1. What is Pump Discharge Pressure?

Pump Discharge Pressure (PDP) is the pressure required at the fire pump to deliver adequate water flow and pressure through hose lines to firefighting nozzles. It accounts for nozzle pressure, friction loss in hoses, elevation changes, and hose positioning above ground level.

2. How Does the Calculator Work?

The calculator uses the Pump Discharge Pressure formula:

Where:

• \( PDP \) — Pump Discharge Pressure (psi)
• \( NP \) — Nozzle Pressure (psi), typically 50 psi for standard firefighting operations
• \( FL \) — Total Friction Loss (psi) = (Friction Loss per 100ft × Hose Length) / 100
• \( ED \) — Elevation Difference (ft)
• \( HD \) — Hose Above Ground (ft)
• \( 0.433 \) — Conversion factor from feet of head to psi

Explanation: The formula calculates the total pressure required at the pump to overcome all resistance and deliver proper pressure at the nozzle.

3. Importance of PDP Calculation

Details: Accurate PDP calculation is crucial for effective firefighting operations. It ensures adequate water delivery to extinguish fires while preventing pump overload or insufficient water pressure that could compromise firefighting effectiveness.

4. Using the Calculator

Tips: Enter nozzle pressure in psi (typically 50 psi), friction loss per 100ft in psi/100ft, hose length in feet, elevation difference in feet, and hose above ground height in feet. All values must be non-negative.

5. Frequently Asked Questions (FAQ)

Q1: What is the standard nozzle pressure for firefighting?
A: Standard nozzle pressure is typically 50 psi for most firefighting handlines and master stream devices.

Q2: How do I determine friction loss values?
A: Friction loss depends on hose diameter, flow rate, and hose material. Consult fire service hydraulics manuals or manufacturer specifications for specific values.

Q3: Why is the 0.433 conversion factor used?
A: 0.433 converts feet of water head to pounds per square inch (psi), since 1 foot of water head = 0.433 psi.

Q4: When should elevation difference be considered?
A: Elevation difference is critical when pumping uphill (add pressure) or downhill (may reduce required pressure). Significant elevation changes greatly affect pump requirements.

Q5: Can this calculator be used for all fire hose types?
A: This calculator provides general calculations. Specific hose types and conditions may require adjustments based on manufacturer recommendations and local fire service protocols.