Sliding Vane, centrifugal, and gear pumps are three of the most commonly used pumps for fluid handling, all of which have different purposes and best areas of application. It can sometimes be difficult to choose the one that meets your exact requirement; however, understanding the difference between the three pumping technologies and their working principles will help you make an informed decision. In this article, we’ll cover everything you need to know about these pumps in detail:
Sliding Vane Pumps
A sliding vane pump is a positive displacement pump that consists of blades or vanes that slide in and out of slots in the pump rotor, eccentrically supported in the cam to form a crescent shaped cavity. This cavity traps a certain amount of fluid and forces it into the discharge pipe with each rotation. What goes in is exactly what comes out. No more, no less. These pumps provide a constant flow of fluid at a given speed, and can overcome pressure differences. They are also referred to as rotary vane or constant-volume pumps.
Centrifugal Pumps are one of the most commonly used pump types in the world. It consists of an impeller, which rotates and creates a centrifugal force that imparts Kinetic energy to the fluid, inducing a flow from a low level to a high level. These pumps are widely used within mining, manufacturing, and agricultural industries due to their large volume handling capacity, small size, user-friendliness, and easy maintenance features.
A positive displacement gear pump uses the meshing of two or more rotating gears to form a liquid seal with the casing, which creates a vacuum at the inlet and moves the fluid to the outlet. These pumps are mainly used because of their flow-rate & volume controlling capability. If the pressure within the system remains constant, these pumps can provide more or less fixed fluid flow rate.
Differences – Sliding Vane vs. Centrifugal vs. Gear Pumps
Sliding Vane Pumps
Flow rate remains constant regardless of pressure at inlet
Flow rate varies with pressure at inlet
Flow rate remains constant
Fluid Viscosity Range
Designed for low viscosity fluids (up to 500 CPs)
Recommended for fluids with lower viscosity (up to 500 – 600 CPs)
Ideal of high viscous fluids
To transfer Fuel, Aviation Fuel, LPG, Ammonia, refrigerant coolant, etc…
Used for general water supply, to pump sewage agriculture, fire & safety, heating & cooling application.
Mainly used to pump ink, paint, chocolate, honey, gels, tar, resin, bitumen, lube oil, chemicals, and highly viscous food syrups, etc…
Works better when pressure increases
Peaks at specific pressure, variations drastically reduce efficiency
Designed to perform as pressure rises
handles a wide range of fluid temperatures
Can handle up to 120°C
Can handle up to 400°C
Can they Run Dry?
Yes, but only for short period of time (provided the gear has self-lubrication)
Good (based upon fluids being handled)s
Not so expensive
Benefits and Drawbacks
Now that we understand the principles of operation & differences for each type of pump, let us go through the benefits and drawbacks associated with each technology:
Sliding Vane Pumps
Capability to manage thin/less viscous fluid effectively
Operates at a stable flow rate, thereby ideal to use for motoring
Limited capacity with high - pressure requirements
Fluid delivery is pulsating in nature
Not suitable for liquid with solid contents
Not suitable for highly viscous fluid.
Cannot close the discharge valve
Requires safety valve at discharge to prevent mechanical failure
Zero chance of leakage unless casing is broken.
Lower rate of pump deterioration.
It functions with minimum noise.
Magnetic coupling will break under heavy load thus saving the motor.
Gap between the motor & pump will restrict the entry of fluid.
Coupling might slip in case of a sudden heavy load
If the pumping liquid contains any iron particles, will be collected on the impeller due to magnetic drive, which may leads to clog the pump.
Can handle high density or viscosity
Easy to Use and Maintain
Produces Loud Noises
Displacement Cannot Be Adjusted
Not suitable for fluids with solid/abrasives.
When, Where & Which Pump to Use?
To choose between Sliding Vane, Centrifugal, and Gear Pumps is not always easy without a clear understanding of its features and differences. Below are some of the industries where these pumps are commonly used:
Sliding Vane Pump
Fire & Safety
Food & Beverage
Oil & Gas
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