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Self-Priming Centrifugal Pump
UHN series (PAT.)
Outstanding self-priming performance even under extreme conditions
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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.
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For suction pumping with outstanding self-priming power:
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UHN type
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For intake piping across embankments or long intake pipes:
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Priming strengthened UHNS/UHNK types
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For high density slurry:
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Slurry resistant UHT type
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For installation in places subject to submersion:
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UHPR type with submersible motor
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For self-priming sanitary specifications:
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SUH type
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Features of the YOKOTA Self-Priming Centrifugal Pump
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Outstanding self-priming power
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The internationally patented water-air separating mechanism reaches a maximum
vacuum of 60-90kPa (6-9m water column) and displays outstanding self-priming
power.
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No problem with suction of air during pumping
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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.
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Low NPSH
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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.
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Simple structure without any inlet valve, No need for a foot valve
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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.
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Intake piping across embankments or long intake piping is possible
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Because of superior intake power, intake pipes can be installed across
embankments.
Intake piping with long piping is also possible.
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Outstanding pumping performance
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This single-suction, single-stage centrifugal pump displays outstanding
pumping performance in a wide range of specifications.
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Large selection of models, Large selection of materials
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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.
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Construction that can meet a wide range of specifications
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Standard constructions include semi-open impellers for small pumps and
closed impellers for medium and larger pumps.
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The impeller has been improved to form ideal blades for high efficiency.
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An oil bath lubrication system is adopted for bearings.
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Maintenance is easy to perform because construction is simple and the number
of parts in the water passage section is minimized.
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Stable quality
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All special material products are manufactured internally in a continuous
process to ensure stable quality.
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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. |
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1. Flow of circulation
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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.
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2. Removal of bubbles
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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.
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3. Water-air separation and exhaust
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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.
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| Self-Priming Centrifugal Pump UHN series |
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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) |
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Applications
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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.
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Chemical industry:
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Acids, Alkaline liquids, Solvents, Slurry liquids, other
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Food industry:
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Brewery, Sugar refining, other
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Mining industry:
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Seawater, Slurry liquids, other
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Paper industry:
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Pulp, Effluent, White water, Black water, other
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Electric power:
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Exhaust gas desulfurizer (Limestone slurry pumps, other), Seawater, Water
treatment, other
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Electronic industry:
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Ultra-pure water manufacturing devices, Acidic waste water, Polishing waste
water treatment, other
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Aquarium, Fish farming:
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Seawater suction, Circulation pumps, other
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Others:
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Hot springs, Hot oil, other
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Example applications and installations (Special cases where difficult pumping conditions are present)
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For aquariums ... UHN type
Made of extraordinary seawater resistant YST alloy
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For irrigation pumping stations ... UHN type
Automatic water supply with extremely small tank
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For water intake ... Priming strengthened UHNS type
Suction of water through long piping over embankments
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For fish farms ... Priming strengthened UHNK type
Suction of seawater from the sea at a distance of 400m
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For power plants ... Slurry resistant UHT type
Resolving problematic self-priming of slurry liquids
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For undersea tunnels ... Submersible UHPR type
Pumping ensured even if submerged in seawater
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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.
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Structure
UHN type
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Nut type
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Cap-nut type
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Shaft-seal type
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| Part name |
Part name |
Part name |
Part name |
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1
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Casing
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18
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Seal ring
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27-1
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O-ring
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39
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Sleeve packing
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2
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Suction cover
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191
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Impeller nut
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28
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Impeller key
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40
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Sleeve key
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4
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Impeller
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192
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Impeller nut
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29
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Coupling key
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41
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Pan (Option)
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6
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Liner ring |
201
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Impeller washer
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30
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Casing packing
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42
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Bearing nut
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10
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Bearing bracket
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202
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Spring washer
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31
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Gland bush
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43
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Bearing washer
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11
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Front bearing cover
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21
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Ball bearing
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32
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O-ring
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44
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Support ring
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12
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Rear bearing cover
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22
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Ball bearing
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33
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O-ring
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47
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V-ring
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14
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Gland
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231
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Stop ring
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35
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Oil level gauge
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48
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O-ring
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15
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Shaft
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232
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Stop ring
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361
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Bearing packing
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16
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Impeller spacer
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25
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Gland packing
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362
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Bearing packing
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17
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Sleeve
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27
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Deflector
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37
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Oil cap
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Shaft seal
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Gland packing
External flushing type is used for contaminated water
pumping or suction pumping.
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Non-External-Flushing Mechanical Seal
No need of external sealing water and applicable to any kind of liquid.
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Mechanical seal
Various types of mechanical seals can be installed.
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Mechanical seal (oil bath)
Oil-bath lubrication allows dry operation.
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We can also provide double mechanical seals.
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Materials
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Part name
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Material code
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F
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X
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Y
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N
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R
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Casing
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FC200
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SCS13
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SCS14
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YST130N
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CCR10
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Impeller
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SCS13
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SCS13
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SCS14
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YST130N
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CCR10
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Shaft
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SUS304
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SUS304
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SUS316
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SUS316
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SUS304
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Special material products are manufactured internally in a thoroughly continuous
process from casting under complete material and heat-treatment control.
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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.
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UHNS/UHNK types:
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Priming strengthened types for intake piping across embankments
or long intake pipes
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Type
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System/Construction
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UHNS
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Water-air separating impeller is installed in the main pump of UHN type
to enhance self-priming with vacuum pump. |
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UHNK
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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. |
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UHT type:
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High corrosion and wear resistance type for high density slurry
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The front and rear plates (wear resistant plates) are installed to protect
the casing. |
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Specification:
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Economical selections can be made from a wide variety of models similar
to the UHN type.
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Performance:
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Impeller configuration can be selected depending on use.
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Material:
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A wide variety of materials, such as YOKOTA's corrosion and wear resistant
special stainless steel casting (YST), are available.
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Construction:
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Wear resistant plates are installed for handling high density slurry.
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Shaft seal:
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Gland packing, mechanical seals and Non-External-Flushing Mechanical Seals
can be selected depending on use.
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UHPR type:
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Combined with submersible motor for installation in places subject to submersion
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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. |
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SUH type:
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High washability self-priming sanitary pump
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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. |
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Selection chart & Outer dimensions
Specifications stated here may be subject to change without notice due
to product improvement.
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