Tennessee Wastewater Operator Practice Exam

How many turns should a gas cylinder valve be opened to ensure it can be quickly closed in an emergency?

1. One quarter turn

2. One half turn

3. One full turn

4. Two full turns

The correct answer is: One quarter turn

To ensure that a gas cylinder valve can be quickly closed in case of an emergency, it is recommended to open the valve only one quarter turn. This practice strikes a balance between allowing enough gas flow for operational needs while enabling rapid closure if an emergency arises. Having the valve opened just a quarter turn means that it can be re-closed swiftly with minimal effort, facilitating quick action during a potential hazard. This limited opening reduces the risk of the valve being inadvertently left open more than necessary, which could pose safety risks. Opening the valve more than one quarter turn increases the complexity and the amount of time it would take to close the valve. Options that suggest a half turn, full turn, or two full turns would not only potentially expose personnel to more gas than necessary, increasing risk, but also make it cumbersome to shut off the gas supply quickly in critical situations. Such operational procedures ensure the safety of workers handling gas cylinders and compliance with safety standards in wastewater treatment facilities.