Self Priming Pump vs Non Self Priming Pump: 5 Key Differences in Priming Mechanism
Pumps are essential tools in modern life, moving water, fuel, chemicals, and wastewater across homes, farms, factories, and industrial sites. Among the wide range of pump types, self-priming pumps stand out for their unique ability to start operating without manual liquid filling. In contrast, non self-priming pumps require pre-filled liquid before startup. Understanding their core differences, especially in activation and priming mechanisms, helps you select the right equipment for the job—Virheos offers in-depth product specs, performance comparisons, and expert guidance to refine your choice further.
What Is a Self Priming Pump?
The characteristic of a Self Priming centrifugal pump is the ability to automatically extract air from the suction tube and casing automatically. Once activated, it will generate a vacuum and draw the liquid into the pump using atmospheric pressure. This' self Priming 'function does not require manual filling of liquid before each use.
Unlike non self priming pumps, which stop working if air enters the system, self priming pumps keep trying until liquid flows. This enables them to operate reliably in situations such as liquid level drops, pipeline blockages, or air leaks. For example, they can work properly in flooded basements, uneven water levels in farmland, or boats that need to fetch water from different depths.
Key Components of a Self Priming Pump and Their Functions
To understand the working principle of self Priming pumps, let's take a look at their core components. Each component plays an important role in the work and maintenance startup process.
1. Casing
The casing of the self Priming pump has a special design. It contains a start-up chamber - a small space that extracts liquid when the pump stops. These are used as "seeds" by the liquid to restart the pump. When the pump runs again, the starting chamber will release liquid mixed with the intake air to help clean the system.
2. Impeller
The impeller is a rotating disk with curved blades. It rapidly rotates to push the liquid outward, thereby generating pressure. In an automatic start pump, the impeller can generate sufficient suction to lift the liquid from a low water level (such as a 20 foot deep well) and can also handle light solid liquids (such as mud and water).
3. Suction Port and Discharge Port
The suction port draws liquid (or air) into the pump. The Discharge Port pushes the liquid out to the target area. In self priming pumps, the suction port is usually larger or better shaped to reduce air blockage. To ensure that the pump can effectively extract liquid even through long or narrow pipelines.
4. Shaft and Motor
The shaft connects the motor and impeller to transmit rotational kinetic energy. The motor drives the shaft to rotate the impeller. High quality automatic start pump motors can withstand brief dry runs (when there is air) without overheating.
5. Seal and Bearings
Sealing can prevent liquid leakage from the casing. Bearings support the pump shaft to reduce friction. In self Priming pumps, seals are typically made of durable materials such as ceramics or carbon to withstand repeated starting cycles. Bearings must be lubricated to last longer even under different loads.
Types of Self Priming Pumps
Due to differences in design and usage, self priming pumps are divided into the following types.
1. Self Priming Chemical Pump
This type is made to handle corrosive or hazardous liquids such as acids, solvents, and industrial chemicals. The wetted parts use resistant materials like stainless steel, polypropylene, or PTFE. A self priming chemical pump can remove air from the line and start moving dangerous fluids safely. It is common in chemical plants, laboratories, and waste treatment facilities where leaks must be avoided and reliability is vital.
2. Self Priming Sewage Pump
A self priming sewage pump is built for wastewater that contains solids, fibers, and organic matter. It can pass items like rags, small plastic pieces, and fecal matter without clogging. The volute and impeller have wide passages, and the priming system clears air even if the suction line contains debris. You will find this pump in municipal sewage stations, septic systems, and commercial buildings where wastewater must be moved quickly.
3. Self Priming Submersible Pump
This kind works while fully underwater. It combines submersion capability with self priming action, so it can start in a dry or partially filled sump and still draw liquid effectively. The motor is sealed against water ingress, and the casing holds a priming reserve. Self priming submersible pumps serve in deep wells, flood control, basements, and marine bilge systems. They are chosen when the pump must stay in the liquid or operate in hard‑to‑reach places.
4. Self Priming Irrigation Pump
Farmers and landscapers use a self priming irrigation pump to move water from rivers, ponds, or storage tanks to fields and gardens. It handles uneven terrain because it can lift water from lower levels and clear air from long suction pipes. The robust construction resists wear from sand or silt in the water. Typical uses include crop irrigation, greenhouse watering, and large‑scale turf maintenance.
5. Self Priming Trash Pump
A self priming trash pump is a heavy‑duty version for liquids laden with solid debris. The impeller and volute are oversized, and the intake is reinforced to resist impact from stones, sticks, and metal fragments. It is widely applied on construction sites, mining operations, and disaster cleanup tasks where mud, slurry, or mixed waste must be shifted fast.
6. Self Priming Centrifugal Pump
This is the most common form of self priming pump. It uses a rotating impeller to create centrifugal force, pushing water outward and generating flow. The self priming centrifugal pump works well with clean or slightly dirty water, such as in household supply, light industrial service, and general dewatering. Its simple design makes it easy to maintain, and it offers steady performance in many routine applications.
Each type of self priming pump solves a particular problem. For example, a self priming chemical pump protects against corrosion, while a self priming sewage pump avoids clogs. A self priming submersible pump reaches difficult spots, and a self priming irrigation pump adapts to farmland needs. Meanwhile, a self priming trash pump tackles rugged debris, and a self priming centrifugal pump covers everyday water transfer. Choosing the correct variant ensures efficiency, durability, and fewer interruptions in your workflow.
