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Chilled Water Pump GPM Formula:
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The Chilled Water Pump GPM calculation determines the flow rate required for a chilled water system based on cooling capacity and temperature difference. It's essential for proper HVAC system design and pump selection.
The calculator uses the formula:
Where:
Explanation: The formula calculates the flow rate needed to transfer the required amount of heat based on the system's cooling capacity and the designed temperature difference.
Details: Accurate GPM calculation is crucial for proper pump selection, ensuring adequate flow for heat transfer, preventing system inefficiencies, and avoiding equipment damage from improper flow rates.
Tips: Enter cooling capacity in tons and temperature difference in °F. Both values must be positive numbers. Typical ΔT values range from 10-20°F for chilled water systems.
Q1: Why is the conversion factor 24?
A: The factor 24 comes from (12,000 BTU/hr/ton) ÷ (500 BTU/hr/gpm/°F), which simplifies to 24 gpm/ton/°F.
Q2: What is a typical ΔT for chilled water systems?
A: Most systems are designed for a ΔT of 10-12°F, though some high-efficiency systems may operate at 15-20°F.
Q3: How does flow rate affect system performance?
A: Too low flow can cause poor heat transfer and freezing risks. Too high flow increases pump energy and may cause erosion in pipes.
Q4: Can this formula be used for other fluids?
A: This specific formula is for water. Other fluids would require adjustment for different specific heat capacities.
Q5: How do I select a pump based on GPM?
A: Select a pump that can provide the calculated GPM at the required system pressure, considering pipe friction losses and equipment pressure drops.