In oil tanks without a constant oil level maintained by __________, what must be equipped to determine the oil level?

The context of this question revolves around managing the oil level in tanks, particularly when there isn’t a constant oil level maintained by a specific system. An automatic pump is essential in this scenario because it actively manages the oil level by pumping oil in or out as needed. Without a constant oil level, relying solely on passive measures can lead to either overflow or depletion of the oil supply, which can impair operations or cause unsafe conditions.

The role of an automatic pump is to monitor the oil level and adjust it in real-time, ensuring that the tank maintains a safe and functional level of oil. This automation reduces the need for manual monitoring and intervention, which can be prone to human error and could delay necessary actions in critical situations.

Other options such as a manual gauge or a sight glass are useful for indicating oil level but do not have the capability to control or maintain that level. A float switch, while it can alert to changes in oil level, does not actively manage the oil level by moving oil in or out of the tank. Therefore, an automatic pump is the correct and effective solution when a constant oil level cannot be maintained.