Operator

18. Appliance Pressure Loss
Appliance friction loss is insignificant when the total flow through appliances is less than 350 gpm.
For this lesson, assume a 0 psi loss for flows less than 350 gpm and a 10 psi loss for each appliance (other than master stream devices) in a hose assembly when flowing 350 gpm or more.
(Continued)
Pumping Apparatus Driver/Operator

19. Appliance Pressure Loss
Friction loss caused by handline nozzles is not considered in the calculations in this lesson, as it is generally insignificant in the overall pressure in a hose assembly.
For this lesson, assume a friction loss of 25 psi in all master stream appliances, regardless of the flow.
Pumping Apparatus Driver/Operator

20. Pumping Apparatus Driver/Operator
Elevation Pressure
Elevation pressure is created by elevation differences between the nozzle and the pump.
(Continued)
Pumping Apparatus Driver/Operator

21. Pumping Apparatus Driver/Operator
Elevation Pressure
Water exerts a pressure of psi per foot of elevation.
When a nozzle is operating at an elevation higher than the apparatus, this pressure is exerted back against the pump.
To compensate for this pressure “loss,” elevation pressure must be added to friction loss to determine total pressure loss.
(Continued)
Pumping Apparatus Driver/Operator

22. Pumping Apparatus Driver/Operator
Elevation Pressure
(Continued)
Pumping Apparatus Driver/Operator

23. Pumping Apparatus Driver/Operator
Elevation Pressure
Operating a nozzle lower than the pump results in pressure pushing against the nozzle.
This “gain” in pressure is compensated for by subtracting the elevation pressure from the total friction loss.
(Continued)
Pumping Apparatus Driver/Operator

24. Pumping Apparatus Driver/Operator
Elevation Pressure
Pumping Apparatus Driver/Operator

25. Determining Elevation Pressure
Equation B
EP = 0.5H
EP = Elevation pressure in psi
0.5 = A constant
H = Height in feet
(Continued)
Pumping Apparatus Driver/Operator

26. Determining Elevation Pressure
It is generally easier to determine elevation pressure in a multistoried building by another method. By counting the number of stories of elevation, use:
Equation C
EP = 5 psi x (number of stories)
Pumping Apparatus Driver/Operator

27. Pumping Apparatus Driver/Operator
Hose Layouts
The combination of friction loss and elevation pressure is referred to as total pressure loss.
Pressure changes are possible due to hose friction loss, appliance friction loss (when flows exceed 350 gpm), and any pressure loss or gain due to elevation.
By adding all the affecting pressure losses, the total pressure loss can be determined for any hose lay.
Pumping Apparatus Driver/Operator

28. Pumping Apparatus Driver/Operator
Simple Hose Layouts
Single hoseline
Multiple hoselines (equal length)
Wyed hoselines (equal length)
Siamesed hoselines (equal length)
Pumping Apparatus Driver/Operator

29. Pumping Apparatus Driver/Operator
Single Hoseline
Is the most commonly used hose lay
Presents the simplest friction loss calculations
Pumping Apparatus Driver/Operator

30. Multiple Hoselines (Equal Length)
When determining the friction loss in equal length multiple lines whose diameters are the same, it is only necessary to perform calculations for one line.
When the diameters of the hoselines vary, friction loss calculations must be made for each hoseline. The pump discharge pressure is then set for the highest pressure.
Pumping Apparatus Driver/Operator

31. Wyed Hoselines (Equal Length)
When using a wye, it is important that the attack lines wyed from the supply line are the same length and diameter in order to avoid two different nozzle pressures and an exceptionally difficult friction loss problem.
(Continued)
Pumping Apparatus Driver/Operator

32. Wyed Hoselines (Equal Length)
When the nozzle pressure, hose length, and diameter are the same on each wyed line, an equal split of the total water flowing occurs at the wye appliance.
This enables only one of the wyed hoselines to be considered when computing the total pressure lost.
(Continued)
Pumping Apparatus Driver/Operator

33. Wyed Hoselines (Equal Length)
Step 1 — Compute the number of hundreds of gpm flowing in each wyed hoselines by using the equation:
Q = flow rate (gpm)
100
(Continued)
Pumping Apparatus Driver/Operator

34. Wyed Hoselines (Equal Length)
Step 2 — Determine the friction loss in one of the wyed attack lines using the equation:
FL = 2Q2+Q
(Continued)
Pumping Apparatus Driver/Operator

