In the context of pumps, “head” is a term used to describe pressure, and it is typically represented on the vertical axis of pump charts. Although it might seem unusual to measure pressure in feet or meters, this is because pump manufacturers focus on how high their pumps can move a liquid, rather than the specific pressure, which varies depending on the liquid’s properties. For instance, a pump capable of providing 125 feet of head will generate different pressures when pumping water versus milk due to their distinct characteristics.
Knowing the head pressure is crucial because pumps are often used to transport liquids to higher elevations. As liquids move through pipes and fittings, frictional forces oppose the flow, leading to pressure losses and energy wastage. The extent of this friction depends on the liquid’s nature and the materials used in the system. Therefore, it is essential to calculate the friction or pressure loss and ensure the selected pump can overcome these challenges to maintain efficient liquid flow.
Pump charts display a range of pumps with varying head and flow rates. In smaller systems, such as domestic heating setups with minimal fittings and short pipes, a pump with lower head pressure suffices. Conversely, larger commercial systems with extensive piping and multiple components require pumps with higher head pressure to compensate for greater pressure drops.
Each pump type has a unique chart, with the vertical y-axis representing head pressure and the horizontal x-axis indicating flow rate. Essentially, head corresponds to pressure, while flow rate measures the volume of liquid the pump can move.
Imagine turning a pump sideways and connecting it to a pipe. In this position, the pump pushes liquid horizontally, achieving maximum flow rate with no pressure. As the pump is gradually rotated to a vertical position, the flow rate decreases while pressure increases, as the pump works against the liquid and friction. At the vertical position, the pump reaches maximum pressure with no flow, as it uses all its energy to hold the liquid at the highest point in the pipe. This scenario is not ideal for pump operation, as it can cause damage over time.
Flow rate quantifies the volume of liquid moving from the pump within a specific time frame, expressed in units such as gallons per minute, liters per second, or cubic meters per hour. For example, a system might be designed to transfer 2 liters of water per second from a holding tank to a process tank.
For further learning, explore additional resources and videos available online. Stay connected through social media platforms like Facebook, Twitter, and LinkedIn, and visit educational websites for more insights.
Analyze a series of pump charts provided in a digital format. Identify different pumps and their corresponding head pressures and flow rates. Discuss with your peers how these charts can be used to select the appropriate pump for various applications.
Work in groups to calculate friction losses in a hypothetical piping system. Use different liquids and pipe materials to see how these factors affect the overall head pressure required. Present your findings to the class.
Utilize simulation software to model a pump system. Experiment with adjusting the pump’s orientation and observe changes in flow rate and head pressure. Discuss the implications of these changes on system efficiency and pump longevity.
Visit a local water treatment or industrial facility to observe real-world pump systems in action. Pay attention to how head pressure and flow rate are managed in large-scale operations. Prepare a report on your observations and insights.
Conduct an experiment to measure the flow rate of a small pump. Use different liquids and measure the time taken to fill a container. Calculate the flow rate and discuss how it compares to theoretical values and the impact of liquid properties.
Here’s a sanitized version of the provided YouTube transcript:
—
The head is shown on the vertical axis, and this refers to pressure. We often hear the term “head pressure.” We measure head in feet or meters, which may seem incorrect considering we’re discussing pressure, especially since pressure gauges on pumps typically read in PSI or bar. The reason we use feet or meters is that pump manufacturers only know how high their pump can push a liquid; they do not know which liquid your system will be pumping. Each liquid has different properties, so the pressure will vary depending on the liquid used. However, the height that the pump can move the liquid will remain the same.
For example, we have a pump that can provide 125 feet of head. If we use it to pump water, the pressure will be around 54.2 PSI. But if we were to use it to pump milk, then the pressure will be around 56.15 PSI, purely because of the properties of the two fluids.
Conversion between feet and meters of head is very easy, and we have a free calculator for that, which you can find linked in the video description below.
