Standard centrifugal pumps have no self-priming capability and are incapable
of pumping when water flow is discontinued in the suction pipe. The oval
shaped self-priming pump has weak self-priming force at locations where
back pressure is present, and the higher the pump head, the harder to self-prime
The YOKOTA Self-Priming Centrifugal Pump has the same pumping capability
for high head pumping as other centrifugal pumps, however its self-priming
force is extremely strong at 60-90kPa (6-9m water column), which enables
the pump to be used even under extreme conditions.
For suction pumping with outstanding self-priming power:
For intake piping across embankments or long intake pipes:
Priming strengthened UHNS/UHNK types
For high density slurry:
Slurry resistant UHT type
For installation in places subject to submersion:
UHPR type with submersible motor
For self-priming sanitary specifications:
Features of the YOKOTA Self-Priming Centrifugal Pump
Outstanding self-priming power
The internationally patented water-air separating mechanism reaches a maximum
vacuum of 60-90kPa (6-9m water column) and displays outstanding self-priming
No problem with suction of air during pumping
A large amount of incoming air can be separated and discharged during pumping.
Even if pumping becomes subject to suction or mixture of air due to fluctuations
of suction conditions, it continues pumping, constantly discharging air,
and restores normal pumping operation as soon as suction conditions return
to normal. Even continuous suction of air-containing water (i.e., gas-liquid
two-phase pumping) is possible.
Even if cavitation develops due to fluctuations of suction conditions such
as water level, temperature, or vacuum level on the suction side, this
pump can still continue its pumping operation. Therefore, this pump does
not require allowance for NPSH, and enables stable pumping operation even
under fluctuating suction conditions. It naturally shows outstanding performance
for extraction from sealed (vacuum) tanks.
Simple structure without any inlet valve, No need for a foot valve
Due to its simple structure without any inlet check valve, it is robust
and easy to maintain. Moreover, there is no need for installing a foot
valve or an intermediate valve on the intake side under ordinary operating
Operation is also easy with no need for priming.
Intake piping across embankments or long intake piping is possible
Because of superior intake power, intake pipes can be installed across
Intake piping with long piping is also possible.
Outstanding pumping performance
This single-suction, single-stage centrifugal pump displays outstanding
pumping performance in a wide range of specifications.
Large selection of models, Large selection of materials
Construction that can meet a wide range of specifications
Standard constructions include semi-open impellers for small pumps and
closed impellers for medium and larger pumps.
The impeller has been improved to form ideal blades for high efficiency.
An oil bath lubrication system is adopted for bearings.
Maintenance is easy to perform because construction is simple and the number
of parts in the water passage section is minimized.
All special material products are manufactured internally in a continuous
process to ensure stable quality.
Principle of self-priming (PAT.)
The pump casing consists of a smaller passage and a larger passage forming
a semi-double volute and a cavity holder in the discharge nozzle.
1. Flow of circulation
During self-priming, the water discharged from passage A in the semi-double
volute returns to the impeller through passage B-C, and is discharged again
into passage A.
2. Removal of bubbles
This recirculation flow mixes the water and the air in the center with
intense vortex D within the impeller and discharges it into passage A.
3. Water-air separation and exhaust
The water-air mixture is led from passage A to discharge nozzle B in a
cyclonic state and automatically separated by centrifugal force, and then
the water is recirculated through passage B-C. The separated air is then
held by cavity holder E, and compressed and discharged.
Self-Priming Centrifugal Pump UHN series
We are holding an "Online Exhibition" where you can experience
the same kind of tour as a real exhibition on the web.
In addition to the Self-Priming Centrifugal Pump, we are exhibiting many
videos that are based on actual examples, including operation examples
of various pumps and valves such as defoaming/degassing pumps, and evaluation
methods of operation results.
(> "Online Exhibition" page)
The YOKOTA Self-Priming Centrifugal Pumps can be used even under extreme
conditions. They can be used, for example, as chemical pumps for liquids
containing air, pumps for mixing air bubbles in an aeration system (i.e.,
gas-liquid two-phase flow pumps), condensate pumps, drain pumps, and pumps
for extraction from sealed tanks.
Acids, Alkaline liquids, Solvents, Slurry liquids, other
Brewery, Sugar refining, other
Seawater, Slurry liquids, other
Pulp, Effluent, White water, Black water, other
Exhaust gas desulfurizer (Limestone slurry pumps, other), Seawater, Water
Ultra-pure water manufacturing devices, Acidic waste water, Polishing waste
water treatment, other
Aquarium, Fish farming:
Seawater suction, Circulation pumps, other
Hot springs, Hot oil, other
Example applications and installations (Special cases where difficult pumping conditions are present)
For aquariums ... UHN type
Made of extraordinary seawater resistant YST alloy
Various types of mechanical seals can be installed.
Mechanical seal (oil bath)
Oil-bath lubrication allows dry operation.
We can also provide double mechanical seals.
Special material products are manufactured internally in a thoroughly continuous
process from casting under complete material and heat-treatment control.
YOKOTA's corrosion and wear resistant special stainless steel casting (YST)
has been adopted for anti-pollution devices, seawater pumps, and other
pumps, acquiring highly reputable results.
For details, please refer to Special Stainless Steel YST series.
Priming strengthened types for intake piping across embankments
or long intake pipes
Water-air separating impeller is installed in the main pump of UHN type
to enhance self-priming with vacuum pump.
Main pump is standard UHN type.
Self-priming strengthened by vacuum pump in order to reduce self-priming
time in long suction piping.
Automatic operation with No-Feed Detector and priming-water detector.
High corrosion and wear resistance type for high density slurry
The front and rear plates (wear resistant plates) are installed to protect
Economical selections can be made from a wide variety of models similar
to the UHN type.
Impeller configuration can be selected depending on use.
A wide variety of materials, such as YOKOTA's corrosion and wear resistant
special stainless steel casting (YST), are available.
Wear resistant plates are installed for handling high density slurry.
Gland packing, mechanical seals and Non-External-Flushing Mechanical Seals
can be selected depending on use.
Combined with submersible motor for installation in places subject to submersion
For installing pumps in such places as floodplains or basements, where
there is a possibility of submersion, it is safer to use the UHPR type
composed of a UHN type pump and submersible motor which is trouble-free
in such situations.
For details on related dimensional outline drawings, please contact us.
High washability self-priming sanitary pump
This is a self-priming pump whose disassembling and cleaning work is easy,
most suitable as CIP cleaning water pump and air entrained liquid feed
pump in the food and chemicals sectors which require sanitary properties.
For details on related dimensional outline drawings, please contact us.