Which of the following devices is usually operated by compressed air?

The sewage ejector is typically operated by compressed air, which is essential for various processes involved in moving sewage and wastewater from lower to higher elevations. This device relies on air pressure to aid in the efficient transfer of sewage, especially in situations where gravity alone cannot effectively move the waste to its intended destination, such as from a basement to the main sewage line.

Compressed air provides the necessary force to push the waste through the ejector system, ensuring that it can overcome resistance in the pipes and any altitude changes it may need to navigate. The use of air pressure in ejectors also minimizes the risk of blockages and allows for more consistent flow rates.

Other devices like reducers, baffles, and sump pumps do not primarily operate using compressed air. Reducers are typically used to change pipe diameter and do not involve air pressure in their function. Baffles act as barriers to control flow within tanks but do not require compressed air for operation. Sump pumps use an electric motor or a similar mechanism to pump water, reliant on mechanical rather than pneumatic systems. This distinction clarifies the unique role of sewage ejectors in wastewater management.