Tennessee Wastewater Operator Practice Exam

What device protects digester covers from high pressure and vacuum conditions?

1. A pressure sensor

2. A relief valve

3. A gas scrubber

4. A filter membrane

The correct answer is: A relief valve

The device that protects digester covers from high pressure and vacuum conditions is the relief valve. This component is critical in maintaining the safety and integrity of the digester system. As organic materials are processed in a digester, biogas is generated, which can create pressure buildup. A relief valve allows for the safe release of excess pressure, preventing potential structural damage to the digester cover from excessive internal pressure. Similarly, during periods when gas consumption decreases or when the system experiences cooling, a vacuum may form. The relief valve also functions to allow atmospheric pressure to equalize, protecting the digester cover from collapsing or being compromised due to low pressure. In contrast, a pressure sensor is primarily used for monitoring and does not take action to relieve pressure. A gas scrubber treats biogas to remove impurities but does not specifically manage pressure conditions. A filter membrane is used in various separation processes but is not designed for pressure regulation within digesters.