For environmental and public relations reasons, flares should generally be designed to operate in a smokeless regime. However, as smokeless operation at the highest potential flow rates can be difficult to achieve, a design maximum flow rate for which smokeless operation is required is usually specified. Smokeless operation is typically accomplished by steam injection at the flare tip. However, other approaches to achieving smokeless flaring exist, such as air injection, and the use of high (≥~5 psig) flare discharge pressures. In some cases, these methods may be more practical and economical than steam injection.