Snow Removal and Snow Melting
Excellent for pumping away slush and sprinkling water to melt snow ... YOKOTA's snow-fighting pumps (PAT.)
"The train came out of the long tunnel into the snow country..." So begins the famous novel, Snow Country, by Yasunari Kawabata. While the image of a "snow country" where so much snow falls that not a spot of ground is visible is certainly romantic, to those who live there nothing is as troublesome as the snow.
By the way, did you know that if we consider the complete surface area of Japan, half the country can be considered "snow country"?
While there are various protective measures against snow and ice that are taken to protect the lives and livelihoods of those living in "snow country", the greatest number of problems related to snow come from snowfall on railroad tracks and roadways.
One protective measure against snow and ice for railroads and roadways is the "slush removal system" that hydraulically transfers collected snow that has been removed from the railroad tracks or roadways and deposits it in a river. Also, there is the "sprinkler snow melting system" that melts snow by sprinkling water on the road surface.
A large number of pumps are used for these systems. While a normal pump might be sufficient in many cases, under severe conditions that require powerful suction force, such as hydraulically transferring slush with air mixed into it, an ordinary pump would not be able to perform the task.
However, YOKOTA's Self-Priming Centrifugal and Enhanced Self-Priming Pumps can be used for pumping at locations with such severe conditions. Thanks to our unique continuous air-bleeding method (PAT.), difficult pumping situations can be handled with ease.
We will use some actual examples of railroad tracks and roadways to show how the YOKOTA Self-Priming Centrifugal and Enhanced Self-Priming Pumps are utilized.
Railway station F in the Hokuriku region of Japan is located in a ravine, 8.5m below the bottom of a nearby river. Due to this, natural water drainage cannot occur. This is the main reason why the snow-flowing gutters (side-gutters where removed snow flows away) constructed early-on at a large number of stations could not be used here.
In the autumn of 1983, a new "slush-mixture pumping system" for snow removal was installed for the first time throughout Japan.
The system enables snow to be cleared from the tracks by just six people, thereby eliminating the tremendous delays and cancellations of trains due to heavy snowfall. To give an idea of what an advancement this represented, before the implementation of the new system, it would take 50 people using shovels one whole day to clear only the tracks around the switches.
What is the slush-mixture pumping system?
The "slush-mixture pumping system" was developed at the Snow Damage Testing and Research Center of the Niigata Prefecture Science and Technology Agency, and is a system that dumps snow into water, mixes the two into a sherbet-like consistency and then pumps it away through a system of pipes to deposit it at a distant location. It is also known as "hydropower snow transport".
At this station, three separate snow-flowing gutters with a total length of 1.2km were newly installed along the tracks within the station.
Since only 5.2 tons of water per minute can be pumped from the river (due to river management conditions), a water storage tank was incorporated into the snow-flowing gutters and water previously suctioned from the river is held in this tank. By combining the 10 tons of water supplied from the water tank with 5.2 tons from the river, 15.2 tons per minute can be supplied to any one of the three snow-flowing gutters.
Snow on the tracks is suctioned up by a rotary snow removal train and deposited in the snow-flowing gutters. This snow is guided to the rotating screw in the slush mixing unit where it is finely ground.
It is then passed through a grated filter and the sherbet-like slush is pumped away through steel piping along the tracks to a discharge outlet located on a river approximately 900m away. 5.2 tons of water and 1.05 tons of snow come gushing out of the discharge outlet every minute. The remaining water that passes through the filter is circulated back into the water storage tank.
Why use YOKOTA pumps?
The two main pumping jobs for this snow removal system require an "intake pump" to suction water from the river and deliver it to the system, and a "slush transport pump" to pump the slush mixture (made from the river water and the removed snow) to the discharge point on the river.
A regular pump cannot possibly offer the capabilities, as listed below, required of these pumps.
Therefore, YOKOTA Self-Priming Centrifugal and Enhanced Self-Priming Pumps have been selected since they possess the capabilities required to satisfy these strenuous requirements.
Furthermore, YOKOTA's Non-Water Hammer Check Valve has been adopted for these pumps to prevent water hammer when the pump is stopped and ensure stable pumping.
YOKOTA Self-Priming Centrifugal Pump UHNS type (PAT.) used for water intake ... Self-priming even with extended lengths of suction piping
The YOKOTA Self-Priming Centrifugal Pump UHNS type was chosen for the intake pump because it can handle the rigorous suction requirements of extended lengths of suction piping that goes up and over embankments.
The Self-Priming Centrifugal Pump with a strong self-priming capability is used as the main pump and is supplemented by a vacuum pump to further increase self-priming capability and reduce self-priming time. Also, a water-air separating impeller is installed between the main and vacuum pumps to provide our patented "continuous air-bleeding mechanism" that prevents water or mud from entering the vacuum pump.
Since the main pump possesses its own self-priming capability, the vacuum pump can be stopped under normal conditions.
