Yokota Manufacturing Co.
Equipped with hydraulic pressure buffering device
Check valve with buffered closing by-pass valve

[Hiroshima] Yokota Manufacturing Co. (1-3-6 Minami Yoshijima, Naka-ku, Hiroshima, President: Hiroshi Yokota, Tel: 082-241-8672) has developed and released a buffered closing by-pass type check valve (photo) with a hydraulic pressure buffering device (dashpot) for sewer and water supply piping systems. The pricing is from 596,000 yen for the 150mm bore to 13,300,000 yen for the 1,000mm bore.

The check valve prevents counter flow. The non-water hammer type valve prevents shock when counter flow stops instantaneously and pressure increases rapidly, however, the water flow to the by-pass can be controlled slowly via hydraulic pressure due to the built-in dashpot.

The product is characterized by its wide application from low to high pump heads. The dashpot is installed beside the valve case for easy adjustment and maintenance, also, oil control is unnecessary because there is no sealing area on the liquid contact surface.

Featured in news articles as, "Yokota develops check valves with counter flow control device for pumps".

Integrated dashpot
Non-Water Hammer Check Valve
Yokota Manufacturing Co. developed (Hiroshima)

Yokota Manufacturing Co., a specialized manufacturer of pumps and valves (President: Hiroshi Yokota, Hiroshima Tel: 082-241-8672), developed and began sales of a "slow-closure by-pass type check valve equipped with a dashpot". The product integrated a compact dashpot in the non-water hammer check valve which opens and closes according to water volume, and is used at water supply and sewer facilities.

The distinguishing feature of this new product is the prevention of water hammer and shock due to the quick and complete closure of a main valve at the moment water flow in a pipe is reversed from positive flow (the point at which water stops in a pipe), as well as the prevention of pressure build-up after the main valve closes, using the slow-closure by-pass valve. As a result, the product has wide application from low to high pump heads, with ease of use and maintenance.

The main valve is a single-disk of extremely simple construction (built-in counterweight), with added cost reductions possible through compact designing. Moreover, the compact dashpot requires no oil maintenance because there is no seal on the liquid contact side, and thus no oil leakage. The pump can be installed on either vertical or horizontal piping.

Yokota produces a series of valves ranging from a minimum bore of 150mm to the 1000mm large-size bore (Valves manufactured with bores of over 1500mm are also possible), with a manufacturing target of 500 units per year. Pricing on the 150mm-bore valves is 596,000 yen, and 13,300,000 yen for the 1000mm-bore.