| Fumigation Procedures |
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| Vertical silo bins |
| 01. Check ventilation for silo basement and tunnels. |
| 02. Calculate total quantities of tablets or pellets required on the basis of : |
| (a) Capacity of commodity to be treated; |
| (b) Average filling capacity per hour; |
| (c) Total time required to fill each bin; |
| (d) Average temperature and humidity inside the bin; |
| (e) Type of pests. |
| 03. If using the automatic dispenser, check voltage and current. |
| 04. Tablets may be thrown by hand through a manhole or dropped on the conveyor belt at regular intervals as the commodity is fed into the bin. |
| 05. The working space should be well-ventilated during the throwing in operation. Tightly close the opening afterwards. |
| 06. Stick warning notices prominently. Do not permit anyone to enter the fumigated or neighboring bins during the period of exposure. |
| 07. Do not transfer the contents to other bins during the fumigation period. |
| 08. After fumigation period is over, a safety check with a gas detector is essential before workers enter the area. |
| 09. Recommended dosage 3-5 tablets per metric tonne with minimum exposure period of 3 days. Aeration: 6 hours. |
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| Conventional storage |
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| 01. Foodgrains in gunny bags are stacked properly inside the godown or to a convenient height on a wooden platform in the open air, as per the prevailing practices. |
| 02. Calculate the total number of tablets required for fumigation of the stock. |
| 03. Spread non-porus plastic sheet or rubberized sheet above the stock so that it can be pulled down to cover the sides immediately after distributing the tablets. |
| 04. Distribute the tablets all over the stock preferably by using a tray, so that the residue can be disposed off easily. |
| 05. Pull down the sheet on all sides & seal the edges air tight by using sand sacks or weights. |
| 06. Post prominent warning notices all around the fumigated area. |
| 07. Periodically check for leakages, if any. |
| 08. After fumigation is complete ventilate the stocks carefully, by partially opening the sheet. |
| 09. Dosage of 3-5 tablets per metric tonne with an exposure period of 3 days is recommended. Aeration : Minimum of 6 hours. |
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| Flat storage |
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| 01. Check the storage for gas tightness and commodity temperature. |
| 02. Use a fumigation probe for better penetration of tablets/ pellets. |
| 03. Calculate in advance total number of tablets/ pellets required. Divide them in equal numbers to number of probings. |
| 04. Keep doors and windows open during probing operation. |
| 05. Insert probe horizontally at 3 to 4 feet intervals. Let it sink as deeply as possible into the layer of grain. The tablets/ pellets are ejected into the grain as the probe is withdrawn. |
| 06. Hot spots (insect attacks confined to small areas) can be similarly treated by the probe method. |
| 07. Keep a gas detector handy to detect the presence of hydrogen phosphide. |
| 08. When fumigating grain stored in different parts of the building, start from the top floor. The time taken for the entire building should not exceed four hours. |
| 09. Cover the grain mass with impervious plastic sheets or tarpaulins immediately after the tablet distribution is over. |
| 10. Close and seal all doors, windows and hatches. |
| 11. Stick warning notices at all entrances. |
| 12. Evacuate adjoining rooms and buildings of inhabitants and pets during the entire fumigation operation. |
| 13. After the exposure time, remove sheets or tarpaulins, starting from the inner part of warehouse towards the door. Operators should wear gas masks. |
| 14. Air the commodity for a few days following fumigation. |
| 15. Dosage of 3-5 tablets per metric tonne with an exposure period of 3 days is recommended. Aeration : Minimum of 6 hours. |
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| Rail wagons, trucks, ships, barges |
| 01. These are treated in much the same way as floor stored commodities. Scatter tablets evenly on the floor before loading, or put them in trays, or on top of the product, or by probing. |
| 02. Do not fumigate if commodity temperature remains below 5 degree celsius (40 F) as this could result in incomplete kill. |
| 03. Holds in ships should be absolutely gas-tight. All living quarters should be evacuated. |
| 04. Use plastic sheeting for sealing after distributing tablets. Secure it tightly with hooks, weights etc. Cover with tarpaulin as an added protection against bad weather. |
| 05. Stick warning notices outside. |
| 06. Dosage of 3-5 tablets per metric tonne is recommended. Period for exposure : 72-96 hours. Aeration : 6 hours. |
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| Tobacco in cases, Bales or Hogheads |
| 01. Keep dosage low, as tobacco is a very sensitive product and the flavour may be impaired. |
| 02. It is advisable to conduct test fumigation with small lots before undertaking a full scale fumigation. |
| 03. Beware of electrical equipment, as phosphine reacts adversely to copper compounds, silver and gold. Coat the switch boxes with liquid paraffin. |
| 04. When fumigating stacked tobacco, distribute tablets on sheets around or beneath stacks, then cover completely with gas-tight plastic sheets. |
| 05. Recommended period for exposure: 8-10 days. Aeration: 10-12 hours. |
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| Packed commodities and processed foods |
| 01. Cover the stack of packages with non-porous plastic sheets. |
| 02. Make sure that packed commodities are not in direct contact with the tablets. |
| 03. Place tablets on ground or on trays around the stacks of commodities. Tablets should not touch each other. |
| 04. Seal the edges of plastic sheets tightly with tape. Put weights if necessary. |
| 05. Workers need not vacate the building in case of a secure seal and proper ventilation. |
| 06. Stick warning notices on all four sides of the stacks. |
| 07. After fumigation is over, collect tablet residue and dispose it off as per instructions given. |
| 08. Recommended dosage is around 45 tablets per 1000 cubic feet. Minimum exposure period of 72 hours and an aeration period of 8-10 hours. |
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| Flour mills and warehouses |
| 01. Seal the enclosure to be fumigated. |
| 02. Calculate dosage in advance based on (a) volume of structure to be fumigated; (b) Temperature of commodity; (d) Tightness of structure to be fumigated. |
| 03. Spread the tablets or pellets on trays, sheets or aluminium foil, as it is easier later on to collect the dust residue. |
| 04. Put warning notices on doors immediately after operation. |
| 05. If necessary, notify the fire department and the police before start of operation. |
| 06. Open all doors and windows after exposure time. Water gas mask to enter the enclosure. |
| 07. Check the absence of gas with a gas detector before entering the enclosure. |
| 08. Recommended dosage is 20 tablets per 1000 cubic feet. Period for exposure: one day. Aeration : A minimum of 6 hours. |
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| Note: Dosage rates & exposure periods mentioned above are average. In some cases higher or lower dosage may be needed depending on temperature and humidity conditions. |
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