Table of Contents
When selecting a slurry pump, the pump’s head is an essential consideration. So how do we calculate the head of a slurry pump? How is head classified? How can we achieve optimal pump efficiency? Pansto will provide answers to each of these questions.
What Is Pump Head
Simply put, pump head is the height of the liquid that the pump draws out of the pool, pressurizes it, and then lifts it to a certain position.
The unit of measurement for pump head is meters or feet, and it is an important parameter to measure the delivery capacity of the pump. Combined with the pump curve, it can determine the flow rate that the pump can pump when the pump head is at a specific height.
If you want to understand the pump head clearly, you must first understand the components of the pump head. The pump head consists of suction head, discharge head and total head.
Suction Head
The suction head refers to the vertical height distance between the liquid level in the water pool and the pump suction inlet.When calculating, we need to pay attention that the suction head also needs to consider cavitation and pipe friction.
Suction conditions are also relevant to the pump head.If the suction level is lower,the head measured will be less,and vice versa.The pump’s motor converts electrical energy into mechanical energy,which the pump then imparts into the fluid as pressure.
Raising or lowering the suction level therefore adjusts the potential pressure of the liquid.The more pressure the pump delivers,the higher the head will be.
Discharge Head
The discharge head refers to the vertical distance from the pump outlet to the maximum height the pump can lift the liquid.
Like the suction head, this does not refer to the simple vertical height. In practical applications, we also need to consider the horizontal distance of the pipeline and the friction loss of the pipeline.
Total Head
The total head refers to the sum of the suction head and the discharge head. But it does not mean that this is the total head. There is another important parameter, namely the pipeline loss, which will be explained in detail in the following content.
Read the following so you can understand total head formula calculations more clearly.
Because pump manufacturers cannot know the suction level parameters, they calculate the pump’s total head. To do this, they subtract the total suction head, which is measured as height above sea-level, from the total discharge head.
The next important consideration is how much friction needs to be taken into account. Friction loss depends on the length and size of the pipework, bends, and gate valves, through which the fluid flows. The sum of the head and friction loss will give total head.
Total head is a more reliable indicator of pump performance than pressure because it indicates what the pump can do regardless of the suction conditions. The total head combined with your flow requirement will allow you to choose the right pump.
How To Calculate Pump Head?
Total Pump Head Formula
H=Hd + Hs
H=Total Head
Hs=Suction Head
Hd=Discharge Head
(The total head formula only applies to simple cases.)
When the liquid level is above the pump inlet, the pump is in positive pressure suction, so the suction head is positive. Conversely, the pump is in negative pressure suction, and the suction head is negative. (refer to the figure below)
Notes On Pump Head Calculation: Static Pressure
When we calculate the total head of the pump, we need to pay attention to one issue, the vertical distance between the liquid level and the pump inlet.
When the liquid level is above the pump inlet, the liquid provides static pressure to the pump. Therefore, we can understand that the greater the vertical distance of the liquid level above the pump inlet, the greater the static pressure it provides, and the higher the pump can lift the liquid (note: Also consider pipeline losses).
Factors Affecting Pump Head
1. Pipeline loss: When fluid passes through a pipe or elbow, it will produce losses such as friction, impact, and vortex.
2. Fluid density and viscosity: When the fluid we transport is not just clean water, for example, when using a slurry pump to transport slurry, silt, etc., the pump needs a higher head to overcome these difficulties.
3. Flow rate: Generally speaking, the flow rate of a pump is inversely proportional to the head, that is, when the flow rate increases, the pump head will decrease, and conversely, when the flow rate decreases, the head will increase.
Of course, sometimes the relationship is not inversely proportional. Read the following content to learn more about the pump performance curve.
How to Read and Use Pump Performance Curves for Proper Selection?
How To Read A Pump Curve?
Before reading a pump performance curve, you must first understand the definitions of the values in the curve.
For example, the pump performance curve of the PHH-Series Heavy Duty Slurry Pump shown in the figure.
Flow rate: The X-axis is the flow rate of the pump, in m3 /h, which represents how much flow the pump can deliver.
Head: The Y-axis is the pump head, measured in meters, which represents how high the pump can lift the fluid.
Efficiency: Efficiency is expressed in %. The larger the value, the higher the efficiency of the pump and the better the performance of the pump.
How To Select A Pump From Curve?
1. Determine your job requirements
For example, you need a pump head of 50m and a flow rate of 600m3 /h.
2. Find the right pump operating point
Intersection point: Find the intersection point of the X-axis (600m3/h) and the Y-axis (50m) in the graph and see which curve it is on.
Rotational speed: For example, if point A is near the 1140r/min curve, it means that this model may be selected.
