What is Potential Energy?
What is Potential Energy?
We’ve talked about static pressure and how that can be related to a column of water.
You can use the link below to get to the earlier segments
Let’s now look at that in the context of the potential energy stored in a system.
Potential energy is defined as the energy associated with the arrangement of a system of objects that exert forces on one another.
Remember that water as a working fluid; is effectively incompressible. If the water is confined in a pipe or vessel, it can store energy; this can occur by increasing the pressure imposed on the fluid, or by elevating the water relative to an outlet as in an elevated water tank.
Both are examples of stored energy. Stored energy is potential energy.
POTENTIAL VS. KINETIC ENERGY
If that energy is released it can perform useful work. When it is released, we call that kinetic energy.
Potential energy is stored energy. Kinetic energy is energy in motion.
Well, all of that is Interesting but how does that relate to fire suppression systems?
POTENTIAL ENERGY IN FIRE SUPPRESSION
Fire suppression systems make use of potential energy in the form of system pressure to deliver water within the suppression pipe networks.
Fire suppression systems must be pressurized to convey water to an operating sprinkler. The system pressure must be maintained to ensure a continued flow of water.
The potential energy in the system (pressure) is converted to kinetic energy causing the water to move and eventually flow to the open sprinkler near a fire.
So, what sustains the flow of water?
What happens if the potential energy is drained or used up?
HOW TO “ADD” ENERGY TO THE SYSTEM?
Any fire suppression source of water must have sufficient potential energy to meet the demand flow of the suppression system for a specific / planned duration.
At minimum, the system potential energy is converted to kinetic energy to deliver water to either the hydraulically most demanding fire area, or any other point within the pipe network with an open sprinkler.
What happens then if there is not enough potential energy to supply the system?
Potential energy can be created by providing additional pressure. This can be achieved with an elevated tank, a pressure tank, or adding a fire pump.
The elevated tank creates system static pressure based on the height of the column of water.
A pressure tank uses air pressure right next to its water supply to increase the pressure of the water in the tank. The pressure isn’t created by height, like an elevated tank, but instead by air compressors that raise the pressure within the tank.
A fire pump creates higher pressure by adding energy into the water system. It’s mechanically forcing energy into the system. Fire Pumps add pressure to the system. Downstream of a fire pump, somewhere just past the discharge side of a fire pump, is a check valve. This essentially “locks” the pressure in as soon as the pump turns off. Now, even though the fire pump is not operating, that potential energy is “stored” in the pipe network.
In the context of fire suppression systems, potential energy is stored system energy. It is the sustained static pressure of the system. That energy is converted to kinetic energy as water is flowed to an open sprinkler.
The static pressure of a municipal water source, an elevated tank, or a fire pump all create system potential energy.
We talk quite a bit about storing energy by pressure. But how do we measure pressure?
Next in our series, we’ll talk about the tools we use to actually measure pressure.
I’m Ed Henderson; this is MeyerFire University.
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