The story behind the dust collector development

The path to a 75% share of dust collector rentals for tunnel construction

Ever since the development of a dust collector for tunnel construction in 1979, Ryuki Engineering has led the industry for thirty years or more, and pursued its manufacturing and rental business. Our equipment is currently being used in tunnel construction throughout Japan, where we now have a 75% share. The following is a brief explanation of the technology we have developed over the years.

The development of dust collectors for tunnel construction and the reduction in sufferers of pneumoconiosis from tunnel construction work

The development of dust collectors for tunnel construction and the reduction in sufferers of pneumoconiosis from tunnel construction work

In the past, the only methods for tunnel ventilation were to input new air from the outside using a fan or to simply exhaust the inside air outside. This meant that the air inside the tunnel was not very clean.

Many of the workers in this poor environment suffered from "tunnel pneumoconiosis,"and this became a big problem for society, with 1000 tunnel workers or more per year having abnormal medical findings.

However, when the use of large dust collectors spread widely later on, the previously poor work environment was improved dramatically, and the cases of "tunnel pneumoconiosis" were greatly reduced, currently to about 1/100.

Technology refined during years of development work for tunnel construction dust collectors

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Issue 1 High concentrations of dust

There is a very high concentration of inhalable particles(7.07μmand smaller)at the working face (excavation face), at 100mg/m³、with mechanical excavation and 20mg/m³ with excavation using blasting. There is also a high proportion of the harmful crystalline silica, and this was a cause of the tunnel pneumoconiosis.
However, as a result of research and development work, our filter system is able to suck in the high concentration of dust and release the air with a cleanliness level of 0.1mg/m³, which is equivalent to the cleanliness level of the general atmosphere.

Issue 2 Dust which causes easy filter clogging

The dust in tunnels includes consolidated dust, for example from cement and rapid-setting admixture, and also fine particles of diesel carbon exhausted from the heavy machinery. In addition, the harsh environment of high humidity and 24-hour continuous operation are other factors increasing filter clogging. Continuous dust collection was therefore very difficult, but Ryuki Engineering managed to overcome this through our selection of filtersandour work to research and develop the optimal filter cleaning method.

Issue 3 Reduction in equipment size

Ventilation for tunnels requires the processing of large air volumes. However, constraints on the space for installing equipment inside the tunnel and the need for workability meant that the development of compact equipment was essential.
Ryuki Engineering succeeded in producing compact equipment by adopting large surface area pleated filters. Even dust collectors which can process an air volume of 3000 m³ /min can be loaded onto a truck, making it possible to move them around inside the tunnel to respond to the excavation work.

Our dust collectors for tunnel construction work are now in use around the world. We will also continue to apply the technology developed through tunnel construction dust collectors to use in general industry, and aim to manufacture products that can be of use to a wide range of customers.

Our dust collectors for tunnel construction work are now in use around the world.
We will also continue to apply the technology developed through tunnel construction dust collectors to use in general industry, and aim to manufacture products that can be of use to a wide range of customers.

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