Self priming pump: Types, 
advantages and disadvantages
Know all about self-priming pumps in this guide.

Table of Contents

What is self-priming?
Types of self priming pump

Self priming centrifugal pump
Self priming water pump
Seal-less self priming pump
Self priming chemical pump
Vortex self priming pump
Liquid ring self priming pump
How do self-priming pumps work?
Key points for operating self priming pump 

Avoid dry start
Avoid backpressure
Use a strainer
Use end seals
Suction line
Uses of self priming pumps

Construction
Agriculture
Industry
Advantages 
Disadvantages 
FAQs

Why are self-priming pumps not used in the houses?
What happens if the pump isn’t primed?
Which kind of pump doesn’t ever need priming?
What is a Compressed Air Self-Priming Pump?




What is self-priming?
A self-priming pump has an external surface casing that centrifuges the
volute or pumps inside. Liquids have been added to the case, and the pump is
now ready to operate. Self-priming pumps are similar to centrifugal pumps
with extra features.

Fluid circulates inside the pump head of self-priming pumps, creating a
vacuum. Air in the suction pipework is expelled, and the pump’s impeller
is filled with liquid. Since there is a separate chamber inside the pump
head, self-priming pumps are less efficient. 

Additionally, self-priming pumps handle a wide range of fluids and work well
with solids, corrosive liquids, and slurries.



Types of self priming pump
Basic knowledge of pump technologies is necessary when choosing a self-priming
pump.


Self priming centrifugal pump
A priming pump can pump gas, a liquid, or a mixture of both. If there is
water inside the pump’s body, it can use suction to generate a vacuum.


Self priming water pump
For both industrial and commercial uses, this pump primarily pumps clean
water. Centrifugal pumps with a 40 liters per minute maximum flow rate are
used for these pumps.


Seal-less self priming pump
This pump moved a variety of fluids, slurries, solvents, salts, and acids.
This pump is used for heavy work.

This pump works by being split into two parts: a stiff thermoplastic
interior and a blendable outside wall.


Self priming chemical pump
This self-priming pump enables the flow of oil, pigments, sewage, and water.
The pump is quite similar to the self-priming centrifugal pump.


Vortex self priming pump
Pure low-viscosity liquids devoid of any particles are pumped with this
pump. A simple design and simple operation make up for the relatively modest
capacity.


Liquid ring self priming pump
Foaming liquids are controlled with this pump. Water, black oil, and diesel
fuel are also suitable for them. However, these pumps inexorably leak some
of the working fluid transported outside the pump and the pushed media.

see also all about reciprocating pumps



How do self-priming pumps work?
At the impeller, air enters the pump and combines with water. The
impeller’s centrifugal force causes water and air to be discharged into
the reservoir simultaneously. As a result, water naturally tends to sink,
but the air naturally rises.

Water without air, which is now heavier than water with air, flows downward
by gravity into the impeller chamber, where it is ready to mix with
additional air entering the suction line. The suction line becomes vacuumed
when all air has been removed, and pumping starts due to atmospheric
pressure forcing water up the suction line and toward the impeller.

When the pump starts to pump, the water no longer circulates inside. The
pump will self-prime the following time it is turned on, which means it will
be able to combine the water and air in the casing once more to produce a
pumpable fluid until the pump is fully primed.

On the other hand, a standard centrifugal pump includes a built-in water
reservoir that allows it to prime by recirculating water inside the pump,
clearing the air from the pump and suction line. The location of this water
reservoir can be either above or in front of the impeller.
 


Key points for operating self priming pump
 

Avoid dry start
Priming is done before pumping begins to prevent a dry start, possibly
leading to a pump breakdown.
 

Avoid backpressure
Pay close attention to installing a bypass filling line to prevent back
pressure in the discharge line, which could obstruct the priming procedure.

Airflow via the suction line is blocked by the backpressure that builds up
in the discharge line due to air bubble accumulation.
 

Use a strainer
It is necessary to install a filter when using a pump in a dusty location to
avoid solids building up in the filling compartment.
 

Use end seals
End seals are recommended for self-priming pumps. If the stuffing box seal
fails, air may be trapped, making the filling more difficult and lowering
the functional quality.
 

Suction line
Since the suction line is constantly below atmospheric pressure, air leakage
is possible. Therefore, when the pump runs, the suction line should be at
0.5 meters (20 inches) of vacuum.
 
Uses of self priming pumps
 

Construction
Self-priming pumps can be used for numerous purposes in construction. These
include groundwater drying and lowering, water supply from wells or
channels, washing concrete surfaces, pumping out floodwaters, wastewater
conveyance, firefighting, hazardous liquid collection, and water evacuation
from pits or basins during excavation. In addition to being utilized to
produce building materials, self-priming pumps are also used to maintain and
repair utility networks and systems.
 

Agriculture
Self-priming pumps are used for agricultural needs such as surface
irrigation and watering, pumping and spraying liquid fertilizers or manure,
distributing liquid animal feed, and handling oil cake, brand-new wines, and
fruit juice.


Industry
Self-priming industrial pumps are utilized at various manufacturing
facilities, in oil storage tanks, to clean up spills at chemical plants, and
in the mining, metallurgical, pulp and paper, water supply, and drainage
industries.
 


Advantages

Self-priming pumps, transmission hardware, and power machines are relatively
less expensive than other pumping machines.
It is simple to maintain because the main component is above the water surface. 
There is no need to transfer the power machine when dismantling since the
lifting height is short, and the pump room is small.
Certain self-priming pumps are capable of handling particles up to 3 inches.
It is possible to pump fluid with a self-priming pump even when it is not
submerged. This offers more flexibility than a submersible pump, which must be
submerged to maintain prime and perform as intended.

 


Disadvantages

Although the term “self-priming” indicates that the pump does not require 
priming, manual priming may once in a while be required.
It frequently needs higher clearances to handle solids more effectively for
its inefficiency. It also requires a larger volume to help with self-priming.
The liquid supply is farther distant from the pump. Therefore, a minimum pipe
length is required to assist minimize air leakage and suction pressure loss.
The motor needs protection when the water level in the input tank is high.
The self-priming pump’s practical suction range is exceeded if the water level
in the inlet tank is too low, making it unable to suction water.

 


FAQs

Why are self-priming pumps not used in the houses?
The suction line has an air leak, which causes air to be forced out of the
discharge when the pump circulates fluid to establish a low-pressure zone.


What happens if the pump isn’t primed?
Without priming your pump, you risk mechanical seal failure and subsequent
harm to other crucial pump parts.


Which kind of pump doesn’t ever need priming?
Plunger pumps are self-priming when used above or below the fluid level.
Therefore, they don't need to repeat the priming process each time.


What is a Compressed Air Self-Priming Pump?
A compressed air self-priming pump is pushed through a jet into a tapered
tube to produce a vacuum. It is pulled in and released with air from the
pump casing and suction line.