3. Check efficiency and NPSH
Efficiency: Point A falls near the 52% efficiency curve, indicating that the efficiency of the pump is 52%.
NPSH: NPSHr (net positive suction head required) is about 8m at point A, so the NPSHa (net positive suction head available) of the pump must be greater than 8m to ensure the minimum pump inlet pressure, otherwise cavitation may occur.
Note: This step is a simple selection. In actual application, the density, viscosity and on-site working conditions of the fluid must also be considered. If necessary, please be sure to contact the pump manufacturer for selection.
Understanding Pump Head Pressure
In any pumping system, understanding head pressure is essential for optimal performance and efficiency. Pump head pressure refers to the height to which a pump can raise water, reflecting the energy transferred to the fluid to overcome resistance in the system. This is a fundamental aspect that impacts flow rates, power consumption, and overall system design.
At Pansto Pumps, we are committed to providing high-quality, reliable pump solutions tailored to meet the unique needs of our clients. Whether you’re managing mining operations or industrial applications, understanding pump head pressure helps ensure you select the right pump for maximum efficiency and safety.
Key Points to Remember:
- Head pressure is vital for determining pump capacity. It helps in assessing the required power and energy efficiency of a system.
- Proper selection and understanding of head pressure prevent costly operational issues.
- Trust Pansto Pumps to guide you through selecting the best pumping solutions for your needs, contact our expert for your solutions..
Avoid Confusion: Head vs Pressure
Head and pressure are two completely different concepts, but they are closely related to each other.
Head can sometimes be confused with pressure,purely because there is a close relationship between the two parameters but there is one fundamental difference.
Head is fluid independent,that is,regardless of the fluid’s relative density,the pump will lift it to the same height.Therefore,it does not matter whether the fluid is water or heavy sludge.
Pump head is how high the pump can lift the fluid, which has nothing to do with the density of the fluid. Pressure is the pressure the fluid is subjected to in the pump and pipeline, which is related to the density of the fluid.
Pressure,on the other hand,is fluid dependent and is affected by gravity.Therefore,the same head will generate a different pressure depending on the fluid’s relative density.
For example, there is a pump with a pump head of 50m. If we use this pump to transport clean water and slurry, the pressure of the fluid will be greater because the density of the slurry is large, but the head of the two fluids will not be affected and will both be 50m.
Different Between Rated Head and Maximum Head
The rated head is the head of the pump when it is at its optimal efficiency point. At this time, the pump has the best efficiency, the most stable operation and the longest service life.
The maximum head is the head at 0 flow, also known as the shut-off head. This is only a head limit value. In actual work, the pump head must not exceed 110%-120% of the rated head, otherwise the pump will be unstable during operation and shorten the service life of the pump.
What Is Head Range In Water Pump?
The head range is the range between the minimum and maximum head that the pump can provide when working.
Simply put, it is the vertical difference between the minimum and maximum heights that the pump can lift water. It can also be understood as the range of energy that the pump can provide after overcoming friction and the gravity of water.
The head range is generally expressed in m. For example, the head range is 5-35m. The head range can help you choose a suitable model when selecting a pump, and it is an important parameter for pump selection.
FAQ
Which Pump is Suitable for Small Discharge and High Head?
1. Piston pump/plunger pump: Piston pump is a positive displacement pump. It relies on the movement of the piston in the pump to squeeze the water and discharge it. The pressure is very high and the discharge is very small. It is suitable for precision and high-pressure working conditions.
2. Multistage centrifugal pump: Multistage centrifugal pump has multiple impellers, each of which can provide a part of the head. The head is very high and suitable for medium and low discharge and high head high pressure working conditions.
3. Diaphragm pump: Diaphragm pump is also a positive displacement pump. It relies on the reciprocating motion of the diaphragm in the pump to move water. It has a higher pressure and is suitable for medium and low flow conditions.
What is Static Head of Pump?
Static head refers to the vertical height difference from the water source suction port to the discharge port of the water pump without considering factors such as pipe friction.
The static head is generally used to preliminarily determine the head required by the pump.
What is Pump Shut Off Head?
As the name suggests, the shut-off head is the head of the pump when the pump outlet is closed. At this time, the pump flow is 0 and the pump pressure is maximum. It can also be understood as the maximum head or dead head of the pump. However, the shut-off head is only a theoretical data used to determine the ultimate pressure that the pump can withstand.
Pump Capacity Vs Head
The pump capacity and pump head are inversely proportional on the pump curve. When the pump capacity (flow rate) is larger, the head will be smaller. Conversely, when the pump capacity (flow rate) is smaller, the head will be larger.
The unit of pump capacity is generally expressed in m³/h, and the head is expressed in m.