Fumigation of Grains inside Steel Silos

Infestation inside grain silo is not something which people are not aware of. Infestation does happen inside silo and Fumigation must be carried out to kill pests and insects etc. to save the grains inside silo. Most insects enter grain silos from the top and stay there within 1-2 meters for weeks.

Fumigation is a most essential activity for safe storage of grain inside silo. Grain storage silo must have a properly designed fumigation system.


Phosphine or Hydrogen Phosphide (pH3) is most commonly used fumigant to kill pests in grain silo. Phosphine or Hydrogen Phosphide (pH3) is available in solid form and emits phosphine gas. Phosphine is an inexpensive gas and not an ozone depleting gas, hence considered environmentally safe. Pure phosphine is odorless however due to impurities it smells garlic like or decomposing fish. Phosphine has a density of 1.45 Kg/m3 at 15 DegC. Phosphine gas may self ignite at concentration over 17900 ppm hence it must be handled carefully. Exposure to humans more than 0.3 ppm is not at all advisable. Metals like copper, gold, silver, and brass must not be exposed to phosphine gas as it reacts with them.

Fumigation System

There are various methodologies of grain fumigation inside silo. The most common and economical one is Closed Loop Fumigation system. Closed loop fumigation system consists of Gas Fan, uPVC Pipes, Inlet Outlet Valves and Electronic Gas Monitors. Silos must be properly sealed before initiating fumigation of silos to minimise fumigant leakage during fumigation.

However to have effective fumigation Gas fan, Nos of gas changings per day and uPVC ductings must be sized properly based on size of Silo.

Fumigant Dosage

In order to kill grain pes