SLIDING GATE CONTROL VALVE
The sliding gate valve principle by Schubert & Salzer
This is how easy control can be. Over 30 years ago, Schubert & Salzer Control Systems took a new approach in control valves.
We developed the sliding gate control valve: a handy, light and highly accurate valve. It operates based on a principle that had already excited Leonardo Da Vinci. Even today, it satisfies the most exacting requirements that are placed on a control valve.
The alternative when the demands are high
The sliding gate valve series controls liquid, vapour and gaseous media precisely, quickly and economically. A sealing plate ( 2 ) fixed in the body ( 1 ) at right angles to the flow direction has a certain number of crossways slots ( 3 ) of equal height.
A moving disc ( 4 ) with the same arrangement of slots moves parallely to the fixed disc, thereby changing the flow cross section. The prevailing differential pressure presses the moving disc ( 4 ) against the fixed disc ( 2 ) and seals it.
The advantages of sliding gate valves
Fits into tight spaces: Compact construction for minimum use of space and ease of installation
Outstanding rangeability: 40:1 to 160:1
Easy to install and maintain: Thanks to the compact construction, the low weight (e.g. DN 150 with actuation a mere of approximately 14.2 kg) and the clever seal disc design make light work of installation and maintenance
Variable KVS-values: A simple exchange of the fixed seal is all that‘s needed to change the KVS value at any timepossible range of KVS = 0.018 to 910
Significantly reduced energy consumption: Short stroke requires very little actuation energy
Minimal wear: Related to the effect of the force which is applied at 90° to the direction of flow and minimised by the highly effective pairing of the materials used for the moving and fixed discs
Extremely low leakage rate: < 0.0001% of the KVS value due to the self-lapping action of the moving disc and the pressure of the medium against the moving disc, using a surface seal instead of an annular seal
Optimal flow control: Avoids cavitation problems in the valve and operates quietly by lowering turbulence
Maximum differential pressures: Using its unique compact design and low energy consumption, the GS valve gives accurate control of high differential pressures up to 160 bar
Sliding gate valve – Efficiency
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.
Sliding gate valve – Cavitation
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 valve – Vitality
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.
Sliding gate valve – Weight
Sliding gate valves are significantly „lighter“ than conventional control valves. Thanks to this feature there is no need any pipe works to support it from below. Furhtermore, installation and unistalllation can be done easily