35. Wyed Hoselines (Equal Length)
Step 3 — Compute the total number of hundreds of gpm flowing through the supply line to the wye by using the following equation:
QTotal = (gpm in attack line 1) + (gpm in attack line 2)
100
(Continued)
Pumping Apparatus Driver/Operator

36. Wyed Hoselines (Equal Length)
Step 4 — Determine the friction loss in the supply line using.
(Continued)
Pumping Apparatus Driver/Operator

37. Wyed Hoselines (Equal Length)
Step 5 — Add the friction loss from the supply line, one of the attack lines, 10 psi for the wye appliance (if the total flow exceeds 350 gpm) and elevation pressure (if applicable) to determine the total pressure loss.
Pumping Apparatus Driver/Operator

38. Siamesed Hoselines (Equal Length)
When calculating friction loss in siamesed lines, however, it is necessary to use a different set of coefficients than for single hoselines.
(Continued)
Pumping Apparatus Driver/Operator

39. Siamesed Hoselines (Equal Length)
Step 1 — Compute the total number of hundreds of gpm flowing by using the equation:
Q = gpm flowing
100
(Continued)
Pumping Apparatus Driver/Operator

40. Siamesed Hoselines (Equal Length)
Step 2 — Determine the friction loss in the attack line
Step 3 — Determine the amount of friction loss in the siamesed lines
(Continued)
Pumping Apparatus Driver/Operator

41. Siamesed Hoselines (Equal Length)
Step 4 — Add the friction loss from the siamesed lines, attack line, 10 psi for the siamese appliance (if flow is greater than 350 gpm), and elevation pressure (if applicable) to determine the total pressure loss.
Pumping Apparatus Driver/Operator

42. Pumping Apparatus Driver/Operator
Complex Hose Layouts
Standpipe operations
Multiple hoselines (unequal length)
Wyed hoselines (unequal length) and manifold hoselines
Master streams
Pumping Apparatus Driver/Operator

43. Pumping Apparatus Driver/Operator
Standpipe Operations
In most cases, fire departments have predetermined pressures that driver/operators are expected to pump into the fire department connection (FDC) of a standpipe system.
(Continued)
Pumping Apparatus Driver/Operator

44. Pumping Apparatus Driver/Operator
Standpipe Operations
These pressures are contained in the department’s SOPs, in the pre-incident plan for that particular property, or on a faceplate adjacent to the FDC.
(Continued)
Pumping Apparatus Driver/Operator

45. Pumping Apparatus Driver/Operator
Standpipe Operations
In order to be able to determine the required pressure for the standpipe system, it is necessary to determine the total pressure loss.
Treat the FDC like any other hose appliance.
Pumping Apparatus Driver/Operator

46. Multiple Hoselines (Unequal Length)
When unequal length hoselines are used, the amount of friction loss varies in each line.
For this reason, friction loss must be calculated in each hoseline.
Pumping Apparatus Driver/Operator

47. Wyed Hoselines (Unequal Length) and Manifold Hoselines
Remember that when hose lengths are unequal in length and/or diameter, the total pressure loss in the system is based on the highest pressure loss in any of the lines.
(Continued)
Pumping Apparatus Driver/Operator

48. Wyed Hoselines (Unequal Length) and Manifold Hoselines
Step 1 — Compute the number of hundreds of gpm flowing in each of the wyed hoselines by using the following equation:
Q = discharge gpm
100
Step 2 — Determine the friction loss in each of the wyed lines.
(Continued)
Pumping Apparatus Driver/Operator

49. Wyed Hoselines (Unequal Length) and Manifold Hoselines
Step 3 — Compute the total number of hundreds of gpm flowing in the supply line to the wye or manifold by adding the sum of the flows in the attack lines and dividing by 100.
(Continued)
Pumping Apparatus Driver/Operator

50. Wyed Hoselines (Unequal Length) and Manifold Hoselines
Step 4 — Determine the friction loss in the supply line
(Continued)
Pumping Apparatus Driver/Operator

51. Wyed Hoselines (Unequal Length) and Manifold Hoselines
Step 5 — Add the friction loss from the supply line, the wye or manifold appliance (if total flow is greater than 350 gpm), elevation loss, and the wyed line with the greatest amount of friction loss to determine the total pressure loss.
Pumping Apparatus Driver/Operator

52. Pumping Apparatus Driver/Operator
Master Streams
Remember to add a 25 psi pressure loss to all calculations involving master stream devices.
(Continued)
Pumping Apparatus Driver/Operator

