How Often Do I Need To Clean My Kitchen Canopy & Exhausts?

Key Takeaways

• Minimum Frequency – Australian Standard AS181 states that canopies and exhausts should be cleaned at least once every 12 months.
• Best Practice Frequency – This can be as high as 1 clean per month in extreme situations. It will depend on the fuel (solid / non-solid), the food cooked and the cooking frequency. Tables 1a and 1b below provide more information.
• Grease Thickness Test – This test will help determine how often a clean is required. It’s recommended that on average the grease build-up across the system should be less than 0.2mm, and should not exceed 2mm in any one spot.
• Canopy Grease Filters – Inspected monthly and cleaned as required (monthly).

Kitchen canopy & exhaust cleaning – minimum frequency

Australian Standard 1851 states that a commercial kitchen canopy and exhaust system should be inspected monthly for ‘excessive grease accumulation’. Although not explicitly stated, the inference is that the system should be cleaned if there is ‘excessive grease accumulation’.

AS 1851 does explicitly state that the canopy and exhaust system should be cleaned at least every 12 months.

Note that AS 1851 does refer directly to Grease Filters as follows:

Filter (clean) – CLEAN grease-arresting filters as required (monthly). Owing to a wide variation in usage …. Cleaning may need to be more frequent than monthly.

Australian Standard 1851

Insurance policies often state the minimum required cleaning intervals for kitchen exhaust systems. It’s important to be aware that certain insurance agreements might mandate more frequent cleaning than what this guide suggests. Non-compliance with these stricter cleaning schedules could lead to the invalidation of the property insurance policy. This is especially problematic for fire insurance with fire damage costs often exceeding millions of dollars.

Kitchen Canopy & Exhaust Cleaning – Best Practice

The canopy and exhaust system should be cleaned when the grease build-up exceeds 0.2 mm on average across the system or if the grease build-up exceeds 2 mm in any one spot.  

Your professional commercial kitchen canopy cleaning company should assess this whenever they clean the system and advise you if the system should be cleaned either more or less frequently.

Grease build-up will depend upon a number of factors including:

1. The use of non-solid fuel systems (gas and electrical cooking) and the second table can be used for solid fuel systems (wood and coal cooking).
2. Cooking frequency.
3. The type of food you’re cooking and the level of grease-laden aerosols produced when they are cooked.

The following tables can be used to guide you on the cleaning frequency: 

Predicted Grease Aerosols	Cleaning Intervals (months)
	< 8 hours cooking / day	Between 8 and 14 hours cooking / day	> 14 hours cooking / day
Low	12	6	6
Medium	12	6	3
High	6	3	2

Table 1a – Non-solid fuel systems (gas and electricity) 

Predicted Grease Aerosols	Cleaning Intervals (months)
	< 8 hours cooking/day	Between 8 and 14 hours cooking / day	> 14 hours cooking / day
Low	6	3	1
Medium	3	2	1
High	3	2	1

Table 1b – Solid fuel systems (wood and coal cooking) 

Why Clean a Commercial Kitchen?

The primary reason to clean your Commercial Kitchen Canopy and Exhaust is to prevent a kitchen fire. However, fire is just one reason to clean your system. Here are 5 more reasons:

1. Compliance – If you are found not to be compliant with AS 1852 you will be fined
2. Unpleasant odours – A grease-ridden exhaust and duct system can result in mould and bacteria growth. Mould and bacteria growth can produce an unpleasant odour.
3. Pests – Grease and mould can be a source for pests including rats and mice.
4. Health Hazard – Grease, bacteria, and mould around food preparation is a health hazard and can cause sickness.
5. Increased Equipment Efficiency – Removing grease from the canopy, fans and ducts ensures the longevity of the kitchen equipment and reduces the likelihood of sudden breakdowns. It helps to keep the kitchen running smoothly and efficiently.

Kitchen Canopy & Exhaust Grease Thickness Test

To assess the necessity for cleaning, Grease Thickness Test measurements should be conducted. These measurements ought to be recorded at the following locations:

1. Hood(s) extract plenum(s) behind grease filters separators.
2. Duct 1m and 3m from each hood.
3. Duct midway between hood(s) and fan.
4. Duct upstream of fan and the fan itself.
5. Discharge duct downstream of fan.
6. Other location(s) noted with significant grease accumulations (e.g., at duct elbows and bends).

The Grease Thickness Test can be performed using four different methods, each suited to specific circumstances. These methods include:

1. Visual assessment
2. Wet Film Thickness test
3. Depth probe test
4. Electro-magnetic induction gauge.

The Visual assessment method is applicable for the Grease Thickness Test in cases of extreme fouling, where deposits exceed 3mm on the duct surface. This level is significantly higher than the acceptable 0.2mm, being over 15 times the limit. 

The Visual assessment can also be used when the duct is visibly free of grease deposits. This assessment involves inspecting the kitchen exhaust system’s components to determine whether they are visibly clean or dirty. A component is deemed visibly clean if its base surface is clearly visible without any grease or substances. If a component passes this visual check, no further Grease Thickness Test measurements are necessary.