Grease Extraction

Kitchen extract (exhaust) systems are particularly affected by the deposition of grease and oil on internal surfaces. No separator or filter device can be 100% effective and, consequently, varying efficiencies of separation or filtration affect the rate of fouling. Likewise, other industrial cooking processes can result in an accumulation of grease and oil that becomes hidden inside ventilation systems.

To comply with the Regulatory Reform (Fire Safety) Order 2005, or equivalent national legislation, grease extract systems must be inspected, tested and cleaned regularly to ensure the mitigation of fire hazards. In addition, advice and guidance provided by the Health & Safety Executive (HSE), BSRIA and RISCAuthority, stipulate that kitchen extract systems should be kept clean to minimise fire and health and safety risks.

Spontaneous ignition of residual grease or oil deposits occurs at 310-360oC.  Deposits of some mixtures, such as chicken fat or vegetable oil, ignite more readily. Therefore, under certain circumstances flames and/or high temperatures can ignite grease, causing fire to spread rapidly through a system in situations where grease levels have not been adequately controlled in accordance with TR 19® Grease. In addition to this, the ductwork can be heated to such a degree that ignition of the surrounding materials, in contact with or in close proximity to the duct, can occur. Fire Services and forensic fire investigators report many cases where, a small kitchen fire has been spread well beyond the original seat of fire by grease-laden extract systems, causing major property damage well beyond the confines of the kitchen leading to significant business interruption.

For this reason, insurers have increased their attention on the ‘fryers’ warranty’ as well as requiring specific cleaning frequencies and detailed proof of compliant cleaning maintenance regimes. Claims may be refused by insurers where compliance with the terms of the insurance policy cannot be demonstrated.

It is essential that a kitchen extract ductwork system, canopy and extract plenum, are fitted with access panels of sufficient number, quality and size to enable unrestricted access for regular cleaning and inspection of the internal surfaces and in-line components. All panels shall be in accordance with the requirements of DW144 and DW172.

Frequency of cleaning – control of grease and fire risk

All operational grease extract ductwork systems will usually require cleaning annually as a minimum.

The frequency of cleaning should be sufficient to ensure that grease deposit limits of 200µm, as a mean across the system, are not exceeded.

To assist in establishing the initial cleaning frequency for the system in the absence of data on the historical pre-clean grease thickness levels and duration of days between each set of grease thickness readings.

Initial Clean Frequency Calculator

A comprehensive Post Cleaning Report (PCR) is issued after completion of works to demonstrate the fire safety cleaning of the grease extract system, has been done so in a competent manner and in accordance with TR19 Grease.


  • An executive summary page
  • Other hazards that have been identified.
  • Micron readings for the test locations & the mean (average) micron reading across all micron readings taken.
  • The current cleaning frequency & recommendations of a new cleaning frequency based on the micron readings
  • A sufficient number of before and after cleaning photographs of the system to give a true representation of the system condition.
  • A schematic diagram of the system layout showing the system
  • Test locations identified on the schematic.

As full members BESA, inspection and cleaning works are carried out adhering strictly to the TR19 Grease Specification (Fire Risk Management of Grease Accumulation within Kitchen Extraction Systems)

We provide verifiably high-quality service and value for money through a combination of technology, experience and specialist skills. Kitchen Grease Extract cleaning is achieved effectively, safely and cleanly.

Please get in touch via our contact page or alternatively give us a call to discuss your requirement call: 0191 2366023

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