System Sensor BS5839

Note: This document is based on the recommendatio ns of BS5839 Part 1: 2002. I t is intended only as a guide to the ap plication of ﬁre detection systems.

Reference must be made to relevant national and local stan dards.

2251EM PHOTOELECTRIC SMOKE SEN SOR

The 2251EM photoelectric smoke detector c ombines a state

of the art sensing chamber with micropro cessor control

and sophisticated processing to elimina te transient noise

conditions thereby giving reliable ﬁre de tection whilst

minimising unwanted alarms. It is approved to a ra nge of

sensitivities, permitting the det ector to be conﬁgured to match

the application environment.

The 2251EM includes algorithms, which compens ate for

a slow build up of contamination such as dust , within

the sensing chamber. Once the detector has reach ed its

maximum compensation level, a signal can be sen t to the

control panel to indicate the need for main tenance.

Tested and approved to EN54-7: 2000 by LPCB

Speciﬁcations

Height: 45mm in B501 Base

Weight: 102g excluding base

2251TEM PHOTO–THERMAL SENSOR

The 2251TEM multi-criteria ﬁre senso r incorporates an optical

smoke-sensing chamber and thermal-sens ing elements

combined with microprocessor contr ol and sophisticated

processing to eliminate transient noise co nditions thereby

giving reliable ﬁre detection whilst minimis ing unwanted

alarms. It can respond either as a smoke det ector, or a rate of

rise heat detector or, using special algorithms c ombining both

elements to provide improved reliabilit y of detection.

The 2251TEM is an environmentally friendl y replacement

for an ionisation detector, providing rapid de tection of

fast, ﬂaming ﬁres without incurring t he signiﬁcant end-

of-life disposal costs associated w ith products containing

radioactive material.

The 2251TEM is approved to a number of sensitivi ty settings:

Three Photo-Thermal and two Auto-A djusting, which slowly

adjust the detector’s sensitivit y to match short term changes

in its environment, thus reducing the po tential for nuisance

alarms. In addition, it is possible to dete ct an alarm from heat

only, for day/night operation for example.

Similarly to the 2251EM, the 2251TEM includes algori thms,

which compensate for a slow build up of contamin ation,

such as dust, within its optical sens ing chamber. Once the

detector has reached its maximum co mpensation level, a

signal can be sent to the control panel to indi cate a the need

for maintenance.

Tested and approved to CEA 4021, EN54-7: 200 0 and EN54-5:

2000 (Class A1R) by LPCB

Speciﬁcations

Height: 45mm in B501 Base

Weight: 115g excluding base

System Sensor Intelligent Product Range