Heat Detectors – Rate-of-Rise and Fixed Temperature by Deyuan

Deyuan Marine offers heat detectors that combine rate-of-rise and fixed-temperature sensing in five grades: Grades 1, 2, 3 and Ranges 1, 2. Two matched thermistors -one exposed, one insulated – monitor temperature. A rapid rise creates a resistance difference that triggers a rate-of-rise alarm. A slow rise activates the fixed-temperature alarm via a series resistor. Fixed thresholds are: Grade 1 (60°C), Grade 2 (65°C), Grade 3 (75°C), Range 1 (80°C), Range 2 (100°C).

Electrical specifications: 17-28V DC, quiescent current 51 μA, alarm current 50-52 mA. Reset by 1-second power interruption. Operating range -20°C to +90°C, unaffected by pressure, IP54 rated. Compliant with EN54 and approved by LPCB/VdS. Colour-coded for easy identification. Deyuan delivers robust, dependable heat detection for demanding environments.

Heat Detectors -FAQ

1. What is the difference between a marine heat detector and a marine smoke detector?

A smoke detector senses airborne smoke particles and provides earlier warning of fire, making it the preferred choice for most areas. However, it is prone to false alarms in environments with steam, dust, or exhaust fumes. A heat detector senses temperature changes instead of smoke. It triggers an alarm when a fixed temperature is reached or when temperature rises too quickly. Heat detectors are more reliable in challenging environments like galleys, engine rooms, and workshops, but they respond more slowly than smoke detectors.

2. What are the two main types of marine heat detectors?

There are two primary types:

*Fixed Temperature (Static) Heat Detectors: These activate when the ambient temperature reaches a predetermined threshold, such as 58°C, 68°C, or 93°C. They are suitable for areas where rapid temperature changes are normal, like engine rooms and boiler rooms.

*Rate-of-Rise (RoR) Heat Detectors: These monitor the speed of temperature increase. They trigger an alarm if the temperature rises abnormally fast (e.g., ≥8°C per minute), providing earlier warning than fixed-temperature units. Most marine heat detectors combine both functions in one device.

3. Where should heat detectors be installed on a ship?

Heat detectors are essential in environments where smoke detectors would cause frequent false alarms. Typical marine applications include:

*Galleys and kitchens (due to steam and cooking fumes).

*Laundry rooms (due to steam and humidity).

*Workshops and dusty areas.

*Engine rooms and machinery spaces (due to exhaust fumes and oil mist).

*Boiler rooms.

4. What approvals should a marine heat detector have?

Marine heat detectors must be approved by major classification societies to ensure they meet the rigorous requirements of the maritime environment. Look for approvals from:

*DNV (Det Norske Veritas).

*Lloyd's Register (LR).

*CCS (China Classification Society).

*BV (Bureau Veritas).

*MED (Marine Equipment Directive) for vessels operating in European waters.

*For hazardous areas, ATEX and IECEx certifications are also required.

5. How often should marine heat detectors be tested and maintained?

Regular testing and maintenance are critical for ensuring reliable operation. Best practices include:

*Monthly testing: Test each detector using the built-in test feature (e.g., FasTest® on some models takes just four seconds) to confirm proper function.

*Regular inspections: Check for physical damage, dust accumulation, or obstruction of the sensing element.

*Immediate replacement: Replace any detector that fails testing or shows signs of damage.

*Training: Ensure crew members are properly trained in testing procedures, as Port State Control Officers (PSCOs) often request live testing during inspections to verify system functionality and crew competency.

6. What should I do when a marine heat detector alarms?

When a heat detector activates, follow these key actions:

*Sound the general alarm to alert all crew members.

*Notify the bridge team immediately.

*Assemble the fire party and prepare firefighting equipment.

*Isolate the area by closing ventilation, doors, and skylights, and apply boundary cooling if necessary.

*Don appropriate PPE and use the correct fire extinguishing system based on the fire type.

*Do not ignore the alarm – "alarm fatigue" can be dangerous. Treat every alarm as a real emergency until confirmed otherwise.

7. Are marine heat detectors stand-alone units?

Generally, no. Most marine heat detectors are not stand-alone units. They are designed to connect to a fire alarm control panel (FACP) on the bridge or in the fire control station. The detector itself typically does not have a built-in audible alarm – the panel provides visual and audible alerts. Some detectors, however, include a visual indicator (LED) to show alarm status or fault conditions.