Fast - innovative - precise. The valve for highest demands.
The sliding gate valves are characterised by a special throttle device in the functional unit that merely comprises two slotted disks that slide over each other and seal against each other. One sealing disc that is fitted in the housing perpendicular to the direction of flow has a predefined number of transverse slots. The second disc that is torque-proof and has the same arrangement of slots is moved perpendicular to the other one, this thereby changing the flow cross-section. The applied pressure differential presses the movable disc against the stationary disc.
The outstanding feature of the sliding gate valve is the actuating force which is about just 10% of that needed to actuate a globe valve of the same nominal size and the same differential pressure. This permits the use of much smaller actuators even though both designs of the same nominal size have about the same flow rate! This beneficial feature stems from the fact that, in the sliding gate valve, closure is trans- verse to the direction of flow and not against it, as with the globe valve.
A high rate of flow through the narrowest cross section of a valve will lower the local pressure below the vapour pressure of the liquid. Vapour bubbles form which then collapse in the regions of higher pressure. When they come into contact with solid boundaries (valve body), the imploding bubbles can cause damage. In the case of a sliding gate valve, these dangerous cavitation zones are external, or more accurately, they are located about 1 - 2 m beyond the valve. The cavitation bubbles then collapse around the centre of the pipeline where they can cause no harm.
Sliding gate valves are significantly „faster“ than conventional control valves. This can be shown using the frequency response when the set point value to an installed positioner is taken as the input value and the resulting stroke amplitude as the output value. The progression of the frequency response affects the standard of control of the entire control circuit.
The low actuating force and short stroke allow the use of smaller actuators. Coupled with the space-saving wafer construction, weight and in-stallation dimensions are minimised, particularly in the mid to large nominal sizes. This translates into about 150 kg for a seat globe valve in DN 150, whereas a sliding gate valve of the same nominal size weighs a mere 15 kg!