NFPA D/O Mobile Water Supply flashcards
NFPA D/O Mobile Water Supply · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Water tender
- A mobile water supply apparatus with a large tank, a fire pump, and a fast dump valve, designed to carry water to a fireground where no pressurized source exists.
- Dump valve
- A large valve on a water tender that releases tank water rapidly into a portable tank or basin; gradual opening controls surge and splash during unloading.
- Portable water tank
- A collapsible frame tank set up at a dump site to receive tender dumps and provide a buffer from which a receiving pump draws water for the fireground.
- Jet fill
- A venturi educator system that uses a pressurized water source to load a tender tank rapidly; it requires a properly sized and clear tank vent.
- Baffle
- An internal partition in a water tank that limits liquid surge; a failed baffle concentrates momentum and worsens vehicle handling and tank stress.
- Free surface effect
- The shifting of liquid in a partially filled tank that raises the center of gravity and reduces stability, making partial loads the most hazardous condition.
- Shuttle flow formula
- Rate in gpm equals total gallons delivered divided by total cycle time in minutes, where cycle time includes fill, loaded travel, dump, and empty travel.
- Cycle time
- The total elapsed time for one tender to complete a fill, loaded trip, dump, and return trip; reducing it is the primary way to increase shuttle flow.
- Usable tank capacity
- The volume a tender can actually deliver per trip, less than nominal capacity because of residual water and safe fill limits; use it in shuttle calculations.
- Fill site officer
- The supervisor who controls tender movement at the water source, assigns fill positions, and prevents collisions and self-dispatching from the queue.
- Dump site officer
- The supervisor who manages tender spacing, traffic flow, and portable tank use at the unloading point to prevent collisions and cross-flow between tanks.
- Water supply officer
- The command staff member who manages fill and dump sites, assigns tenders, tracks cycle times, and calculates the sustained flow delivered to the incident.
- Relay pumping
- A series arrangement in which each engine boosts pressure to the next engine down the line, moving water long distances through large-diameter hose.
- Dual pumping
- Two engines draft from the same source and discharge into a common manifold or large line; pumps must be balanced to avoid cavitation or overpressurization.
- Friction loss formula
- FL equals C times Q squared times L, where C depends on hose diameter, Q is flow in hundreds of gpm, and L is hose length in hundreds of feet.
- Nozzle flow formula
- Q in gpm equals 29.7 times the square of the tip diameter in inches times the square root of nozzle pressure in psi, for a smooth bore tip.
- Engine pressure
- The pump discharge pressure needed at the engine, equal to nozzle pressure plus friction loss plus elevation change plus appliance loss.
- Elevation pressure
- A change of 0.5 psi per foot of elevation, added for rise and subtracted for drop, when calculating required pump pressure for a hose layout.
- NFA fire flow formula
- Needed gpm equals length times width divided by three, times percent involvement, times 100, for a single-story building fire.
- Drafting lift limit
- The practical vertical distance a pump can lift water, roughly 20 to 25 feet at sea level, reduced by altitude, worn pumps, and leaking suction connections.
- Tank-to-pump valve
- A valve that admits water from the apparatus tank to the pump; its operation and labeling are checked during readiness inspections and pump shift drills.
- Pump shift
- The mechanism that changes the drivetrain from road gear to pump gear; it must be tested in and out during readiness checks before the apparatus is relied upon.
- Low-air warning
- An audible and visual alert that activates at approximately 55 to 60 psi of air brake pressure, warning the driver before brake performance is lost.
- Governor cut-out
- The air compressor cutoff pressure, typically near 120 to 125 psi, with cut-in near 100 psi; abnormal values indicate an air system fault.
- Following distance
- A minimum of about four seconds in good conditions, increased with speed and load; a loaded tender needs far more stopping distance than a passenger car.
- Liquid surge
- The fore-and-aft and side-to-side movement of water in a tank during braking, acceleration, or turning, which destabilizes a heavily loaded tender.
- Due regard
- The legal standard requiring emergency vehicle operators to drive with reasonable care for others, even when using warning lights and sirens.
- Spotter
- A crew member positioned behind the apparatus to guide backing, maintaining eye contact with the driver; if contact is lost, the driver stops.
- Hard suction hose
- A rigid, non-collapsible hose used to draft water from a static source, fitted with a strainer and kept off the bottom to avoid drawing debris.
- Large-diameter hose
- Hose of 4 to 5 inches used for relay, fill, and supply lines because it carries high flow at much lower friction loss than smaller hose.
- Pressure governor
- A pump control that maintains a set discharge pressure by adjusting engine speed, protecting the relay from water hammer when downstream demand changes.
- Accountability
- The system for tracking every crew member at fill sites, dump sites, and the fireground, ensuring supervisors know who is present and where.