How do pressure/vacuum valves operate in a vapor recovery system?

• A. They enhance the flow of fuel to the pump
• B. They maintain pressure within storage tanks and allow vapor release to the recovery system
• C. They filter out impurities in vapors
• D. They monitor the temperature of the fuel

Answer: (B)

In a vapor recovery system, pressure/vacuum valves play a crucial role in maintaining the integrity of the storage tanks. They are designed to balance the pressure within the tanks by allowing excess vapor to escape when the pressure exceeds a certain threshold and preventing a vacuum from forming when the thermal contraction occurs or when fuel is withdrawn from the tank. This function is vital for preventing the collapse of the tank structure and managing the emissions that might otherwise escape into the atmosphere.

By allowing vapor to be released to the recovery system, these valves help ensure that vapors are safely handled and directed back into the system rather than being released into the environment. This not only complies with environmental regulations but also enhances the efficiency of the vapor recovery system by capturing potentially harmful vapors for reuse.

The other options do not accurately reflect the primary function of pressure/vacuum valves. While they contribute to the overall operation of the fuel system, enhancing fuel flow, filtering vapor impurities, or monitoring temperature are not roles associated with pressure/vacuum valves in the context of vapor recovery systems.