October 8th, 2018
The way to size a jockey pump for any fire pump system is the same no matter who the manufacturer is– Aurora or Peerless or Patterson, etc. It does not matter who the makes it, the method of sizing the pump is the same. This applies to all systems. For some reason some engineers believe that the larger the system the larger the jockey pump will need to be.
However, it is important to remember that the manner in which you size the jockey pump remains the same. Simply stated sizing is 1% of the fire pump’s flow and 110 % of the fire pump’s head. For example, if the Aurora Fire Pump System which is selected is rated 500 gallons per minute at 100 psi, the jockey pump needs to handle 5 gallons per minute at 110 psi. You can go slightly over or under this formula depending on what your exact pump curve can do. I would not do any less than 4 gallons per minute and I wouldn’t go any higher than 7 gallons a minute. The main reason is that you do not want the jockey pump fighting the fire; you want the fire pump fighting the fire.
When it comes to pressure, the jockey pump needs to be able to do 10% higher than the fire pump. Adjustment of the Aurora Fire Pump System to set up permanent operation is very simple. You run the fire pump at full speed with your suction pressure. So if the fire pump is rated 100 psi typically when it is running at shut off, meaning no water is being flowed, you might be 10% or 15% higher than that; this is called “no flow pressure,” the pressure when the pump is not flowing water. Let’s say for this example suction pressure is 40 pounds and the pump’s rated maximum pressure is 110 psi. When you run the fire pump at full speed, the discharge pressure will be 150 psi. That is the pressure where you want your jockey pump to stop. The Aurora jockey pump should start 10 pounds less than that number. Again this does not just apply to the Aurora Fire Pump line. It applies to every fire pump on the market. If the maximum rated pressure of the fire pump is 110 pounds and you have 40 pounds coming in from the street, churn pressure is 150 pounds. The jockey pump stops at 150 and starts at 140. You try to have the fire pump start 10 pound less which would be 130. Typically, you would program a stop pressure. It does not mean the fire pump is going to stop at that pressure; rather it means if the pressure is above that number the stop button will work. So in this example, the jockey pump stops at 150 psi, starts at 140 psi, the fire pump starts at 130 and at pressures over 131 the stop button will work. That is how you size and program an Aurora Fire Pump System with jockey pump.