Part 5 Ch. 12-15 Fire Service Pressure Calculations

Question 1

Supplying Master Streams w/ multiple lines

Answer 1

• If multiple line of different lengths but same diameter are feeding a Masterstream device from one Pumper, add all lengths of hose together and divide by the number of hoses to get a median
• If different diameters must calculate each one and flow at the highest and gate down others

Question 2

Hand or Counting Fingers Method

Answer 2

FL in 100’ of 2 ½” Hose =
Base of finger is GPM starting at thumb 100gpm to pinkie 500gpm, multiply the first digit of GPM by the Set number at the tip of finger (thumb is 2/pinkie is 10)
GPM-Thumb=100, Index=200, Middle 300, Ring= 400, Pinky = 500 , can use half numbers for GPM in between
Set Number- Thumb=2, Index= 4, Middle= 6, Ring= 8, Pinky = 10 can use half numbers in between when calculating GPM in between
FL in 100’ of 1 ¾” Hose=
Can be used by 1 ¾ ” hose the same way with different variables
GPM- Thumb=100, Index= 125, Middle= 150, Ring= 175, Pinky= 200
Set number- Thumb=1, Index= 2, Middle= 3, Ring= 4, Pinky= 5

Question 3

When using “wet water”

Answer 3

reduce final FL by 25%

Question 4

Fire Hose
Anual Service Test and Max Operating Pressures

Pre and post 1987

Answer 4

type—————-Annual——–Max
Attack————300[250]—-275[225]
Relay(3.5-5in)–200[200]—-275[185]
Relay(6+)——–200[150]—-185[135]

[ ] = pre 1987

Question 5

Considerations for Establishing Relay operation

water shuttle vs relay

Answer 5

• Water shuttles= commonly used in situations where water source is more than a mile away from the fire scene, or trucks don’t have enough supply hose to establish relay ops
• Relay pumping = Preferred method, it makes a constant supply of water, uses less fuel, as well as safer because trucks aren’t constantly driving

Question 6

NFPA 1901 Minimum required hose carried by pumpers

Answer 6

at least 800 ft of 2.5in or larger supply hose

Question 7

Types of Relay Pumping Operations-
2 methods

Max Distance Relay/Constant Pressure

Answer 7

• Max Distance Relay= Most used, determine amount of water to be flowed and space the pumpers accordingly IFSTA recommends minimum residual pressure of 20psi
  -[Relay Distance/Max Dist. for pumper(table)] + 1
  -always round up
• Constant Pressure= Determines maximum flow available from a particular setup and by using a constant pressure in the system. Each truck lay same type and length of hose and then all trucks pump at the same psi. This method requires a constant flow of water on the fireground.
  -advantages:
  -Speeds relay activation because each driver knows exactly how much hose and psi to pump
  -requires no calculations
  -minimizes radio traffic
  -operators only have to guide and adjust to one pressure
• Cavitation can be recognized by and increase in RPM not resulting in an increase in discharge pressure

Question 8

Sprinklers designed based on 2 factors

Answer 8

1. Type of Building
2. Type of occupancy to be protected

Question 9

Sprinklers: Occupancy Hazard Classifications

Answer 9

• NFPA 13 Standard for installation of sprinklers classifies:
• Light hazard:
  -low rate of heat release
• Ordinary Hazard:
  -group 1: where combustibles don’t exceed 8ft in ht
  -group 2: 12 ft in ht
• Extra-Hazard:
  -group 1: Particle-Board Manuf, Saw Mills, Textile Packing
  -group 2: contain flammable liquid spraying, Varnish Dripping, Flow Coating Operations

Question 10

Common Types of Sprinkler Systems

(Wet, Dry, Deluge, Pre-action)

Answer 10

• Wet Pipe= Most common and reliable, pipes filled with water at all times ready for activation, used in locations not subject to freezing temps or in limited size can use anti-freeze in system. Waterflow indicator activated when water flowing and activates alert alarm either locally or to monitoring center
• Dry Pipe= Used in buildings that may freeze. Maintains air under pressure in pipes, water sits below check valve, when triggered air pressure drops opening check valve and water begins flowing. Compressed air pressure can come from a compressor dedicated for the system only, or a facility wide compressed air-system. Waterflow activated alarm as well
• Deluge= Similar to dry pipe with no water but also have no sprinkler heads. Heat, Smoke, or Flame detection device installed separate of system in same area. Used in areas that require quick/large activation of water such as aircraft hangers and may have foam capabilities. Almost always supplied by a fire pump due to large quantity of water used
• Pre-action= Used in occupancies where water damage prevention is important, such as computer rooms. System has features of deluge and dry pipe systems. Pipes usually dry. Has a two-step activation system for added protection from accidental discharges

Question 11

Standpipe System Design

(Dry auto, Wet auto, Semi auto Dry, Dry manual, Wet manual)

Answer 11

• Installed in building over 4 stories tall and required by code in Hi-Rise building beyond Aerial reach
• Standpipes not acceptable substitute for Sprinkler System
• Dry Automatic SP= Similar to dry sprinklers pipes pressurized with air, can supply themselves with water and pressure without use of pumper at FDC. Down side id Large amounts of air need to be bleed off before good fire stream achieved
• Wet Automatic SP= Most common design, can provide effect water and pressure to attack lines anywhere in occupancy. Waterflow alarm signals residents and dispatch
• Semi-Automatic SP= Similar to auto but remote control activation device must be operated to supply water to system
• Dry Manual SP= No permanent water supply. System must be charged and supplied by pumper at FDC, once charge need to bleed off considerable amount of air
• Manual Wet SP= Small water source only capable of maintaining pipes filled with water. Pumper must still charge system at FDC for system to be operated. No need to bleed air

Question 12

Classifications of Standpipe Systems

Answer 12

• Class 1= 2 ½” discharges for FF, NFPA require Hi-Rise to be auto or semi auto type
• Class 2= 1 ½” hose for occupants, can be used by FF for initial or mop-op OPS with their own hose at connections. Do NOT use hose in cabinets. NFPA says must be wet system unless temp prevent
• Class 3= Both 1 & 2

Question 13

Standpipe System Components

Answer 13

• Piping
  -Must use ferrous metal, Copper, or Steel and capable of withstanding 300psi operating pressures
  -Stand-alone system must have 4” diameter, if in conjunction with Sprinklers must be 6”
• Hose Connections-
  -Connections must 2 ½” and be no less than 3’ and no more than 5’ from floor
  -Must have same threads as Fire Dept
  -Cap and chain with 1 ½” reducer if Sprinkler in system
  -Travel distance not exceed 150’ or 200’ if sprinklers in system
• Pressure Regulating Devices-
  -Required where discharge outlet exceeds 175psi for 2 ½” or 100psi for 1 ½” connections
• FDC-
  -After 450’ to FDC will be present
  -Must have raised sign that says STANPIPE and if connection does not serve all the building it must state which floors are serviced
• PIP for Standpipes-
  -System should be hydrostatically tested to 200psi for 2 hours, if system uses higher than 150psi it should be tested 50psi above its operating pressure
  -Dry systems hydrostatically tested every 5 years
  -Hose cases within 6’ of floor and have sign the says FIREHOSE
  -Dry Pipe System should have sign reading DRYSTANDPIPE for FF use only
• FF Operations at Occupancies with SP
  -Must have SOP’s
  -Hi-Rise bundle- 100-150’ hose, nozzle, reducer, spanner, chocks
  -Check all valves when going up stairwells
  NFPA 14 at no time shall standpipe be charges in excess of 200psi unless specifically designed to be operated at higher pressure