The reefers are using some heat exchangers that behaves as water cooled condensers&colon; water cooling. In the U.S., ASME publishes several performance test codes on condensers and heat exchangers. Evaporators and suitably configured direct-contact condensers were developed and patented by SERI (see ). These plants contain surface condensers, heaters, and coolers, all of which contain copper tubing. Moreover, the heat from the condensers of the chillers is recovered. Radiators used as condensers could also contain lead at the connections to the plumbing. Dimroth condensers are more effective than conventional coil condensers. Use of cooling water or surrounding air as the coolant is common in many condensers. The twin natural-draft cooling towers are tall and provide cooling to the plant's main condensers. In laboratory distillation, several types of condensers are commonly found. These include ASME PTC 12.2-2010, Steam Surface Condensers, and PTC 30.1-2007, Air cooled Steam Condensers. Phthalic anhydride and maleic anhydride are recovered by distillation by a series of switch condensers. Synchronous condensers are also useful for supporting voltage levels. Lenses with finer steps serve as condensers in overhead projectors. Grid strength can be increased by installing synchronous condensers.