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Jargon Buster

Letter D

Dangerous Goods

Davy Descender

Day/Night Function

An engineer can program changes including detector sensitivity (high/low) and zone dependency settings.


Defibrillator Pads

When applying defibrillator pads, one pad is placed on the right side of the patients chest (just below the clavicle), and the other pad is placed on the left side of the patients chest (just below the pectoral muscle).

Non-polarized pads can be used in either of these locations, which makes applying them quicker and easier.

Delayed Closing Action

Fire doors in public buildings often need to be accesed by the elderly, less able people, wheelchair users and people with pushchairs.

The delayed closing action allows the fire door to remain open for a preset period of time whilst the user passes through the door. After the period of time has elapsed the door will close as normal.

Delay On Timer

The "delay on timer" is an adjustable timing function that will keep the emergency lighting illuminated until the conventional lighting has been fully restored.

DIN - German Institute for Standardisation

DIN, the German institute for standardisation, is a registered association, founded in 1917. With head office is in Berlin the organisation has been recognized by the German government since 1975 as the national standards body and represents German interests on International and European level.

DIN offers a forum in which representatives from the manufacturing industries, consumer organizations, commerce, the trades, service industries, science, technical inspectorates, government, in short anyone with an interest in standardisation, may meet in order to discuss and define their specific standardisation requirements and to record the results as German Standards.

Standardisation as undertaken by DIN is a service that aims to benefit the entire community.

DIN Standards promote rationalisation, quality assurance, safety, and environmental protection as well as improving communication between industry, technology, science, government and the public domain.

In DIN, standards work is carried out by some 26,000 external experts serving as voluntary delegates in more than 4,000 committees. Draft standards are published for public comment, and all comments are reviewed before final publication of the standard. Published standards are reviewed for continuing relevance at least every five years.

DIN 13157: Suitable for small companies (<20 workers or <50 office staff) and private households. Filings in accordance to DIN 13157 contain 72 items. Fillings can be stored for up to 20 years.

DIN 13169: Suitable for larger companies (>20 workers or >50 office staff). Filings in accordance to DIN 13169 contain 144 items. Fillings can be stored for up to 20 years.

Diode Base

The diode is a component fitted in the detector's base. If a detector is removed from its base, any detectors wired further along the zone will still be operational. They will not be cut off by the removal.

Discharge Range

Discharge Time

Distance Pieces

Door Closer


Double Door Strike

A double door strike is designed for use with a rim device on double door assemblies. The strike is fitted to the second opening leaf of the assembly while the rim device (e.g. panic/emergency latch) is fitted to the first opening leaf.


Double-knock facility

When a zone is activated this will trigger the panel. The double-knock facility halts the sounders until another detector is triggered on a different zone that it has been paired with.


Dry Powder

Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR)

The DSEAR 2002 is designed to help reduce the risks involving dangerous substances within the workplace. DSEAR puts duties on employers and the self-employed to protect people from risks to their safety from fires, explosions and similar events in the workplace, this includes members of the public who may be put at risk by work activity.