These sprayers consist of one or two large tanks or canisters carried on the back or over the shoulder (depending on size and model). These usually have a capacity between 1 and 5 litres. The sprayer can disperse chemical irritants via short bursts or through a continuous spray until the tank is empty.
Whilst these sprayers can be used to or small groups, the employment of large capacity sprayers risks indiscriminately affecting everyone in the area, including bystanders. As there are no common standards on the concentration or amount of chemical irritant, safety of solvents, or the pressure of sprays, this may lead to inconsistency and more dangerous products being used. As most sprayers allow continuous spraying with no cut off, and this capability risks excessive amounts being used against a person. The volume of the chemical irritants dispersed can increase the risk of panic-driven stampedes, and cause serious injury or death through asphyxiation or agent toxicity, particularly if they are used in enclosed spaces or against restrained individuals.
