If you are a manager or owner of an eating establishment and need to know what the frequency of your cleanings are… please see the chart below:

NFPA Code 96
Section 8-3.1 Hoods, grease removal devices, ducts and other appurtenance shall be cleaned to bare metal atfrequent intervals prior to surfacesbecoming heavily contaminated with grease or oily sludge. After the exhaust system is cleaned to bare metal, it shall not be coated with powder or other substance. The entire exhaust system shall be inspected by a properly trained, qualified and certified company or person (s) acceptable to the authority having jurisdictionin accordance with Table 8-3.1.