For harshest
pumping
conditions
FAQ. Knowledge base
FAQ. Pump head and total head for pump performance. What does the head of the pump mean?
Put simply, head is the height at which a pump can raise fluid up and is measured in meters or feet. We use it when specifying centrifugal pumps because their pumping characteristics tend to be independent of the fluid’s specific gravity, often referred to as relative density.
Avoid confusion: head vs pressure
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.
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.
Suction Levels
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.
Total head
Figure 1: Friction losses are affected by length and size of pipework, bends, gate valves, strainer and velocity of flow.
What Is Head of a Pump?
The pump head or discharge head of water pumps is measured by the power of a pump. The larger the pump head, the more pressure the pump can generate. This figure is measured in meters (or feet) and is calculated by placing a tube at the pump’s discharge and measuring the maximum height to which it can pump water.
Simply puts, the head of pumps is the maximum height that the pump can achieve pumping against gravity. Intuitively, if a pump can generate more pressure, it can pump more water & produce a higher head. The purest examples of this are if you have verticals pipes running straight up from the discharge outlet.
A pump with a 5 m head will pump liquids 5 m above the pipe 5 m from the discharge outlet. Also, note that the more liquid in the tank, the better the pump will be able to pump water into the vertical discharge pipe due to the suction head exerted by the liquid in the tank.
Pressure Vs Head:
Sometimes the head can be confusing with pressures when choosing a pump. There is a strict relationship between them which is defined by the fluid specific gravity, so the relationship is fluid dependents.
So what are the differences between pressure & head? As mentioned above, the head is the height given to the fluid by the pump and is measured in meters of the liquid column [m.l.c.] or simply indicated in meters [m].
A given head is fluid independent, meaning that different fluids with different specific gravities are all raised to the same height. Instead, the pressure is dependent on the fluid and is affected by the fluid density. The force of a fixed height liquid columns on a unitary sphere will change with different specific gravities. So, in these cases, the same head generates different pressure.
The pump head is not calculated directly. Manometers on the pump suction & delivery line give a measurement of pressure. The measurements given by the manometer show the differential pressure exerted by the pump between suction & discharges.
Total Head:
Another more useful measures of the head are the difference between the liquid level in the suction tanks & the head in the vertical discharge pipe. These numbers are known as the “total head” the pump can produce.
Increasing the level of liquid in the suction tank will lead to an enlarged head, and a decrease in the level will lead to a lower head. Pump manufacturers & suppliers often won’t tell you how much head a pump can produce because they can’t predict the height of the liquid in your suction tank.
Instead, they will report the totals head of the pump, the height between the level of liquid in the suctions tanks, & the height of a column of water that can be received by the pump. The total head is independent of the levels of liquid in the suctions tanks.
Mathematically speaking, the total vertex formula is as follows.
Total Head = Pump Head – Suction Head.
Pump Head Vs Flow Rate:
At maximum pump top, the flow to the water pump systems is zero. This is because the pumps cannot generate any pressures to move the water, as all the powers are being used to lifts the waters that are already in the system. When the pump head is zeros, the water flows at the maximums rates.
The result of a zero pump head is that instead of lifting, the pump’s energy can be applied entirely to the moving water; the flow is faster. As the pump head increases, the flow decreases, and vice versa. This relationship creates a unique graph of the operation area of an individual pump that can be used to select the right water pump for any job.
Of course, friction must be taken into account when the flow is introduced into the pump system. The force of friction between the water and the sides of the pipe further reduces the flow rate. When considering a flowing water pump system, total head = (Pump Head – Suction Head) + Friction.
We’re not going to discuss pipe friction in any detail here, but it’s important to know that if you’re going to pump long distances as well, you’re going to be affecting the overall pump head. The roughness of the pipe surface & the sharp bends in the pipework will have a significant impact on the pump head.
Pump Head Vs. Suction Head:
The suction head of a pump is similar to its pump head, except that it is the opposite. Rather than being a measure of maximum discharge, it is a measure of the maximum depth to which pumps can lift waters by means of suctions.
These are two equal but opposites forces that affect the flow of waters in pumps. As mentions above, Total Head = Pump Head – Suctions Head.
If the water’s level is higher than the pumps, the suction head is negative, and the pump head will rise. This is because the waters entering the pumps exert additional pressure on the suction.
Conversely, if the pumps are located above the waters to be pumped, the suction head is positive, and the pump’s head will decrease. This is because the pumps must use energy to bring the waters up to the level of the pump.
What Is a High Head Sump Pump?
High Head Sump Pumps are submersibles pressure pumps specially designed for applications with long pipe runs or heavy-duty high lift situations, dirty water, wastewater treatment systems, gray water, wastewater, water transfer, and industrial pressure For pump applications.
Water Pumps Now a comprehensive range of High Head Sump Pumps will ensure that you have a pump to suit your application. on any product listed for abundant information and specifications to aid in your High Head Sump Pump selection.
High Head Sump Pumps are submersibles pressure pumps specially designed for applications with long pipe runs or heavy-duty high lift situations, dirty water, wastewater treatment systems, gray water, wastewater, water transfer, and industrial pressure For pump applications.
Water Pumps Now a comprehensive range of High Head Sump Pumps will ensure that you have a pump to suit your application.
How Does a Sump Pump Work?
When a sump pit is filled with water, it reaches a set’s level on the pump, activating a switch & automatically turning on the sump pump. Most sumps pumps use centrifugal pumps with an impeller to move the water within the pits.
As the impellers push the waters out of the pit, more water flows out to fill the void, forcing the water to flow out through the pipe into the sump pit. A check valve in this pipe prevents water from flowing back, so it flows into the outflow pipe and away from the building.