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Self-Priming Centrifugal Pump

Self-Priming Centrifugal Pump
UHN series
(PAT.)

Outstanding self-priming performance even under extreme conditions

Self-Priming Centrifugal Pump

Patented in Japan, U.S.A., other

Bore

40-250mm

Total head

10-90m

Capacity

0.1-13m3/min

>Selection & Dimensions

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 water.
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:

UHN type

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:

SUH type



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 power.

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.

Low NPSH

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 conditions.
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 embankments.
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

This self-priming pump has an incomparably wide variety of models available for easy selection. Further, a wide variety of materials are available, including FC, SCS and YOKOTA's corrosion and wear resistant special stainless steel casting (YST), to meet the needs of various kinds of liquid.

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.

Stable quality

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 / Principle of self-priming  (PAT.)

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)

Applications

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.

Chemical industry:

Acids, Alkaline liquids, Solvents, Slurry liquids, other

Food industry:

Brewery, Sugar refining, other

Mining industry:

Seawater, Slurry liquids, other

Paper industry:

Pulp, Effluent, White water, Black water, other

Electric power:

Exhaust gas desulfurizer (Limestone slurry pumps, other), Seawater, Water treatment, other

Electronic industry:

Ultra-pure water manufacturing devices, Acidic waste water, Polishing waste water treatment, other

Aquarium, Fish farming:

Seawater suction, Circulation pumps, other

Others:

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

>"Current Topics: Aquarium"

Self-Priming Centrifugal Pump UHN, Used in many aquariums, YOKOTA Seawater Pumps made of YST Alloy

For irrigation pumping stations ... UHN type
Automatic water supply with extremely small tank

>"Current Topics: Irrigation Supply"

Self-Priming Centrifugal Pump UHN, Small tank, but no severe, intermittent operation, YOKOTA Mini-Tank Automatic Water Supply Equipment

For water intake ... Priming strengthened UHNS type
Suction of water through long piping over embankments

>"Current Topics: Snow Removal"

Self-Priming Centrifugal Pump UHN, Excellent for pumping away slush and sprinkling water to melt snow, YOKOTA's snow-fighting pumps

For fish farms ... Priming strengthened UHNK type
Suction of seawater from the sea at a distance of 400m

>"Current Topics: Seawater Intake"

Self-Priming Centrifugal Pump UHN, Resolving the concerns of seawater pumping, YOKOTA Seawater Intake Pump

For power plants ... Slurry resistant UHT type
Resolving problematic self-priming of slurry liquids

>"Current Topics: Slurry Self-Priming"

Self-Priming Centrifugal Pump UHN UHT, Resolving problematic self-priming of slurry liquids at power plants, YOKOTA Slurry/Corrosion Resistant Self-Priming Centrifugal Pump

For undersea tunnels ... Submersible UHPR type
Pumping ensured even if submerged in seawater

>"Current Topics: Undersea Tunnel"

Self-Priming Centrifugal Pump UHN UHPR, Used in draining operation at Kanmon and Seikan Tunnels, YOKOTA pumps and valves


This is a self-priming type pump for suction pumping.
For the non-self-priming type (for force pumping) with similar specifications,
please refer to Centrifugal Pump UEN series.


Structure

UHN type

Self-Priming Centrifugal Pump

Self-Priming Centrifugal Pump

Self-Priming Centrifugal Pump / Nut type
Self-Priming Centrifugal Pump / Cap-nut type
Self-Priming Centrifugal Pump / Shaft-seal type
Nut type
Cap-nut type
Shaft-seal type

Part name Part name Part name Part name
1

Casing

18

Seal ring

27-1

O-ring

39

Sleeve packing

2

Suction cover

191

Impeller nut

28

Impeller key

40

Sleeve key

4

Impeller

192

Impeller nut

29

Coupling key

41

Pan (Option)

6
Liner ring
201

Impeller washer

30

Casing packing

42

Bearing nut

10

Bearing bracket

202

Spring washer

31

Gland bush

43

Bearing washer

11

Front bearing cover

21

Ball bearing

32

O-ring

44

Support ring

12

Rear bearing cover

22

Ball bearing

33

O-ring

47

V-ring

14

Gland

231

Stop ring

35

Oil level gauge

48

O-ring

15

Shaft

232

Stop ring

361

Bearing packing

16

Impeller spacer

25

Gland packing

362

Bearing packing

17

Sleeve

27

Deflector

37

Oil cap



Shaft seal

Gland packing
External flushing type is used for contaminated water
pumping or suction pumping.

Non-External-Flushing Mechanical Seal
No need of external sealing water and applicable to any kind of liquid.

Centrifugal Pump / Gland packing
Centrifugal Pump / Non-external-flushing type

Mechanical seal
Various types of mechanical seals can be installed.

Mechanical seal (oil bath)
Oil-bath lubrication allows dry operation.

Centrifugal Pump / Mechanical seal (self-flushing)
Centrifugal Pump / Mechanical seal (oil bath)

We can also provide double mechanical seals.


Materials
Part name
Material code
F
X
Y
N
R
Casing
FC200
SCS13
SCS14
YST130N
CCR10
Impeller
SCS13
SCS13
SCS14
YST130N
CCR10
Shaft
SUS304
SUS304
SUS316
SUS316
SUS304

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.



UHNS/UHNK types:

Priming strengthened types for intake piping across embankments
or long intake pipes


Type
System/Construction
UHNS

Self-Priming Centrifugal Pump

Water-air separating impeller is installed in the main pump of UHN type to enhance self-priming with vacuum pump.

Self-Priming Centrifugal Pump

UHNK

Self-Priming Centrifugal 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.

Self-Priming Centrifugal Pump



UHT type: 

High corrosion and wear resistance type for high density slurry


Self-Priming Centrifugal Pump The front and rear plates (wear resistant plates) are installed to protect the casing.

Specification:

Economical selections can be made from a wide variety of models similar to the UHN type.

Performance:

Impeller configuration can be selected depending on use.

Material:

A wide variety of materials, such as YOKOTA's corrosion and wear resistant special stainless steel casting (YST), are available.

Construction:

Wear resistant plates are installed for handling high density slurry.

Shaft seal:

Gland packing, mechanical seals and Non-External-Flushing Mechanical Seals can be selected depending on use.



UHPR type: 

Combined with submersible motor for installation in places subject to submersion


Self-Priming Centrifugal Pump UHPR 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.
Self-Priming Centrifugal Pump UHPR


SUH type: 

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.


Selection chart & Outer dimensions

UHN type
Self-Priming Centrifugal Pump
>Selection & Dimensions


UHNS type
Self-Priming Centrifugal Pump
>Selection & Dimensions


Specifications stated here may be subject to change without notice due to product improvement.

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