Most fumigants can achieve the same insecticidal effect by maintaining a short time at a high concentration or a long time at a low concentration. The two major factors for determining the insecticidal effect are the effective concentration and the effective concentration maintenance time. The increase in the concentration of the agent means an increase in the cost of fumigation, which is economical and effective. Therefore, extending the fumigation time as much as possible is an effective way to reduce the fumigation cost and maintain the insecticidal effect.
The fumigation operating procedures stipulate that the air tightness of the warehouse is measured by half-life, and the time for the pressure to drop from 500Pa to 250Pa is ≥40s for flat warehouses and ≥60s for shallow round warehouses to meet the fumigation requirements. However, the air tightness of the warehouses of some storage companies is relatively poor, and it is difficult to meet the air tightness requirements of fumigation. The phenomenon of poor insecticidal effect often occurs during the fumigation process of stored grain. Therefore, according to the air tightness of different warehouses, if the optimal concentration of the agent is selected, it can both ensure the insecticidal effect and reduce the cost of the agent, which is an urgent problem to be solved for all fumigation operations. To maintain the effective time, the warehouse needs to have good air tightness, so what is the relationship between air tightness and agent concentration?
According to relevant reports, when the air tightness of the warehouse reaches 188s, the longest concentration half-life of sulfuryl fluoride is less than 10d; when the air tightness of the warehouse is 53s, the longest concentration half-life of sulfuryl fluoride is less than 5d; when the air tightness of the warehouse is 46s, the shortest half-life of the longest concentration of sulfuryl fluoride is only 2d. During the fumigation process, the higher the sulfuryl fluoride concentration, the faster the decay, and the decay rate of sulfuryl fluoride gas is faster than that of phosphine gas. Sulfuryl fluoride has a stronger permeability than phosphine, resulting in a shorter gas concentration half-life than phosphine.
Sulfuryl fluoride fumigation has the characteristics of rapid insecticide. The lethal concentration of several major stored grain pests such as long-horned flat grain beetles, saw-saw grain beetles, corn weevils, and book lice for 48h fumigation is between 2.0~5.0g/m’. Therefore, during the fumigation process, the sulfuryl fluoride concentration should be reasonably selected according to the insect species in the warehouse, and the goal of rapid insecticide can be achieved.
There are many factors that affect the decay rate of sulfuryl fluoride gas concentration in the warehouse. The air tightness of the warehouse is the main factor, but it is also related to factors such as grain type, impurities, and porosity of the grain pile.
Post time: Jul-15-2025
