Emergency controls

Phenylcarbamates. Phenylcarbamate herbicides represent one of two subgroups of carbamate herbicides, the phenylcarbamates and the thiocarbamates (299). Both groups are prone to volatilization losses the thiocarbamates are particularly susceptible and should be sod-incorporated immediately after apphcation (2). The carbamate herbicides are used, in general, for the selective pre-emergence control of grass and broadleaved weeds (299). Exceptions would include barban, desmedipham, and phenmedipham which are appHed post-emergence. 

Triazines. Triazine herbicides are one of several herbicide groups that are heterocycHc nitrogen derivatives. Triazine herbicides include the chloro-, methylthio-, and methoxytriazines. They are used for the selective pre-emergence control and early post-emergence control of seedling grass and broadleaved weeds in cropland (299). In addition, some of the triazines, particularly atrazine, prometon [1610-18-0] and simazine [122-34-9] are used for the nonselective control of vegetation in noncropland (2). Simazine may be used for selective control of aquatic weeds (2). 

Metal Organics and Inorganics. The metal organic herbicides are arsenicals used for the selective, post-emergence control of grass and broadleaved weeds in cropland and noncroplands. These herbicides are particularly usehil for weed control in cotton and turf crops (2,296,294). CacodyUc acid is a contact herbicide used for nonselective weed control in cropland and noncropland (299). Ammonium sulfamate [7773-06-0] (AMS) is an inorganic herbicide used for control of woody plants and herbaceous perennials (2). 

Miscellaneous Trifluoromethyl Compounds. The herbicides in this group are used for a wide variety of weed-control purposes. Acifluorfen, lactofen [77501-63-4] and oxyfluorfen are used for selective, pre-, and post-emergence weed control in croplands. Fluorochloridone is used for selective, pre-emergence weed control in cropland, and fluridone, fomesafen, and mefluidide [53780-34-0] are used for post-emergence control (296). Fluridone is also used as an aquatic herbicide (2). 

Cinmethylin and cloma2one [81777-89-1] are used for selective pre-emergence control and etholumesate [26225-79-6] for selective pre- and post-emergence weed control (2,296). 

Provision of an adequately equipped emergency control centre of suitable design located outside potential danger zones. 

An Emergency Action Plan should be established, assigning an emergency control center and appropriate personnel for emergency response. Drills should be carried out to assure all personnel are familiar with these plans. 

Maximum pressure developed (preliminary solution) when an emergency control valve suddenly closes ... 

Gas can feed a fire caused by other sources. The integrity of pipework should withstand an external fire for sufficient time for an external emergency control valve to be operated. 

Chloroacetanilides are soil-applied herbicides used for pre- and early post-emergence control of annual grasses and broadleaf weeds in crops. Representative chloroacetanilide compounds, alachlor, acetochlor, and metolachlor, are extensively used worldwide. Other chloroacetanilides with limited usages include propachlor, bu-tachlor, metazachlor, pretilachlor, and thenylchlor. Public environmental concerns and government regulatory requirements continue to prompt the need for reliable methods to determine residues of these herbicides. There now exist a variety of analytical methods to determine residues of these compounds in crops, animal products, soil, and water. The chemical structures and major crops in which these compounds are used are summarized in Table 1. 

C 2.41 X 10 mm Hg at 22.0°C 1.8mgL in water at 25°C Soluble in polar organic solvents Unstable in acidic, neutral and basic aqueous solutions Flumioxazin provides pre-emergence control of susceptible weeds in crops. Flumioxazin may also be used as part of an early preplant burn-down program in various crops... 

Fluthiacet-methyl is a selective contact herbicide for the post-emergence control of broad-leaved weeds in corn and soybeans. 

Overall effectiveness of protective systems and emergency controls. Protective systems, such as alarms, shutdown systems, and emergency controls, are often the keys to incident prevention and timely operator response. Protective systems that are properly designed, tested, and well maintained can reduce the frequency of event occurrence. Conversely, systems that are not tested and maintained may result in a high frequency of event occurrence. 

They should be located in the path of normal and emergency evacuation routes from the immediate area. In an panic situation personnel may immediately evacuate and not activate emergency controls if they are located at inconvenient locations. 

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