Fumigant Chemistry, Labels, and Safety Data
Fumigant Chemistry, Labels, and Safety Data
This domain tests whether you can predict how a fumigant behaves inside a structure and whether you can read the label and safety data sheet correctly. Florida fumigation exams emphasize sulfuryl fluoride, methyl bromide, phosphine-generating products, and warning agents.
Properties that drive field decisions
- Vapor pressure and boiling point determine how quickly a liquid fumigant volatilizes and how temperature changes the dose.
- Vapor density relative to air tells you where gas accumulates. Sulfuryl fluoride (molecular weight about 102) is roughly 3.5 times as dense as air; methyl bromide (about 95) is about 3.3 times; phosphine (about 34) is slightly heavier than air but mixes readily.
- Odor is not a safety indicator. Sulfuryl fluoride and methyl bromide are essentially odorless; chloropicrin is added as a warning agent. Phosphine has a garlic or fish-like odor, but olfactory fatigue can occur.
- Flammability: phosphine can ignite at high concentrations; sulfuryl fluoride and methyl bromide are nonflammable.
- Reactivity: phosphine products react with moisture to release gas and can corrode metals; never use water on a phosphine spill.
Label versus SDS
The label is the legal use document: rates, sites, PPE, re-entry, and clearance. The SDS explains hazards, first aid, firefighting, and stability; it does not authorize use. Read Section 2 for hazards, Section 5 for firefighting, Section 7 for handling, Section 8 for exposure limits, and Section 10 for reactivity.
Worked example
A technician plans to place a sulfuryl fluoride detector in a single-story house. Because the gas is about 3.5 times heavier than air, it will concentrate in low areas, crawlspaces, and closed rooms. Detectors should be placed low and in each connected space, not only at eye level. If the label requires a reading in the attic, include it because temperature and leakage can create different concentrations there.
Traps
- Treating the SDS as a use label.
- Assuming no odor means no exposure.
- Using water on aluminum phosphide.
- Ignoring temperature effects on vaporization and dosage.
- Placing detectors only at breathing height.
Key points
- The label is law; the SDS is hazard information.
- Vapor density predicts low-area accumulation.
- Odor is not a reliable exposure warning.
- Phosphine reacts with moisture and can ignite.
- Read Sections 2, 5, 7, 8, and 10 of the SDS.