What is a gate (sluice) valve?
Gate valves are used in a wide variety of applications, suited for both above-ground and below-ground installations. For below-ground installations especially, it is crucial to select the appropriate valve to avoid costly replacements.
Where are gate (sluice) valves used?
Gate valves are commonly used where minimum pressure loss and a free bore is needed. When the valve is fully open, a typical gate valve has no obstruction in the flow path resulting in a very low pressure loss, and this design makes it possible to use a pipe-cleaning pig. Gate valves are classified as multiturn valves, requiring multiple rotations of the stem to go from fully open to fully closed, which also helps reduce water hammer risk.
AVK's gate valves can be used across a wide range of fluids, with the following working conditions:
- Potable water, wastewater and neutral liquids: temperature between -20 and +70 °C, maximum 5 m/s flow velocity and up to 16 bar differential pressure.
- Gas: temperature between -20 and +60 °C, maximum 20 m/s flow velocity and up to 16 bar differential pressure.
See AVK’s installation and maintenance instruction for water/wastewater and gas.
Gate (sluice) valves with by-pass
By-pass valves serve several important functions:
- To allow the pipeline differential pressure to be balanced, lowering the torque requirement of the valve and permit one-man operation
- With the main valve closed and the by-pass open, a continual flow is allowed, avoiding possible stagnation
- Delayed filling of pipelines
AVK offers gate valves with by-pass in dimensions from DN 450, see series 55/30 and 06/30.
Parallel vs wedge-shaped gate (sluice) valves
Gate valves are categorized into two main types: Parallel and wedge-shaped. The parallel gate valves use a flat gate between two parallel seats, and a popular type is the knife gate valve designed with a sharp edge on the bottom of the gate. Wedge-shaped valves, on the other hand, are designed with two inclined seats and a slightly mismatched inclined gate.
Most of AVK's gate valves are of the solid wedge-shaped design, but we also offer knife gate valves for wastewater treatment and parallel slide valves for gas supply.
Metal seated vs resilient seated gate (sluice) valves
Before the introduction of resilient-seated gate valves, metal-seated designs were the standard. These older models required a sump at the valve bottom to ensure a proper seal, but over time, impurities such as sand could prevent the valve from sealing tightly. Conversely, resilient-seated gate valves have a flat bottom, allowing debris to pass through freely. High-quality rubber in these valves absorbs impurities during closure and flushes them away when reopened, ensuring tight sealing.
While AVK primarily produces resilient-seated gate valves, we continue to offer metal-seated versions for certain markets and in dimensions larger than DN1200.
Rising vs non-rising stem design
Rising stem gate valves have a stem that moves with the gate, providing a visual indication of the valve’s position and enabling easy lubrication of the stem. These are typically suitable for above-ground installations. Non-rising stem gate valves, where the stem remains within the valve body while the gate moves internally, are more compact and take up less vertical space. They are suitable for both above-ground and underground installations.Most AVK gate valves feature a non-rising stem design, but we also offer rising stem models for water, wastewater, and fire protection applications.
