The device used to vent air into an anaerobic digester to prevent vacuum is called:

The device used to vent air into an anaerobic digester to prevent vacuum is called:

• A. Vacuum breaker
• B. Pressure relief valve
• C. Float valve
• D. Bypass valve

Answer: (A)

Air inside an anaerobic digester can pull a vacuum as gas volume changes, so something must let air in to keep pressure from dropping below atmospheric. A vacuum breaker is a venting device that opens when the pressure goes negative and allows ambient air to enter the system, preventing the vacuum from forming. It protects the digester shell and piping from damage and keeps operation stable by maintaining proper pressure balance. The other devices serve different roles: a pressure relief valve opens when the system is over-pressurized, not to prevent vacuum; a float valve controls liquid level, not venting; a bypass valve redirects flow and isn’t used to vent air into the digester.

Air inside an anaerobic digester can pull a vacuum as gas volume changes, so something must let air in to keep pressure from dropping below atmospheric. A vacuum breaker is a venting device that opens when the pressure goes negative and allows ambient air to enter the system, preventing the vacuum from forming. It protects the digester shell and piping from damage and keeps operation stable by maintaining proper pressure balance.

The other devices serve different roles: a pressure relief valve opens when the system is over-pressurized, not to prevent vacuum; a float valve controls liquid level, not venting; a bypass valve redirects flow and isn’t used to vent air into the digester.