Specific Gravity and Pump Selection
May 27, 2021
When choosing the right pump, one of those factors is the Specific Gravity (SG) of the fluid you intend to move. If it’s water, SG is not a worry. But, if you are working with other types of fluids, you must consider the effect the fluid type will have on your pump’s performance and efficiency, and on its ability to provide you with long, maintenance-free service.
Specific Gravity Defined
The density of a substance is defined as its mass per unit volume. Water has a density of 997 kg/m3 or 62.43 pounds per cubic foot. The term specific gravity refers to the density of a substance, such as another fluid, relative to the density of water.
Specific gravity is important when sizing a centrifugal pump because it’s the determining factor in terms of a fluid’s weight. Fluid weight has a direct impact on the amount of work that your pump can perform which will, in turn, determine factors such as the amount of horsepower needed and the pressure that the pump can develop.
How does Specific Gravity affect power consumption and pressure?
The presence of solids increases the Specific Gravity (SG) and weight of the fluid being moved. The higher the Specific Gravity, the more motor power is required. For example, wastewater with an SG of 1 will have little impact on motor power, while slurries or sludges with a higher specific density and weight will require more motor power. In fact, the increase or decrease in power consumed is directly proportional to the specific gravity of the liquid being moved.
The pump’s pressure will change in direct proportion to the specific gravity of the fluid to be moved. While a pump may develop about 50 PSI (Pounds per Square Inch) while pumping water, when pumping a fluid with a SG of 1.2, it will only develop pressure of 41.7 PSI. We get this figure by dividing 50 by 1.2. Specific gravity is a relevant consideration when you are selecting a pump to develop a given pressure.
What’s the best advice we can give, all of the above considered? Seek professional help when choosing a dewatering pump. That way, you can be certain that the equipment you are using aligns with the needs of your application. The professionals at Atlas Copco are experts in pumps and the myriad number of applications to which they can be assigned. Hopefully, you now have a better idea of what questions you should ask yourself. You can get the answers you need from an Atlas Copco pump equipment expert.
About Andreas Neufeld
Our Pumps Product Marketing Manager, Andreas, started his pumps career in technical service, working through applications with customers and now manages the pumps portfolio for the North American region.
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Understanding Specific Gravity in Centrifugal Pump Applications within the United Arab Emirates
In the United Arab Emirates (UAE), industries such as oil and gas, petrochemicals, and water treatment frequently handle fluids with varying specific gravities. For instance, Dubai Crude Oil has a specific gravity of approximately 0.871
Accurately assessing the specific gravity of these fluids is crucial for selecting and operating centrifugal pumps to ensure optimal performance and efficiency.
What is specific gravity?
Specific gravity is the ratio of a fluid's density compared to the density of water at a standard temperature. It indicates whether a fluid is heavier or lighter than water.
Why is specific gravity important in pump selection?
Specific gravity affects the fluid's weight, which influences the pump's power requirements and the pressure it can generate. Pumping fluids with higher specific gravities than water demands more energy and can alter the pump's performance
How does specific gravity impact centrifugal pump operations in the UAE?
In the UAE, where industries handle fluids like crude oil with specific gravities different from water, understanding specific gravity is essential. It ensures that centrifugal pumps are appropriately sized and operated to handle the unique properties of these fluids, maintaining efficiency and longevity.