Hochiki DRD-E Conventional Infrared Flame Detector Installation Manual

1 General

1.1 Description

The DRD-E flame detector is designed for environments where open flaming fires are anticipated. It detects the light emitted by flames during combustion. The detector differentiates between flames and other light sources by responding to specific optical wavelengths and flame flicker frequencies, thereby preventing false alarms from sources like flickering lights.

1.2 Alarm Response Modes

When a flame is detected, the detector typically latches into an alarm state. To reset the detector, the power supply must be removed.

1.3 IR Detection Basics

Flame detectors are categorized by their detection principle: UV detectors respond to ultraviolet light, while IR detectors respond to infrared light. The DRD-E detector specifically detects infrared radiation from flames. Flames from hydrocarbon combustion emit IR radiation with a peak emission at 4.3 micrometers (μm) and flicker frequencies between 2 and 15 Hertz (Hz).

Diagram: External View of DRD-E (Fig 1)

The detector has a circular form. The top view shows an alarm indicator (red) and a central window made of sapphire glass. The side view indicates dimensions: a diameter of 100mm and a height of 37.3mm (or 45.3mm).

Diagram: Spectrum of white gas flame (Fig 2)

This graph illustrates the correlation coefficient against wavelength in micrometers. It shows a significant peak at approximately 4.3 μm, identified as the resonance frequency of CO2, indicating strong IR emission from flames. Smaller peaks are present between 2.5 and 3.0 μm.

The detector utilizes a pyroelectric device with an optical filter to detect CO2 formation during combustion. The signal is amplified within the 2 to 15 Hz range. The DRD-E detector then processes this signal using an AC-DC converter and comparator, followed by a capacitor, to make a fire decision. An alarm signal is transmitted to the fire panel via a switching circuit.

2 Application

The DRD-E flame detectors are suitable for applications requiring detection that is:

• Unaffected by convection currents, draughts, or wind.
• Tolerant of fumes, vapours, dust, and mist.
• Fast reacting.

2.1 Detectable Fire Sources

• Liquids: Aviation Fuels (kerosene), Ethanol, Methylated Spirits, n-Heptane, Paraffin, Petrol (gasoline).
• Solids: Coal, Cotton, Grain & Feeds, Paper, Refuse Wood.
• Gases: Butane, Natural Gas, Off Gas, Propane.

2.2 Typical Applications

• Coal handling plants
• Aircraft hangars
• Atria
• Automotive industry (spray booths, parts manufacture)
• Paper manufacture
• Pharmaceutical facilities
• Engine rooms
• Generator rooms
• Metal fabrication workshops
• Waste handling facilities
• Woodworking shops
• Power plants
• Textile manufacturing
• Transformer stations
• Petrochemical facilities

2.3 Applications and Locations to Avoid

• Environments with ambient temperatures exceeding 50°C.
• Dusty or steamy atmospheres.
• Atmospheres containing corrosive gases.
• Areas where condensation is likely to form.
• Proximity to strong infrared (IR) sources such as heaters, burners, or flares.
• Close proximity to Radio Frequency (RF) sources.
• Locations with obstructions to the detector's field of view.
• Exposure to direct weather conditions.
• Areas with significant amounts of flickering reflections.
• Direct sunlight or its reflected light from surfaces like puddles, glass, or metal.
• Spot lighting directed onto the detector optics.

3 Quantities and Positioning

The number and placement of detectors depend on:

• The anticipated size of the flame.
• The distance between the flame and the detector.
• The angle of view required for the flame detector.

The DRD-E flame detector achieves Class 1 performance as defined by BS EN54-10 on its high sensitivity setting. This means it can detect an n-heptane (yellow) fire of 0.1m² or a methylated spirit (clear) fire of 0.25m² at a distance of up to 25 meters within 30 seconds.

The detector can reliably detect fires at distances up to 40 meters, provided the flame size is proportionally larger. For instance, a flame that is 0.1m² and detectable at 25m would need to be 0.4m² to be reliably detected at 40m.

Distance Calculation Formula

In a rectangular room, the maximum distance from the detector to the fire is calculated using the formula:

Maximum distance = √(L² + W² + H²)

Where L is Length, W is Width, and H is Height.

