Engine Room Heat Detectors - Fixed & Rate-of-Rise

Fireboy's Orbis Marine Heat Detector range includes heat detectors to suit a wide variety of operating conditions in which smoke detectors are typically not suitable – typically due to the occurrence of smoke, steam, or minor temperature fluctuations.

Heat detectors are classified into three groups by the highest ambient temperature in which they can safely be used without the risk of false alarms.
In addition, detectors in each temperature classification are available in either Rate-of-(temperature)-Rise or Static (Fixed) temperature models.
All heat detectors in the Orbis Marine range are tested as rate-of-rise or static detectors and are classified as A1R, A2S, BR, BS, CR and CS - where the last laetter refers to R-O-R or Static.

Operation Orbis Marine Heat Detectors have an open-web casing which enables air to flow freely across a thermistor which measures the air temperature every two seconds.
A microprocessor stores the temperatures and compares them with pre-set values to determine whether a fixed upper limit - the alarm level - has been reached.

Static Heat Detectors respond only when a fixed temperature has been reached.
Static detectors will not respond below their minimum response temperature even when exposed to high rates of rise of air temperature.
Static detectors can be suitable for areas such as engine rooms, kitchens and boiler rooms where large, rapid temperature changes are considered normal.

Rate-of-Rise Detectors incorporate a microprocessor which uses algorithms to determine how fast the temperature is increasing.
Rate-of-rise detectors also have a fixed upper limit, but they also measure the rate of increase in temperature. Thus, a fire might be detected at an earlier stage than with a static detector.
This means that a rate-of-rise detector is typically preferred to a static heat detector unless sharp increases of heat are part of the normal environment in the area protected by the heat detector.

Where to use heat detectors
Heat detectors are used in applications where smoke detectors are found to be unsuitable.
Typically, Smoke Detectors are used whenever possible — since smoke detection provides earlier warning of fire than heat detection.
Heat Detectors, on the other hand, should be used if there is a danger of nuisance alarms from smoke detectors due to normal production of smoke or steam.

NOTE — These detectors are not standalone units.
They need to be connected to either the Fireboy FBD-2 or FBD-MZ Fire Detection Panels. There is no audible alarm on these detectors (panel will audibly alarm) and no visual alarm.

Choosing the correct class of heat detector
Heat detectors have a wide range of response characteristics and the choice of the right type for a particular application may not always be straightforward.
Use the most sensitive heat detector available consistent with avoiding false alarms.
Fireboy Orbis Heat Detectors are available for ambient temperature limits of:
• 135°F - A1R and A2S models
• 163°F - BR and BS models (may be suitable for Engine Room applications)
• 194°F - CR and CS models (may be suitable for Engine Room applications)
As a point of reference, Fireboy Automatic Fire Suppression Systems, which are typically installed in engine rooms, deploy at 175°F.
It may be necessary to take an heuristic (trial and error) approach until the best solution for a particular location has been found.

Please see the linked Orbis Marine Heat Detector Datasheet for a helpful flowchart for selecting an appropriate heat detector model.

• Operation from 8V to 33V DC
• Sampling frequency: Once every 2 seconds
• Red flashing LED at StartUp confirms the device is operating.
• SensAlert®, yellow flashing LED indicates faulty operation
• FasTest® takes just four seconds to test and confirm detectors are functioning correctly
• Dimensions without Base: 3.82" Dia. x 1.42" High (97mm x 36mm)
• Dimensions with Base: 3.92" Dia. x 2.01" High (100mm x 51mm)
• Weight: 2.47 oz; Weight with base: 4.59 oz

For units without bases, use OMDB-01 Base. See Related Products.