Frequenty Asked Questions


Q. Can Line type temperature detection systems REALLY provide superior detection response times to "other" types of detectors?

A. As a continuous detector in small diameter -3.5mms – cable format, line type temperature sensors can be located at the exact point of risk. Providing end users with an over-heat fire prevention capability and identify alarm point location.

Q. Which is the best linear temperature detection system?

A. Digital Linear Temperature Sensing provides a pre-specified alarm temperature with no minimum length exposure requirements together with simplicity of integration with all customer alarm control panels. Fibre optics linear offers many features such as 1.0m spatial resolution and accurate average temperature readings but is more suited for temperature monitoring than over-heat/fire detection.

Q. Can I integrate the Linear detection system with my central fire alarm control panel?

A.YES ….. by any number of options including solid state volt free contacts, RS232 serial link, programmable relays, Modbus etc. depending on system selected.

Q. What is the maximum length of sensor cable I can use on a zone?

A. This is dependent upon the Linear Detection System specified.  It can range from less than 100m to 200,000 metres.   As with all fire detection systems, good design practices should be maintained for system zoning.  As should alarm point location identification on longer zone lengths or where no visible flame exists (as with overheat risk conditions).

As currently there are no International standards exclusively related to linear temperature detection.  NFPA72 and EN54 standards are strictly followed – where appropriate.

Q. Should the linear heat sensor cable always be installed in direct contact with (or very close to) the equipment/risk it is protecting?

A. Unless it is the surface temperature of a specific piece of equipment that is considered to generate the major risk (i.e. motor bearing), there should always be a clear airflow around the heat sensor cable (except at regular sensor fixing/support points).  Surface contact – when not intended – can reduce response times because of the “heat sink” effect to that surface.

Q. Can point of alarm be identified?

A. YES....BOTH Proline DIGITAL and FIBRE OPTICS linear temperature sensing systems offer alarm point location.

Q. Can a single sensor cable have multiple alarm temperatures?

A. YES … Any number of different alarm temperature rated linear sensor cables can be series connected to compensate for differences in ambient temperatures within a single detection zone which might be caused by steam pipes, halogen lamps, heaters etc.

Q. Does a break in sensor cable always mean loss of detection?

A. NO … Use of the PROLINE optional ZI-07 interface unit provides loop wiring so a break in communications cable (to 2,000m maximum)  or sensor cable (to 3,000m loop per 1-10 local sensor units) would not mean loss of detection.

Q. Does the linear heat sensor cable need replacement after an alarm?

A. YES – As with all types of cables, sections which have been exposed to abnormal temperature conditions should be replaced with new sections to ensure there has been no alteration to cable characteristics.  It is most likely that other materials within the alarm area will also require replacement or repair.  Some linear detection equipment manufacturers promote their sensor cables as recoverable/resettable.  In practice this is not the case because all alarm conditions are localized events exposing averaging resistance/temperature cables – such as analog types – to temperatures above their failure levels.

Q. What is the ambient temperature range in which I can install linear heat sensor cables?

A. Minus 40C (-40F) to greater than 200C (+392F).  Depending on alarm temperature rated digital sensor cable or fibre optics linear temperature sensing system specified.

Q. Is there any recommended minimum temperature allowance between the specified maximum normal ambient and minimum alarm temperature?

A. International standards (UL521) recommend a minimum of 11C/20F between maximum specified ambient and the linear detection system alarm temperature.   Please remember that local hot spot temperatures should also be considered in alarm temperature selection – for example:

1.  Steam pipes
2.  Heaters or halogen lighting
3.  Reflected sunlight on a floating roof fuel storage tank.

Q. Is Linear Heat detection suitable for installation within designated hazardous areas?

A. All linear heat detection systems supplied by Proline Protection Systems Ltd are suitable for use on hazardous sites.  Any control or interface unit MUST be installed within a designated “safe” area, with the associated interconnecting cabling and heat sensor cable installed within the hazardous area.  System approved zener barriers will be supplied with the control or interface unit where required to provided ATEX certification.

Where required isolators may be used in preference to zener barriers but this MUST be specified to PROLINE in order a compatible isolator and correct interface unit is supplied.

Q. Are linear detection systems suitable for use within sub zero temperatures and/or corrosive environments?

A. YES.  Identification by the customer at the enquiry stage of such operating conditions will ensure correct product selection.  Proline linear temperature sensor cables have been tested and approved down to -40C (-40F) temperature levels.

Q. Why should I specify manufacturers approved fixings/clips for the sensor cable. They are sure to be more expensive than locally produced/supplied equivalents?

A. Manufacturers approved fixings should ALWAYS be specified because they have been designed to ensure correct sensor cable location- to maximize system sensitivity, and to promote continuous uninterrupted operation of the system.

Q. What is the recommended maximum spacing between clips and why?

A. 1m to 1.5m spacing provides good sensor cable support.  Where regular fixings are not possible, eye bolts and turn buckles with MESSENGER WIRE should be specified.

Q. What approvals do the Proline linear detection systems hold?

A. Depend on linear sensing equipment specified but include FM Approvals and UL Listing.

Q. How many levels of ALARM THRESHOLD can be set?

A. DIGITAL ….ONE(1)….A single set point alarm with no minimum exposed length requirement
FIBRE OPTICS…(3)… HIGH TEMPERATURE – maximum alarm set point exceeded
AVERAGE ……..General Ambient Rise/Rate of Rise

Q.What type of FAULTS will the Fibre Optics DTS controller monitor?

A. Self-diagnostics and will detect and signal supply loss plus interconnecting and sensor cable break.


Digital (LHS) & Analogue Linear Sensing

The means to locally monitor for temperature changes (rise or fall) at "point of risk" and at ANY /ALL locations along an installed length of temperature sensitive cable - regardless of environmental conditions.

Fibre Optic Linear Temperature Sensing

Line detection of temperature change and rate of rise along multi -kms lengths of small diameter fibre optic cable. It provides high performance near real time temperature Sensing and Alarm functionality with standard communication interfaces.

Proline 'Nero' Water & Moisture Detection

Rapid detection of the smallest of leaks within Industrial, Commercial Environments by a recoverable cable. Designed to provide 24 hours/day x 7 days/week continuous monitoring of areas where even the smallest of leaks can prove disastrous. Essential where undetected leakages can cause serious damage to today’s complex electrical, communications and computer networks.



A U.K. registered Company with hands-on product development, global market & application experience dating from the 1970's.

Proline equipment conforms to all NFPA 72 and EN54 standards requirements for linear detection.

Pneumatic, Digital, Analogue, Fibre Optics, Measuring Point System, Aspirating Systems...regardless of your linear detection requirement PROLINE will be happy to assist you.