Why do we need to know head pressure? Pumps are usually used to move liquid to a higher elevation, so we need to ensure the pump can reach this height. As we pump liquid through pipes and fittings, friction will oppose the flow. This occurs from the walls of the pipe and disturbances to the flow path, causing pressure losses that waste energy from the pump. The amount of friction depends on the liquid type and the materials used. Therefore, we must calculate how much friction or pressure loss our system will generate and ensure that the pump we select can overcome this; otherwise, we won’t get any liquid out.
When we look at pump charts, we find pumps ranging in head and flow rate. For example, in a small domestic heating system with few fittings and short pipes, we would use a pump with relatively low head pressure. However, in a commercial heating system with multiple air handling units, fan coils, and long pipe lengths, the pressure drop will be much higher, so we would need a pump that can provide much more head pressure.
Each type of pump has a different chart, and the data plotted on them varies with the model. The first thing we notice is that on the main vertical y-axis, we have the head pressure, and on the horizontal x-axis, we have the flow rate. Essentially, head is pressure, and flow rate is how much water the pump can move.
What do these charts represent? If we turn the pump sideways and connect it to a pipe, the pump is pushing the liquid horizontally, so there is no pressure, but the water is flowing at its maximum flow rate. As we slowly rotate the pump towards the vertical position, we see the flow rate decrease while the pressure increases. This is because it is now pushing against the water and the friction. When we reach the vertical position, there is zero water flowing out of the pump but maximum pressure, as it uses all its energy to push against the water and hold it as high as possible within the pipe. At this point, it’s just circulating the same bit of water, which isn’t good for the pump, so you don’t want to run a pump like this in practice.
By recording the values during the elevation, we essentially get our pump curve. However, I will note that pump manufacturers don’t test pumps this way because it’s not practical.
The flow rate is a measurement of how much liquid is flowing from the pump in a given amount of time. This measurement comes in various units, such as gallons per minute, liters per second, or cubic meters per hour. For example, a system might be designed to move 2 liters of water per second from a holding tank to a process tank.
That’s it for this video! To continue your learning, check out one of the videos on screen now, and I’ll catch you in the next lesson. Don’t forget to follow us on Facebook, Twitter, LinkedIn, and visit theengineeringmindset.com.
—
This version removes any informal language and maintains a professional tone while preserving the original content’s meaning.
Pump – A device used to move fluids, such as liquids or gases, by mechanical action. – The engineering team installed a new pump to increase the efficiency of the cooling system in the power plant.
Head – The height of a fluid column, or the energy per unit weight of fluid, used to express the potential energy of a fluid system. – Calculating the head loss in the pipeline is crucial for designing an efficient water distribution network.
Pressure – The force exerted per unit area within fluids, crucial for understanding fluid dynamics and system behavior. – The pressure in the reactor vessel must be carefully monitored to ensure safe operation of the nuclear plant.
Flow – The movement of fluid from one location to another, often described in terms of velocity or volume per unit time. – Engineers must calculate the flow rate of the coolant to prevent overheating in the engine.
Liquids – Substances that have a definite volume but no fixed shape, adapting to the shape of their container. – Understanding the properties of liquids is essential for designing hydraulic systems.
Friction – The resistance that one surface or object encounters when moving over another, affecting energy loss in systems. – Reducing friction in the pipeline can significantly improve the efficiency of fluid transport.
Energy – The capacity to do work, which can exist in various forms such as kinetic, potential, thermal, and more. – The conversion of solar energy into electrical energy is a key focus of renewable energy engineering.
Charts – Graphical representations of data used to analyze and interpret engineering and scientific information. – Engineers use charts to visualize the relationship between temperature and pressure in thermodynamic processes.
Operation – The functioning or performance of a machine, process, or system, often requiring careful control and monitoring. – The operation of the new automated assembly line has increased production efficiency by 30%.
Measurement – The process of obtaining the magnitude of a quantity relative to a defined standard, essential in engineering and physics. – Accurate measurement of material properties is crucial for ensuring the structural integrity of the bridge.
