The flexible wedge can be one piece construction - lilyscoggins/ffxivgil GitHub Wiki

Providing a visual indication on the valve position and making it possible to grease the stem. A nut rotates about the threaded stem and moves it. This type is simply suitable for above-ground installation. Non-rising stems are threaded in to the gate, and rotate while using wedge rising and lowering inside steel gate valve. They undertake less vertical space considering that the stem is kept inside the valve body.

AVK offers gate valves  with a factory-mounted indicator for the upper end with the stem to point the valve position. Gate valves with non-rising stems are suited to both above-ground and underground installations.The majority of AVK’s range are made with non-rising stem, but we also offer gate valves with rising stem for water, wastewater and fire protection applications.

By time the upstream velocity involves 0, the disc is very closed. With the reverse flow eliminated, the force essential to produce water hammer on either side on the valve are substantially reduced.Gate valves are primarily created to serve as isolation valves. In service, these valves generally are generally fully open or fully closed. When fully open, the fluid or gas flows over the valve within a straight line with little or no resistance. Gate valves must not be used inside the regulation or throttling of flow because accurate control isn't possible. Furthermore, high-flow velocity in partially opened valves could potentially cause erosion with the discs and seating surfaces. Vibration may also result in chattering in the partially opened valve disc. An exception on the above were created gate valves which might be used for low-velocity throttling; as an example, guillotine gate valves for pulp stock.

The flexible wedge can be one-piece construction such as a solid wedge, but areas behind the seating surfaces are useless to provide flexibility. This construction compensates for adjustments to seat alignment for improved seating whilst the strength of a good wedge at the center. This design offers better leak tightness and improved performance in situations with prospect of thermal binding.The split wedge is made of two-piece construction which seats involving the tapered seats inside valve body.