Non-External-Flushing Mechanical Seal


Non-External-Flushing Mechanical Seal


Easily fits into a stuffing box and does not require external sealing water

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The YOKOTA Non-External-Flushing Mechanical Seal is a new type mechanical seal which requires no external sealing water supply, being superior in corrosion resistance and wear resistance, and is easily installed into pumps.
This mechanical seal has been adopted for pumps running under severe conditions in industrial fields such as electric power plants, and has been rated highly as an epoch-making mechanical seal.
This mechanical seal is also suitable for seawater and slurry liquid.

Advantages of the YOKOTA Non-External-Flushing Mechanical Seal

Reduction of equipment costs

Piping for external sealing water and electrical instrumentation are not required.

Reduction of running costs

The sealing water cost is not required. (For example, you can save 0.3 litre minute of water which amounts to as much as 150 tons a year.)

The cost for maintaining sealing water in the case of a double mechanical seal or the cost for adjusting leakage in the case of gland packing is eliminated.

Power consumption can be reduced because of the low friction on the sliding surface.

The water imbalance in a plant process due to mixture of sealing water into pumping water can be prevented, and treatment of leaked sealing water is not required.



A comparison of running costs

The cumulative totals of running costs for continuous operation of pumps with a shaft diameter of 48mm and a 30kW motor equipped with a Non-External-Flushing Mechanical Seal, double mechanical seal, or gland packing, are as shown below:

Non-External-Flushing Mechanical Seal / A comparison of running costs


Features

Stable seal performance for a variety of purposes because of the stationary balance type structure.

Easy installation without remodeling a pump casing even when installing to a pump that previously used gland packing.

Malfunctions due to adhesion of slurry, corrosion, or abrasion are not possible because the pins and springs do not contact liquids.

Due to the self-alignment mechanism between its loose ring and rotary ring, the sliding surface of the loose ring floats and efficiently follows the sliding surface of the rotary ring.

Excellent wear resistance to high density slurry liquid because the SiC of the sliding surface has excellent hardness, sliding performance, and corrosion resistance.

YST130N is used for the parts that contact liquids. This is the duplex type stainless steel YOKOTA has developed, and can be used for various liquids because of its remarkable corrosion resistance, wear resistance, and mechanical strength.
(For details of YST130N, please refer to this page.)

Supply of sealing water, such as industrial water, from the outside is not required.
(Please use self-flushing method in order to prevent sliding parts from possible dry-operation caused by a cavity generated within the stuffing box due to generation of negative pressure in the case of self-priming operation, or mixture of air in the case of force pumping operation.)



Structure

Non-External-Flushing Mechanical Seal

Stable seal performance for a variety of purposes because of the stationary balance type structure.

Easy installation without remodeling a pump casing even when installing to a pump that previously used gland packing.

Malfunctions due to adhesion of slurry, corrosion, or abrasion are not possible because the pins and springs do not contact liquids.

Due to the self-alignment mechanism between its loose ring and rotary ring, the sliding surface of the loose ring floats and efficiently follows the sliding surface of the rotary ring.



Performance

Condition of a self-priming limestone slurry pump in an electric power plant after 6 months

Non-External-Flushing Mechanical Seal / Result of operation of a self-priming limestone slurry pump in an electric power plant for 6 months
Pump in operation


Disassembled condition
Limestone slurry sticks to the outside of mechanical seal.

Disassembled condition
Limestone slurry sticks to the inside of stuffing box.

As you can see, there are no problems despite slurry adhesion.


Pump specifications

1.5m3/min x 42m x 1750rpm
Liquid property: Limestone slurry 20wt%
Shaft diameter: 48mm

Running condition

Suction head: -4m
Running period: 6 consecutive months (including 21 stops and starts)

Measurement of abrasion on the seal surface

Seal surface
Amount of abrasion
Rotary ring
0.05mm or less
Loose ring
0.05mm or less
No abnormalities found in the pins and springs of the loose ring.

Coarseness of the seal surface after operation

Non-External-Flushing Mechanical Seal / Roughness of the seal surface after operation

The conditions of the surface coarseness are very good.



Applications

The YOKOTA Non-External-Flushing Mechanical Seal can be used for almost all kinds of liquid. It proves excellent performance especially when used in pumps dealing with the following liquids:

Electricity:

Smoke discharging desulfurizer, Seawater drawing, Waste water treatment, other

Electronics:

Ultra-pure water production, Waste liquid treatment, other

Chemical:

Acid liquid, Alkaline liquid, Solvent, other

Sewage:

Polluted water, Sludge, Liquid containing earth and sand

Others:

Seawater, Condensed seawater, Liquid containing slurry, other

There is detailed information about applications to seawater-related facilities. Please refer to "Current Topics: Aquarium".



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