They reduce the energy inside the liquid flow
stainless steel sight glass
A variety of valves are utilized in the piping and machinery systems with the ship per the need from the flow pattern on the liquid. All valves utilized on ships contain the basic functionality of governing the flow in the liquid inside pipes.
Valves are widely-used for most machinery systems on ships for controlling and regulating fluid through pipes. Although valves are classified as efficiency decreasing device while they reduce the energy inside the liquid flow, their use is imperative in applications where limited flow becomes necessary.
Slab gate valves such as stainless steel sight glass are comprised of a single gate unit which raises and lowers between two seat rings. Due to the fact which the gate slides relating to the seats, slab gate valves are suitable for the medium with suspended particles. The sealing surface of slab gate valves is virtually self-positioned and is not damaged with the thermal deformation in the body. Even if the valve is closed inside a cold state, the recent elongation from the stem doesn't overload the sealing surface, and slab gate valves without diversion holes undertake and don't high precision within the closing position in the gate. When the valve is fully open, the bore through is smooth and linear, the flow resistance coefficient is minimal, piggable with no pressure loss.
Slab gate valves also provide some disadvantages: if the medium pressure is low, the metal sealing surface may well not seal completely, instead, if your medium pressure is simply too high, the highly-frequency rasing and lowering may make the sealing surface wear a lot of when there is no medium or lubrication. Another drawback is the fact that a circular gate that moves horizontally over a circular channel controls flow effectively as long as it is at 50% in the valve’s closed position.