Pump Manual - Pump Discharge Pressure + Special Pumping Scenarios Flashcards
Wyed lines with equal length, diameter and GPM
- Add GPM for all nozzles and use as Q for calc’ing FL in supply line
* 2. If total GPM >350, add 10 psi FL for wye appliance* - Calc FL in supply line
- Calc FL for one discharge
- Calc PDP by adding FL for supply and one discharge
Wyed lines with unequal length, diameter, GPM flow
Same as equal length/diameter, flow, except:
Figure PDP by adding FL for supply + highest pressure handline….gate down lower pressure handline at the wye
PDP for spinklers
GPM = 0.5 x P + 15 P = sprinkler head pressure (typically 7-10 PSI)
Each open sprinkler head requires 20 GPM
Starting pressure should be 150 psi
How many sprinklers can a 1750 gpm pumper supply @ 150 GPM?
88 heads
Three types of standpipes
Class 1: 2 1/2” outlets for firefighting
Class 2: 1 1/2” hose outlets for occupant use
Class 3: Combination standpipe, integrates class 1 and class 2
Appliance friction loss in master stream appliances
25 psi
…if over 350 gpm, which master streams are by definition
Starting pressure at base of L31
200 psi
Appliance friction loss when pumping an aerial lader
25 psi for waterway piping
+
25 psi for master stream appliance
Constant pressure (“open”) relay
All pumpers in relay set the same discharge pressure, attack engine leaves an unused discharge port or waste line “open” to handle access water
Maximum Distance Relay
determines how far a pre-determined amount of water can be pumped through a particular hose size
Max distance means maximizing the distance between pumpers in the relay
Minimum intake residual pressure
20 psi
Maximum net PDP
180 PSI
= 250 PSI pump rating - 50 PSI safety - 20 PSI intake residual = 180 PSI
Estimating needed fire flow (NFF) in a relay
NFF = ( L x W x % involvement ) / 3
Calculating max distance between pumpers in a relay
Max distance = (165 / FL ) x 100
FL is for 100 ft section
165 and 100 are constants
Calculate # of pumpers needed in a relay
= ( Total distance of relay / Max distance ) + 1
How much 5” LDH does an engine carry?
900’
NFPA standard for max dependable flow for a relay pumper
75% of its rated capacity at draft
Types of positive displacement pumps
Rotary vane
Rotary gear
They pump water and air out of the centrifugal pump which creates the partial vacuum necessary to draft water
For every 1,000 ft increase in elevation, what happens when drafting?
For every 1000 ft increase in elevation,
- 0.5 psi decrease in atmospheric pressure
- loss of 1 ft in suction or lift in a fire pump
Formula for determining lift in a draft: If inches of mercury are known…
Height of lift = 1.13 x (inches of mg)
Formula for determining lift in a draft: If height of lift is known…
Inches mg = .885 x height of lift
Types of foam systems on our apparatuses
CAFS
Foam Pro
Husky
Perce Quantum system
Generally we carry 40 gallons of Class A or Novacool; some engines carry three 5 gal buckets of AFFF for class B
Class A Foam mechanism of action
It attracts carbon
It decreases surface tension of water
Raises moisture content of wood up to 50%
Absorbs 3x the BTUs compared to water alone
Class B Foam Mechanism of action
Repels carbon
Forms a film that hovers over a spill
Prevents vapor production and ignition
