Q=C⋅A0.82cap Q equals cap C center dot cap A to the 0.82 power = Total heat absorption rate (BTU/hr or Watts).

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API Standard 521, titled is an essential technical document published by the American Petroleum Institute (API). It serves as a cornerstone standard for engineers involved in the design, operation, and maintenance of oil and gas facilities, petrochemical plants, and liquefied natural gas (LNG) terminals.