YOKOTA Enhanced Self-Priming Pump UPS type (PAT.) used for slush transport ... Discharges air while pumping
The YOKOTA Enhanced Self-Priming Pump UPS type with a non-clogging impeller was selected for the slush transport pump that is the central heart of this snow removal system.
The sherbet-like slush ground by the mixing unit contains 30% to 40% air, and is in a state of "multiphase flow", i.e., air-solid-liquid mixture.
A regular pump attempting to suction this slush would suffer a loss of pumping capacity or pump stoppage. However, the YOKOTA Enhanced Self-Priming Pump has a vacuum pump that operates constantly, removing air from the mixture to ensure constant and stable pumping. Also, slush cannot enter the vacuum pump due to the operation of the water-air separating impeller.
YOKOTA Enhanced Self-Priming Pump mechanism (PAT.)
Accordingly, incoming air does not block the pump suction inlet or main impeller since the suction side is always operated under the vacuum pump's maximum vacuum and bleed amount conditions. This results in stable, high-level pump performance.
Moreover, because the movement of the water-air separating impeller prevents penetration of mud, sand, and earth in the vacuum pump, pumping efficiency is ensured and safe.
The "sprinkler snow melting system" is simply a method to melt snow by sprinkling water on the roadway. As shown in the figure above, it consists of a pump that intakes water and supplies it to the sprinklers where the water is sprinkled onto the road surface via the nozzles.
While various types of water, such as ground, river, sea, or hot springs water, can be used, conventional systems mainly used groundwater. But, since suctioning out too much groundwater can result in a lower water level or ground sinkage, the use of river water has recently been gaining prominence as a way to avoid these problems.
The main economic activities of Town K in Shiga Prefecture are agriculture and forestry-related. It snows 33 days out of the year and yearly snowfall is 290mm.
A sprinkler snow melting system was first introduced in this town in 1977. From that time until 1991, the system grew to consist of intake pumps in 15 locations and a snow melting pipe network with a total length of 9km. Of these 15 locations, the YOKOTA Totally Waterproof Self-Priming Centrifugal Pump System is installed in 3 locations for river water intake.
The main economic activity of Town K in Tottori Prefecture consists of pear trees, grape orchards, and other fruit farming. It snows 50 days out of the year and yearly snowfall is 900mm.
A sprinkler snow melting system was first introduced in this town in 1981. From that time until 1991, the system grew to consist of 11 sprinkling locations and a snow melting pipe network with a total length of 7.4km. The YOKOTA Totally Waterproof Self-Priming Centrifugal Pump System is also installed here in one of the locations for river water intake.
While these pumps intake river water, there are nearby river water irrigation channels for agricultural use that are not used during the winter from which water is drawn. However, since the water level is reduced in the winter, a cylindrical-shaped rubber balloon ("rubber dam") is used to block and store water, as shown in the figure, which can then be pumped out. Then, in spring, when the water is needed for agricultural purposes, the dam is deflated so that the water can be utilized accordingly.
Why use YOKOTA pumps?
While submersible or horizontal centrifugal pumps are normally used for groundwater or river water intake, they have the following disadvantages:
However, all of these problems can be easily resolved by using the YOKOTA Totally Waterproof Self-Priming Centrifugal Pump System.
YOKOTA Totally Waterproof Self-Priming Centrifugal Pump System (PAT.) used for water intake ... Self-priming system operates easily, even underwater
Advantages of the YOKOTA Totally Waterproof Self-Priming Centrifugal Pump System
In other words, the YOKOTA Totally Waterproof Self-Priming Centrifugal Pump System can be situated underground for hands-free operation due to it being submersible (completely waterproof) and capable of handling air mixed into pumped liquid (complete air-bleeding type). This pump system has been adopted based on its reputation for convenience.
With the addition of the Non-Water Hammer Check Valve and No-Feed Detector to the interlocked Self-Priming Centrifugal Pump UHPR type (main pump) and vacuum pump with submersible motors, the system offers completely automatic operation.
When the main and vacuum pumps are operated simultaneously, pumped water tends to flow toward the vacuum pump. With regular vacuum pumps, mud mixed in with the pumping liquid may cause a malfunction, but the air-bleeding system (PAT.) of the YOKOTA Vacuum Pump includes a water-air separating impeller (7), installed in front of the vacuum pump impeller (6), that separates water, mud, and other substances, returning them to the suction side so that only air is discharged to the outside.
The vacuum pump, protected by this structure, is able to rapidly discharge even large amounts of air so that the main pump is not stopped and continuous pumping operation is possible.
This allows completely hands-off operation capability and is a major advantage of the YOKOTA Vacuum Pump.
Regarding the YOKOTA Non-Water Hammer Check Valve (PAT.)
All of the above-mentioned pumps are equipped with YOKOTA Non-Water Hammer Check Valves for safe pumping.
For details of each product, please refer to
Self-Priming Centrifugal Pump UHN series (UHNS, UHPR types)
Enhanced Self-Priming Pump UPM, UPS types
Non-Water Hammer Check Valve SL series