53. Pumping Apparatus Driver/Operator
Master Streams
Determining friction loss for master streams is essentially the same as those used for other fire streams, unless unequal length or diameter hoselines are used to supply a master stream appliance.
In this situation, use an average of the hose lengths for ease of calculation.
(Continued)
Pumping Apparatus Driver/Operator

54. Pumping Apparatus Driver/Operator
Master Streams
Aerial devices with piped waterways are treated in the same manner as master stream appliances: using a friction loss of 25 psi to include the intake, internal piping and nozzle.
Pumping Apparatus Driver/Operator

55. Determining Pump Discharge Pressure
In order to deliver the necessary water flow to the fire location, the pump discharge pressure at the apparatus must be enough to overcome the sum of all pressure losses.
(Continued)
Pumping Apparatus Driver/Operator

56. Determining Pump Discharge Pressure
Equation D
PDP = NP + TPL
PDP = Pump discharge pressure in psi
NP = Nozzle pressure in psi
TPL = Total pressure loss in psi (appliance, friction, and elevation losses)
(Continued)
Pumping Apparatus Driver/Operator

57. Determining Pump Discharge Pressure
It is often important that attack lines be supplied with water at somewhere near the required nozzle pressure until the driver/operator has time to calculate the correct pump discharge pressure.
It is SOP in many departments to initially charge attack lines with fog nozzles at 100 psi and solid stream nozzles at 50 psi while setting up for the pump operation.
(Continued)
Pumping Apparatus Driver/Operator

58. Determining Pump Discharge Pressure
Supplying multiple, wyed, or manifold hoselines requires different pump discharge pressures for each attack line.
Because this is not possible, set the pump discharge pressure for the hoselines with the greatest pressure demand.
Solid stream nozzle (handline) — 50 psi
Solid stream nozzle (master stream) — 80 psi
Standard fog nozzle — 100 psi
Low-pressure fog nozzle — 50 psi or 75 psi
Pumping Apparatus Driver/Operator

59. Determining Net Pump Discharge Pressure
Centrifugal pumps are able to take advantage of incoming water pressure into the pump.
Thus, if a pumper is required to discharge 150 psi, and it has an intake pressure of 50 psi coming into the pump, the pump only needs to add 100 psi more to meet the demand. This concept is called net pump discharge pressure (NPDP).
(Continued)
Pumping Apparatus Driver/Operator

60. Determining Net Pump Discharge Pressure
NPDP takes into account all factors that contribute to the amount of work the pump must do to produce a fire stream.
When a pumper is being supplied by a hydrant or a supply line from another pumper, the NPDP is the difference between the pump discharge pressure and the incoming pressure from the hydrant.
(Continued)
Pumping Apparatus Driver/Operator

61. Determining Net Pump Discharge Pressure
Equation E
NPDPPPS = PDP – Intake reading
NPDPPPS = Net pump discharge pressure from a positive pressure source
PDP = Pump discharge pressure
Note: This equation does not apply to situations where the pumper is operating at a draft.
Pumping Apparatus Driver/Operator

62. Pumping Apparatus Driver/Operator
Summary
To fulfill the primary fireground function of supplying attack crews with an adequate volume of water at pressures that are both safe and effective, driver/operators must be able to make certain hydraulic calculations in the field.
(Continued)
Pumping Apparatus Driver/Operator

63. Pumping Apparatus Driver/Operator
Summary
To do this, they must know how to factor in losses in pressure due to friction, as well as pressure losses or gains because of elevation differences.
In addition, driver/operators must be able to calculate pump pressure required to supply multiple hoselines of varying diameters, lengths, and configurations.
Pumping Apparatus Driver/Operator

64. Pumping Apparatus Driver/Operator
Discussion Questions
1. What four things can cause friction loss?
2. What is total pressure loss (TPL)?
3. What is the equation for determining friction loss?
(Continued)
Pumping Apparatus Driver/Operator

65. Pumping Apparatus Driver/Operator
Discussion Questions
4. What are the equations for determining elevation pressure?
5. What are the four types of simple hose layouts?
6. What are the four types of complex hose layouts?
(Continued)
Pumping Apparatus Driver/Operator

66. Pumping Apparatus Driver/Operator
Discussion Questions
7. What is the equation for determining pump discharge pressure?
8. What is the equation for determining net pump discharge pressure (NPDP)?
Pumping Apparatus Driver/Operator