Jargon Buster

Letter A

ABC Dry Powder

ABC Dry Powder is a fire extinguisher agent which is suitable for use on class A, class B and class C fires. It is also suitable for electrical fires.

Addressable Fire Alarm Systems

The Main advantage of an Addressable Fire Alarm System is that unlike a Conventional or 2 Wire System, the Fire panel communicates directly with each device. So in the event of a fire, the fire panel will display the exact device (detector or call point) that signaled the alarm, allowing the fire to be located more quickly.

On a conventional system, there are often more than 10 detectors on a zone, so by examining the main panel, the user only knows that one of these ten detectors has signaled an alarm, meaning that further investigation is required to locate the fire.

Adjustable Back Check

Some door closers have a back check feature which prevents the door from being opened too quickly. Usually the door closer will have a valve located somewhere on the main body of the device which allows the amount of resistance to be adjusted.

Adjustable Latching Action

During the last 15° of closure a door closer has to cope with the increased resistance provided by the door latch. Door closers with an adjustable latching action will have a means of increasing/decreasing the closing force for the last 15° of closure to ensure that the door latches firmly and securely.

Automatic and Semi-Automatic Defibrillators


Designed for use by laypersons (ideally with basic training on how to use the AED but the units will give visual and audible instructions allowing practically anyone to use them successfully), these units will issue shocks as and when needed automatically.


Designed for use by healthcare professionals who are familiar with and can understand ECG (electrocardiogram) readings, these units will detect when a shock is required and alert the user who will then make the decision on whether or not the shock should be issued. Semi-automatic units also have a pacemaker function for occasions where the victims heart rate is too slow (bradycardia).

AFFF Foam - Aqueous Film Forming Foam

AFFF Foam is a water based fire extinguisher agent which is suitable for use on class A and class B fires.

Aico Ltd

Aico Ltd is a wholly owned subsidiary of Ei Electronics and is one of the UK's leading residential fire detection and CO detection specialist.

The Aico product range consists of:

  • Smoke and Heat Alarms
  • Fire Protection for Electrical Installations
  • Carbon Monoxide (CO) Alarms
Aico Logo

Alkaline Battery

Alkaline batteries use an alkaline electrolyte instead of the normal acidic ammonium chloride or zinc chloride electrolytes usually found in zinc-carbon batteries. They generally have a higher energy density and longer shelf life.

Amigo Fire Escape Ladder

ANSI - American National Standards Institute

ANSI facilitates the development of American National Standards (ANS) by accrediting the procedures of standards developing organizations (SDOs). The Institute oversees the creation, promulgation and use of thousands of norms and guidelines that directly impact businesses in nearly every sector.

ANSI is also actively engaged in accrediting programs that assess conformance to standards – including globally-recognized cross-sector programs such as the ISO 9000 (quality) and ISO 14000 (environmental) management systems.

Anti-arson Letterbox

Anti-tamper Seal

Anti-thrust Latch

An anti-thrust latch provides additional security for final exit doors. The latch cannot be retracted using unauthorised means or by applying force and will only retract using the correct method.

Anton Group

Automatic Gain Control

Over time dust will build up on the lenses of the system which will attenuate the beam. To compensate for this the system has Automatic Gain Control (AGC). This allows the beam to operate for longer without the need for cleaning by compensating for any change in the signal strength of the beam due to dust build up. Eventually the AGC will hit a limit, and will require cleaning – as with all optical beam smoke detectors. Over time buildings will settle slightly, or expand and contract as the seasons change. AGC is also used to compensate for this where the alignment of the beam is affected as a result. Again, this would cause a change in signal for which the beam will try and compensate for.

Automatic Synchronisation

The sounders with a sweep or tonal sound will all be in synchronisation.

Auxiliary Output

This is a relay with normally open and normally closed contacts which are triggered in a fire condition.

Alarm Grades by Power Type (BS 5839 Part 6)

Power Type Description BS 5839-6: 2013 Grade BS 5839-6: 2019 Grade
Battery Operated
9V alkaline battery operated smoke and heat alarms. Grade F Grade F2
Battery Operated
Sealed longlife lithium battery powered smoke and heat alarms Grade F (may be accepted as a replacement to grade D) Grade F1 and F2
Mains Powered
(Alkaline Back-up)
Mains powered smoke and heat alarms with 9v alkaline backup batteries Grade D, E and F Grade D2, F1 and F2
Mains Powered
(Lithium Back-up)
Mains powered smoke and heat alarms with sealed lithium backup batteries Grade D, E and F Grade D1, D2, F1 and F2