Evolution EVC-DP

Technical summary

The Evolution Dual Photoelectric smoke detectors EV-DP and EVC-DP both use a new, unique Dual LED optical chamber, which utilises both Blue and Infra-Red LED’s to effectively measure the size of particles in the chamber.

This methodology is based on Gustav Mie’s particle scattering Theory (published 1908), and has enabled Nittan group to design cost effective Optical smoke detectors with a number of enhancements over standard Single Optic smoke detectors and Optical-Heat Multi-sensors.

Measurement of the particle size enables the smoke detector to discriminate between combustion particles and much larger particles (Steam, Dust etc) which are a major cause of False Alarms in Automatic Fire Detection systems.
In the event that Steam or Dust is present, the decision to Initiate a Fire Alarm condition can be inhibited or delayed.

Single sensor Optical smoke detectors (and even Multi-sensors) cannot make this decision, since they can only decide if the amount of scattered light striking the Photo-diode is greater than the Alarm threshold.

Single sensor Optical smoke detectors are basically sensitive to large and gray combustion particles generated by TF2 (Smoldering wood fire) and by TF3 (Smoldering cotton fire) and less sensitive to small combustion particles generated by TF1 (Open wood fire) and black particles by TF5 (Liquid (N-heptane) fire).

However, using the Dual Photo technique (and compensating algorithms), this lack of sensitivity can be reduced – again since the particle size is effectively being measured. In the presence of small or black combustion particles, the signal can be amplified (multiplied) to take it over the Alarm Threshold.
DP detectors can therefore replace Ionisation detectors, which ARE sensitive to small particles.

The DP detectors are still optical devices however, so they will remain insensitive to the invisible aerosols that Ionisation detectors respond quickly to (causing False Alarms).

Whilst DP detectors will give a reduction of False Alarm signals in the event of Transient Steam or Dust, which would set off Standard Optical detectors, they are generally not suited to being placed in Dirty or Dusty environments. Other detectors are available which can be safely situated in these environments.