Question 90

A pressure vacuum breaker is used for back-siphonage only.

A pressure vacuum breaker is specifically designed to prevent back-siphonage, which occurs when there is a negative pressure in the water supply system that can draw contaminants back into the potable water supply.

A) Back-siphonage only

This option is correct because a pressure vacuum breaker is implemented to protect against back-siphonage. It effectively mitigates the risk of contaminants entering the drinking water supply through negative pressure conditions.

B) Back-pressure only

This option is incorrect as a pressure vacuum breaker does not provide protection against back-pressure. Back-pressure occurs when the pressure in the downstream system exceeds that of the supply, which requires different types of backflow prevention devices.

C) Low hazard only

This option is also incorrect. While a pressure vacuum breaker is suitable for low hazard applications, it is specifically designed for back-siphonage and does not address the broader category of backflow protection that includes back-pressure scenarios.

D) Either back-pressure or back-siphonage

This option is incorrect because a pressure vacuum breaker is not effective against back-pressure. It only serves to prevent back-siphonage, thus making it unsuitable for applications that require protection against back-pressure.

Conclusion

The correct answer, A) Back-siphonage only, highlights the specific function of a pressure vacuum breaker in preventing back-siphonage. The other options fail to recognize that this device is not equipped to handle back-pressure situations, which is crucial for understanding its application in backflow prevention.