The special valve plug structure removes dust adhering to the seat surface (valve seat) when the valve is opened and closed. For this reason, this valve is widely used for blast furnace gas (BFG), coke oven gas (COG), and converter gas (LDG), which are byproduct gases generated in steel mill facilities with a lot of dust.
Excellent blocking characteristics
The sealing ring is strongly pressed onto the seat surface to completely shut off gas with no leakage. To further ensure safety, it can also be used as a water-sealing valve.
The “double-closed structure” with independent valve plates on both the gas inlet and outlet sides is extremely safe.
No friction at the seal (seal ring)
The friction at the sealing portion, which is the weak point of butterfly valves, is eliminated by a mechanism that independently performs the valve plate turning movement and the loosening/closing movement.
This reduces friction in the sealing area and prevents deterioration of the gas shutoff performance even after repeated opening and closing operations.
Response to double blocking
The use of the NK valve will make it easier to install a downstream closure flange for the double shutoffs that are currently being promoted, and will facilitate efforts to achieve a complete double shutoff.
Low pressure loss
The valve body (valve box) is spherical in shape, which allows a large gas passage area, smooth flow, and low pressure loss.
Fewer failures and longer service life
We have a track record of delivery to steel mills nationwide, and some of our valves have been in service for more than 50 years with few breakdowns and overhauls.
Compact, lightweight and easy to install
When used as a water-sealing valve, it does not require a large space for installation like a V-shaped water-sealing pipe, and the amount of water required for water sealing is small, making it environmentally friendly and simplifying the foundation, etc.
opening and shutting operation
The NK valve has a double-closing structure with two valve plates, one on the inlet side and the other on the outlet side, pressed against their respective seat surfaces. The closed state is controlled by the force that presses the seal ring against the valve seat (torque seat method) for reliable gas shutoff.
After the two valve plates are pulled in toward the center from the seat surface, the valve is fully opened by turning it 90° around the valve stem (the valve plates are at right angles to the inlet and outlet ports).
Turn the two valve plates 90° around the valve stem in the direction of the inlet and outlet ports. Then, they are moved in the direction of pressing against the seat surface to evenly crimp the sealing ring against the seat surface to shut off gas.
There is no interference between the seat surface and the seal ring during valve opening and closing operations, and this structure does not cause damage to the seal ring or operation failure due to dust adhesion.
In addition, the valve plate peels off dust adhering to the seat surface during turning.
About Gas Shutoff
Currently, valves from other manufacturers and V-shaped water-sealing pipes are sometimes used as complete shutoff valves in steel mills.
The V-shaped water-sealing pipe requires another valve on the upstream side, which cannot be used in an emergency because of the long water tensioning time, requires a large space for installation, and is heavy due to the large amount of water sealed, which has the disadvantage of requiring a huge cost for the foundation.
The NK valve can be operated as an emergency gas shutoff valve without water sealing by itself because of its excellent gas sealing performance due to its double-closed structure.
If necessary, the inside of the valve can be filled with water to complete water sealing using only the NK valve, further increasing safety.
Compared to a V-shaped water seal pipe, the valve can be filled with water with a smaller amount of water, thus enabling water sealing in a shorter time and with less weight.
|Nominal diameters larger than those shown on the left can also be manufactured, so please contact us.
|Higher pressures than those listed on the left can also be manufactured, so please contact us.
|Differential pressure at valve opening/closing
|Higher differential pressures than those shown on the left can also be manufactured, so please contact us.
|Seal ring material
|Viton・NBR・CR・Heat-resistant lattice mesh packing