Justification VFD over Jockey Pump
In a fire pump system, a "jockey pump" is a small pump that constantly maintains water pressure
within the system by running at a low flow rate, while a "VFD" (Variable Frequency Drive) is a
device that controls the speed of the main fire pump motor, allowing it to adjust its water flow
based on pressure needs, essentially eliminating the need for a separate jockey pump in some
situations; the key difference is that a jockey pump is a dedicated small pump for pressure
maintenance, while a VFD regulates the speed of the larger fire pump to achieve pressure
control.
Key points about Jockey Pumps:
Function: Primarily used to maintain system pressure by compensating for small leaks in
the sprinkler system, preventing unnecessary cycling of the main fire pump.
Size: Smaller and less powerful than a fire pump.
Operation: Runs continuously at a low flow rate, monitored by pressure switches to
activate when pressure drops below a set point.
Key points about VFDs:
Function:
Controls the speed of the fire pump motor by adjusting the electrical frequency,
allowing for variable water flow based on pressure demands.
Benefit:
Can eliminate the need for a separate jockey pump by dynamically adjusting the
fire pump speed to maintain pressure.
Application:
Can be used with larger fire pumps to optimize their operation and reduce energy
consumption.
Benefit of using a VFD instead of a jockey pump:
• Energy Efficiency:
VFDs can significantly reduce energy consumption by only running the fire pump at the required
speed, making it a more energy-efficient option.
• System Simplification:
In some cases, a VFD can eliminate the need for a separate jockey pump, reducing system
complexity and potential failure points.