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  1. Sulphuryl fluoride

Sulphuryl fluoride has been developed as an effective fumigant for controlling dry wood termites. This gas has outstanding dispersion and penetrating qualities which permit it to infiltrate termite tunnels and crevices and destroy the insects. Sulphuryl fluoride does not escape through plastic sheets used in structural fumigation as rapidly as methyl bromide or other organic fumigants. Because this gas is odourless, chloropicrin, discharged separately, is recommended as a warning agent.

Description

 

Common Name:

Sulphuryl fluoride

Chemical Name:

Sulphuryl fluoride

Chemical formula:

SO2F2

Physical Properties  
State:

Odourless & Colourless Gas

Odour:

None

Boiling Point :

-55.2°C              

Freezing Point : Molecular Weight:

   102.06

 

Specific gravity:

i) At gaseous stage :

2.88

Melting Point:

-120°C

ii) At liquid stage :

1.342 at 4°C

Latent Heat of Vapourisation:

79.5 BTU/lb at -55.2°C

Flammability           :

Nonflammable

Solubility in water:

0.075 g/100 g at 25°C

Chemical Properties

Non-corrosive, relatively unreactive and harmless to wide variety of household materials

Relation between weight and volume of Liquid:

Weight Volume

1 lb.  =

338 ml (4°C or 39.2°F)

1 Kg. =

745.1 ml

1.342 Kg. =

1 litre
Relation between dosages and concentration of Gas in air

By volume Weight per volume
Parts per million Percent ¹g/m³ lb/l 000 ft³
25 0.0005 0.0228
20 0.002 0.091
50 0.005 0.228
100 0.01 0.456
200 0.02 0.91
239.6 0.024 1.00 0.062
500 0.05 2.278 0.142
1 000 0.10 4.556 0.285
3 833.2 0.383 16.00 1.00
20 000 2.0 91.12 5.695

1Ounces per 1000 cubic feet or milligrammes per litre

Natural Vapour Pressure at 20 0 C:    

10°C (50°F) 9 150 mm Hg
25°C (77°F) 13 442 mm Hg

 

Mode of Action:

Sulfuryl fluoride is thought to inhibit the glycolysis and fatty acid cycles via the release of fluoride ions in the insects, thereby depriving them of energy necessary for survival.

Threshold Limit value (TLV):

5 ppm

Method of Evolution as a fumigant

From steel cylinders under natural pressure

Effects on different commodities

Effect on Metals, Paints, Enamels, Plastics, etc.:

No effects on Metals, paper, leather, rubbers, plastics, clothes, wall papers and other household articles.

Effect on Plants:

Germination of Seeds: Does not affect germination.

Effects on Plant Products:

Forms residual fluorides in food stuff in low quantities, but in certain items such as cheese, meat etc., high quantity of fluoride is formed.

Toxicity:

Although highly toxic to humans acutely exposed, there have been few reports of accidental poisoning. This may be due to the fact that sulphuryl fluoride aerates very rapidly from fumigated buildings and also because, in its present usage, it is only applied by properly qualified operators. Its mammalian toxicity by inhalation, is about equal to that of methyl bromide.

Sulphuryl fluoride is generally very toxic to all postembryonic stages of insects (Kenaga, 1957b; Bond and Monro, 1961), but the eggs of many species are extremely resistant. It has been suggested that this resistance is largely due to the impenetrable nature of the eggshell layers to this chemical (Outram, 1967).

Residues

Conversion: Residual fluorides

Residues : Food Articles- Very low..

Poison Symptoms

Respiratory irritation, central nervous system depression and then excitement.

Precautions

Do not expose to the Gas for longer period. The safe periods are 7 hr. at 200 ppm; 1 hr at 400 ppm; 5 minutes at 2000 ppm. The threshold limit is 5 ppm for repeated 8 hr exposure for five days. Special canister meant for this fumigant alone should be used. Alternatively, a self breathing apparatus should be used.

First Aid:

“Send for a doctor in case of accident. If a person should be overcome from breathing this gas, immediately place patient in fresh air, face downward, with head slightly below level of lungs. Keep warm. If breathing stops, give artificial respiration.

Note to physician: First symptoms expected are those of nausea, respiratory irritation and central nervous system depression; excitation may follow. Treat symptomatically. There is no known antidote.”

Usage as Fumigant

Extremely toxic to all stages of insects except egg stage which is tolerant even at high concentration. It has since been used to control termites and wood boring insects in timber.

Dosage

Empty structures, wood: 32 g/m3   for 24 hr at 10 to 14°C

16 g/m3 for 24 hr at 20°C.

 

 

 

 

 

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