What are the two types of vacuum fumigation?

In vacuum fumigation, the process is primarily categorized based on how pressure is managed within the fumigation chamber. The correct answer identifies the two types as Sustained and Restored Pressure.

Sustained pressure fumigation involves maintaining a constant low pressure throughout the fumigation process. This method helps in ensuring that the pest control agent is uniformly distributed and penetrates effectively into the materials being treated. By keeping a steady low pressure, improved efficacy of the fumigant can be achieved.

Restored pressure fumigation, on the other hand, allows fluctuations in pressure during the process, but eventually, the pressure is restored to a desired level post-treatment. This technique can be beneficial in certain situations where changing pressure can enhance the distribution of the fumigant and aid in its penetration into more complex structures.

Understanding these two types helps applicators to choose the appropriate method based on the specific requirements of the fumigation job and the characteristics of the materials being treated, aiming for effective pest control. Options like Continuous and Intermittent or Controlled and Uncontrolled do not accurately capture the intricacies involved in vacuum fumigation practices.