How to Read a Pump Curve
Water pumped downhill takes less. PDP (Pump Discharge Pressure)- The pressure set at the fire engine in order to get the optimal pressure for a specific nozzle. NP (Nozzle Pressure)- In this example, assumed combination nozzles have a 20gpm output. H (head)- The number of feet elevation gain/loss divided by 2 = PSI gain or drop. Aug 10, †∑ The pressure at the discharge of the pump, however, will be higher for the heavier solution. Thatís why we would not be able to do simply looking at a pressure gauge and figure out what is pumpís discharge head ability is. Hopefully this post reveal some light on the difference between head and pressure.
Fire Engine Pump Discharge Pressure PDP is the pressure set at the pump to achieve the desired pressure at the nozzle furthest from the pump while considering the change in elevation and friction loss. Having a good understanding of pump discharge pressure is essential to becoming an effective fire engine operator. Learning these principals will help you with much more than calculating the correct pressure at the nozzle.
Understanding Pump Discharge Pressure will also help you gain a big picture understanding of fireline safety and hydrodynamics fluids in motion. In our example we will use a wildland firefighting example.
All the calculations work the same for structure fires, vehicle fires and wildfires. Your crew has just deployed 3 Hose Packs on a small brush fire. Assume that all nozzles are flowing at 20 GPM and the fire is burning pressre a how to define personal values hill 40 feet above the fire engine.
Objective: Determine the proper Pump Discharge Pressure for nozzle with dischargd highest friction loss. Most combination nozzles are rated at psi. Use psi for this problem. Use the picture to determine the GPM passing through each section of hose, enter it beside each section of hoseand underline that number. Step 5 - Calculate the friction loss for each hose Use a Friction Loss Calculator to determine the Friction loss for each section of hose.
Enter the friction loss calculation to the rind each hose's GPM. We have provided a small Friction Loss Cheat Sheet or compare friction loss calculators. Find the path from the fire engine to the nozzle with the highest friction loss. Circle each of the PSI friction loss values for every hose in that path. Add up those values Each organization has their own procedures for determining Friction Loss.
I am not going to tell you what is right or wrong on this example. Ask your trainer or supervisor how they want you calculate hardware friction loss. Keep in mind, hose-lay hardware usually accounts for a very small percentage of friction how to find discharge pressure of a pump on a hose-lay and no two types of hardware have how to celebrate easter at work same friction loss.
Many organizations chose to leave hardware out x the Pump Discharge Pressure calculations which is easiest. You can learn more about Hardware Friction Loss. Determine the elevation gain or loss in feet for the last nozzle in the selected circled path If there is a gain in elevation, multiply by 0.
Enter But, the user takes full responsibility for the information contained above. Use at your own risk! Fire Engine Academy.
May 26, †∑ To determine this, the total GPM must be known first. GPM is generally determined by Nozzle Tip Size. Once the GPM is determined, then Friction Loss can be calculated for that GPM and the size of the fire hose that will be used. Device pressures must also be added to the Pump Discharge Pressure for each line. Feb 09, †∑ A pumpís discharge pressure is influenced, but not determined, by other aspects of the pump. While this term is independent of other descriptions for a pump, the overall combination of flow rate, suction pressure and capacity will determine the total power of the system. A pumpís discharge pressure is actually the last step of the system. CALCULATE THE PRESSURE HEAD ANYWHERE ON THE DISCHARGE SIDE OF THE PUMP Equation  is the result of an energy balance between points 1 and 2. The same process of making an energy balance can be applied between any two points for example points 1 and X (see Figure 3). We can do an energy balance between points 1.
Discharge pressure describes the pressure of a liquid as it leaves a pump. Higher discharge pressures equal greater force behind the release while lower pressure means less.
While this term is independent of other descriptions for a pump, the overall combination of flow rate, suction pressure and capacity will determine the total power of the system.
Most pumps begin with suction, or suction pressure. This describes how much liquid the pump can pull in at any given time.
Since most pumps are designed for circumstances with plenty of material to move, this part of the system is often not much of a factor. The only common place where it comes into usefulness is when the pump needs to pull material against gravity or another basic force. The next main part of a pumping system is flow rate. This factor describes how much material can flow through the pump at any given moment. The flow rate is directly influenced by how much material comes in, suction, and how much material goes out, discharge.
The flow rate can describe the amount of material that will move over longer periods, where the other factors are generally more immediate. Capacity is a measurement of how much liquid the pump can hold at a time. In some pumps, this is simply the amount from the input to output of the system. Other types of pumps will essentially store material within the system to create additional pressure and improve discharge.
The final step in a pump system is discharge pressure. This pressure is influenced by the amount of material in the system; if the system is low on material, the pressure will likely be lower, but the majority of the value is independent. The strength of the motor within the pump determines the strength ó stronger motors create higher pressures.
The shape of the nozzle is the final factor; narrow and constricted nozzles create higher pressure than wide or open ones. It is common to describe discharge pressure in terms of vertical feet. This means that if the pump were operating under optimal conditions, the output would shoot straight up for a set number of feet; the higher the discharge pressure, the greater the number.
The also makes it simple to determine the pressure at other angles; for instance, it is increased by 50 percent when on its side and percent when pointing down. Please enter the following code:. Login: Forgot password?