How Do Self Priming Pumps Work?
The working process of a self priming pump can be split into three stages:
Stage 1: Initial Startup (With Air in the Line)
When we start the self priming pump, the motor drives the impeller to rotate, pushing air outward. The pressure inside the pump casing will decrease as a result, creating a partial vacuum. Then, external atmospheric pressure pushes the liquid from the source (such as a storage tank or well) into the suction pipeline.
Stage 2: Liquid-Air Mixing and Separation
When the liquid enters, it will mix with the air in the startup chamber. The impeller continues to rotate, decomposing the mixture into tiny droplets. Heavier droplets fall into the bottom of the startup chamber, while lighter air rises. Then, the pump discharges air through the exhaust port, leaving liquid in the starting chamber.
Stage 3: Continuous Operation
Once the chamber is filled with liquid, the pump works like a standard centrifugal pump. The impeller pushes the liquid out while new liquid is drawn in to replace it. If air re enters (e.g. from a leak), the pump will automatically repeat the start-up process.
Applications of Self Priming Pumps
Self priming pumps have a wide range of applications. They can be useful in many situations:
Agriculture: irrigate uneven terrain fields, drain flooded crops, or supply water to livestock storage tanks.
Residential area: Pump water from the basement, empty the swimming pool, or pump water from the rainwater tank.
Construction: Dehydration treatment, transportation of concrete slurry or cleaning equipment for construction sites.
Marine: Pump water from ship engines, extract bottom water (extract moisture from the hull), or clean decks.
Wastewater management: treating sewage, septic tank drainage, or industrial wastewater containing solids.
5 Key Differences in Priming Mechanism: Self Priming Pump vs Non Self Priming Pump
Now we compare these two pump types through the activation mechanism. These differences determine where and how they perform best.
1. Automatic vs Manual Priming
Self Priming Pump: Primes automatically. At startup, it will remove air and extract liquid without user intervention. Even after air enters (such as pipeline leakage), it will automatically restart. This can save a lot of time and labor, especially in remote or hard to reach areas.
Non Self Priming Pump: Requires manual priming. Users must fill the pump casing and suction line with liquid before starting. If air enters during operation, the pump will lose start and stop. Then the user needs to refill the system - a frustrating process for tasks like repeatedly draining flooded basements.
2. Casing Design: Trapped Liquid vs Simple Housing
Automatic Priming pump: The casing contains a starting chamber for liquid suction. This stored liquid will activate the self priming pump. Without it, the pump would have difficulty extracting liquid from the dry pipeline.
Non automatic Priming pump: The casing is simple and there is no liquid storage. And if air enters, there is no spare liquid to restart the process, so the pump will fail.
3. Impeller Function: Suction Focus vs Pressure Focus
Self Priming pump: The impeller has strong suction and can lift liquid from low water levels (up to 25 feet depending on the model). Some can even handle thick liquids (such as sludge) or small solids.
Non automatic Priming pump: The impeller focuses on pushing the liquid, not lifting it. When the pump is placed below the liquid source (such as a water tank on a roof), the impeller works best. If the liquid level is lower than the pump, they cannot lift the liquid.
4. Tolerance to Dry Starts
Self Priming Pump: Can handle brief dry runs. When air is present, the impeller spins without causing major damage. Built-in thermal protection prevents overheating. This is critical in emergencies (e.g., a sudden pipe burst) where the pump starts without liquid.
Non Self Priming Pump: Hates dry starts. Spinning in air creates friction, heating up seals and bearings. Over time, this leads to cracks, leaks, or motor failure. Users must ensure the pump is primed before every start—no exceptions.
5. Application Scenarios: Variable vs Stable Systems
Self Priming pump: suitable for systems with changing conditions. For example:
Wells with fluctuating water levels (rising and falling liquid levels).
The solid in the sewage pit blocked the pipeline, causing air to enter.
Mobile facilities (ships, trucks).
Non self Priming pump: most suitable for stable and leak free systems. For example:
Fixed water supply pipe (pump below water storage tank)
Industrial processes using closed and airtight pipelines.
In the laboratory, liquids always exist and air enters very little.
Conclusion: Choosing the Right Pump for Your Needs
The priming mechanism is the main advantage of self-priming pumps, which plays an important role in dynamic and unpredictable environments. They save workload, reduce downtime, and can handle unexpected situations such as air leaks or low liquid levels. However, for stable and controllable systems, non‑self‑priming pumps are simpler and cheaper. Find more info now to explore design differences, performance data, and real‑world use cases to select the right pump for your operation.
Reference
Self-priming pumps: An overview——This paper overviews self-priming pump technologies, explaining their ability to evacuate air from casings and suction lines without manual assistance. It contrasts the inherent limitations of traditional non-self-priming rotodynamic pumps, covering various design innovations to support end-users' selection for different industrial applications.——Read more
The Experimental Research on the Self-priming Centrifugal Pump of Jet Flow——This study introduces a jet-flow self-priming centrifugal pump with a self-circulation system. Experimental results prove it achieves 3~5% higher efficiency than traditional self-priming pumps, with shortened self-priming time and reduced weight, outperforming relevant national standards.——Read more