Diagram: Calculation of distance from detector to flame (Fig 3)

This diagram illustrates a 3D view of a room, showing a detector at one corner and a flame at the opposite corner. It labels the dimensions Length, Width, and Height and presents the distance calculation formula.

3.1 Field of View

The DRD-E flame detector has a field of view of approximately 90 degrees.

Diagram: Conical field of view of the flame detector (Fig 4)

This diagram depicts a cone emanating from the detector, representing its 90-degree field of view, with a central line indicating the detector's primary axis.

Diagram: Detector Field of View Plot (Fig 5)

This polar plot details the detector's detection capabilities. The center represents the detector. Radial lines indicate distances (up to 40m), and angular lines show the field of view (from -90° to +90°). Curves show that a 0.1m² flame can be detected at 25m, and a 0.4m² flame at 40m.

Positioning Recommendations:

• Position detectors at the perimeter of the area, pointing towards the anticipated flame source or the center of the area to be protected.
• If the detector cannot cover the entire area, additional detectors may be necessary.
• The detector is not affected by normal ambient light sources, but direct sunlight should be avoided on the viewing window.

3.2 Detector Window Contamination

It is crucial to maintain the cleanliness of the detector window. Regular checks, determined by local conditions and the degree of contamination, are recommended to ensure optimal performance. While IR detectors can still detect flames with a contaminated window, sensitivity may be reduced.

3.2.1 Cleaning

If the DRD-E flame detector's window is coated with dust or oil, its sensitivity to flames may decrease. To clean the window, use a damp cloth, ensuring to remove any excess moisture with a dry cloth. Note: Do not use alcohol or benzine to clean the detector window.

4 Installation

The DRD-E flame detector is compatible with the following mounting bases: YBN-R/6, YBO-R/6R, YBO-R/6RN, YBO-R/6PA, YBN-R/6SK, and YBN-R/6RS. Wall and ceiling mounting brackets are also available separately.

Diagram: Installation with Mounting Base (Fig 6)

This diagram shows the DRD-E detector being attached to a circular mounting base.

Diagram: Installation with ceiling bracket (YZU-A) (Fig 7)

This diagram illustrates the detector and its base being mounted using a ceiling bracket (YZU-A).

Diagram: Installation with wall bracket (YZU-B with YZU-A) (Fig 8)

This diagram shows the detector and its base mounted using a wall bracket (YZU-B, possibly in conjunction with YZU-A).

Diagram: Connection to Conventional Control Panel via CDX Mounting Bases (Fig 9)

This diagram provides wiring configurations for connecting the DRD-E detector to a conventional control panel using various mounting bases. It details connections for Zone positive (+ve), Zone negative (-ve), and Cable Screen. It also shows how to connect a Remote Indicator and explains the function of RC Relay Contacts (selecting Normally Closed (N/C) or Normally Open (N/O) configurations).

• Base Types and Functions:
  • YBN-R/6: Common Mounting Base.
  • YBN-R/6SK: Common Mounting Base c/w Schottky Diode.
  • YBO-R/6RN: Non-Latching Relay Base
  • YBO-R/6RS: Latching Relay Base c/w Schottky Diode.
  • YBO-R/6PA: For use with compatible 2-Wire systems.
  • YBO-R/6R: Latching Relay Base
• Note: Alarm control panel compatibility is required for certain base types.

4.1 Functional Testing

A portable flame detector test unit is available to simulate flame behavior. To test the detector, the unit must be positioned within 600mm of the DRD-E flame detector. The DRD-E incorporates a 15-second delay to filter out transient IR sources. After each test, allow the detector one minute to stabilize.

If conditions permit and it is safe to do so, a naked flame can also be used for testing. Exercise caution to prevent direct exposure of the flame to the detector's casing or lens, as this could cause damage.

Diagram: Portable Flame Detector Test Unit (Fig 10)

This diagram shows a handheld test unit with a keypad and display, positioned close (less than 600mm) to the DRD-E flame detector.

4.2 Service & Repairs

Servicing of the fire protection system should be performed by competent individuals familiar with the system type or as advised by local regulations. Repairs to the flame detectors must only be carried out by the manufacturer or an authorized representative, typically at the manufacturer's factory.

5 Detector Specifications

5.1 Compatible Bases

Note: Alarm control panel compatibility is required for certain base types.