Fog over

17 February 2017

Security fogging systems are widely used to help prevent robbery but how can users ensure they are fully effective? Lee Wallace explains an industry code of practice that will help.

THERE CAN be no doubt that security fogging is a very effective weapon in the arsenal of crime reduction ‒ but only if the systems have been specified, designed, installed and serviced correctly.

While the majority of installations fulfil these requirements, a small number of cases in which these systems failed to operate as intended was starting to affect consumer and insurer confidence in them. These systems failed not because of the fog generators themselves but often as a result of an error in the commissioning, installation, or servicing of the systems. For example, the fog generator was sited in the wrong location, system performance was poor because a generator did not have sufficient speed, density, or capacity to fill the protected area, or insufficient servicing or maintenance meant fog ejection was not, or only partially activated.

Understandably, the security fogging sector was keen to see if there was a way to reduce the number of such failures, which were beyond their control. As an advocate of the systems, I arranged for a number of security-fogging machine suppliers and manufacturers to get together and, with the help of the Metropolitan Police, National Police Chiefs Council (NPCC), National Security Inspectorate (NSI) and others, we were able to develop what has become the Association of Insurance Surveyors’ (AIS) Code of Practice.

The Code of Practice is intended to supplement the provisions of BS EN 50131-1, CLC/TS 50131-7 and EN 50131-8 as they apply to installations of Security Fogging Systems for use in ‘Hold-up – Building Occupied’ (EN50131-8: Appendix C, C.6). To this end, it addresses those main areas of concern: commissioning, installation and maintenance. 


Commissioning the correct fog generator for the required performance is key. Not all fog generators perform equally in terms of the speed, volume and density of fog generation. Therefore, selecting the correct machine performance for the required protection is the first part of the commissioning process. While this cannot be an exact science, because environmental factors differ in every location, the following extract from the Code of Practice was agreed: “Anti-raid Performance: Obscuration in the Protected Area to one metre or less within 10 seconds of the activation of the intruder and hold-up alarm system (IHAS) and not from when fog ejection starts”.

Speed and density of fog generation are critical aspects of a unit’s performance, especially in anti-raid situations. It is no good specifying a generator that is going to take 10 minutes to fill the protected area, or that fills quickly but not densely enough to obscure the target goods. The Code of Practice only specifies a speed and density in anti-raid performance for occupied premises. However, it is strongly recommended that it also be followed in unoccupied premises as, in a burglary situation, the quicker intruders are driven off the premises, the less time they have to take the targeted goods, so the lower the possible loss to the property owner and/or insurers. 

The location of the generator also plays a critical role in performance, as pointing it in the wrong direction, or at obstacles will delay the deployment of the fog.  

These factors led the fog-generator manufacturers and suppliers to agree that for each proposed installation, the machine and its location, as well as the risk assessment, should be submitted to them to sign off as being suitable and sufficient to achieve the desired protection. The Code of Practice states: “Prior to installation the risk assessment will be submitted to the equipment manufacturer, or the manufacturer’s authorised representative. If the risk assessment and equipment specification is appropriate the manufacturer will sign it and return it to the owner/installer.”

System installation

The equipment must be installed by competent engineers who have been trained in the installation of the generator specified. The Code of Practice states: “Installation and commissioning must be carried out by a technician who has been trained by the manufacturer in accordance with EN 50131-8 Annex C, C.8 and is in possession of a current training certificate. Installation must be in strict accordance with the risk assessment and recommendations.” 

The intended use of the fog generator and how it is to be connected to the IHAS should be confirmed. Is the system intended for ‘hold-up – building occupied’ only, or will it also be used for ‘building unoccupied’ (burglary), i.e. dual use? How will the system be activated? ‘Hold-up – building occupied’ activation should include the use of body-worn personal attack fobs. In the case of ‘Building unoccupied’ the system will be connected to an IHAS. 

The use of body worn personal attack fobs is important if property and/or people are to be protected in an anti-raid situation. If just fixed attack buttons are used, the person(s) present may not be able to reach them and activate the fog. In an armed robbery, personal protection would therefore be compromised; without being too dramatic, the ability to activate the fog can save lives and certainly reduce the time available to inflict injury and/or grab the target goods, or money.

As part of the installation process, end users should be trained not only in the correct use of the system but also in fault recognition.

Regular maintenance

Like most other security products, security fogging is not an install-and-forget measure. It is therefore essential that the whole system, including the fog generator, is maintained and serviced correctly by trained technicians.  

Some of the failures in operation of fog generators have been due to neglecting the generator, or failure to carry out some aspect of a service correctly, causing only partial fog ejection, or no fog ejection at all.

It was agreed that the security fogging device/system shall be covered by a maintenance contract and inspected on an annual basis, and that servicing and maintenance shall be carried out according to EN 50131-8: Annex C, C.9. Any changes to the ‘protected area’ should be noted and the risk assessment amended. The latter should then be resubmitted to the manufacturer for comment and confirmation. 

A written record of service and maintenance should be completed, and a service record sheet was created and added to the Code of Practice as Appendix A. This appendix was designed in such a way that the service technician can work through it, check off the relevant service aspects as completed and sign along with the end user to confirm that the service has taken place, and that any remedial work required has been carried out. Following activation, it is imperative that fluid levels are replenished; otherwise, the fog generator will be unable to perform a full activation capable of meeting the required performance.

The AIS Code of Practice is not a mandatory standard but following it is highly recommended. The existing European Standard is currently under review and it is hoped that the elements of the Code of Practice not currently in the standard will be incorporated. In the meantime, the Code of Practice will hopefully reduce the possibility of security fogging systems not performing as intended when called upon to protect people and property.

I would like to thank all of those involved for their time, patience and professionalism in helping develop the Code of Practice, which should help installers, specifiers and, most importantly, consumers understand what is required for an effective security fogging system.

Lee Wallace is chair of the Association of Insurance Surveyors. For more information on AIS or how to become a member, visit