What is used in a vessel to maintain a certain liquid level?

What is used in a vessel to maintain a certain liquid level?

• A. Weir
• B. Float
• C. Valve
• D. Baffle

Answer: (A)

A weir across the vessel’s outlet maintains a fixed liquid level by overflow. As liquid enters, the level climbs until it reaches the crest of the weir; beyond that point, any extra inflow spills over, so the level stays near the crest height. This provides a simple, passive way to set and hold the liquid level, as long as inflow doesn’t exceed the weir’s overflow capacity. A float is typically a sensing/actuating element for level control, not a standalone method to hold a set level. A valve regulates flow but requires a control system to maintain height. A baffle alters flow patterns or mixing, not the liquid height. So, the device that maintains the liquid level is the weir.

A weir across the vessel’s outlet maintains a fixed liquid level by overflow. As liquid enters, the level climbs until it reaches the crest of the weir; beyond that point, any extra inflow spills over, so the level stays near the crest height. This provides a simple, passive way to set and hold the liquid level, as long as inflow doesn’t exceed the weir’s overflow capacity. A float is typically a sensing/actuating element for level control, not a standalone method to hold a set level. A valve regulates flow but requires a control system to maintain height. A baffle alters flow patterns or mixing, not the liquid height. So, the device that maintains the liquid level is the weir.