1 / 5

Product

Linear Heat Detection (LHD) Sensor CablesEN 54-22 Resettable5/3 mm Seamless Cu TubeSEC 15 Bare / SEC 20 Sheathed

Securiton SEC 15 / SEC 20 Copper-Tube Sensing Element Linear HeatEN 54-22 pneumatic seamless copper-tube sensing element for resettable linear heat detecti

SEC 15 and SEC 20 are EN 54-22 resettable pneumatic linear heat detection sensing tubes consisting of a precision-drawn seamless copper capillary tube (5.0 mm OD × 3.0 mm ID, bare Cu on SEC 15 or halogen-free polyethylene/PA over-sheathed on SEC 20). Any rapid

EN 54-22 Resettable
EN 54-22 Class A1I–CI
SEC 20 PE/LSZH Jacket
Order designation
SEC 20-RD Red Sheathed (50 m Coil)
Outer Ø ≈
6.2 mm
Copper weight
112 kg/km
Total weight ≈
128 kg/km
Min. bend R
62 mm
All sizes (12)
Request a quoteDatasheetWhatsApp
Engineering reply in 2 business hoursCut-to-length export drumsEN 10204 3.1 certificate per drum
Standard
EN 54-22
Resettable line-type heat detector
Tube geometry
5.0 / 3.0 mm
5 mm OD × 3 mm ID (1.0 mm Cu wall)
Sensing principle
Pneumatic Δp/Δt
Rate-of-rise & max temp diaphragm
Tube variants
SEC 15 / SEC 20
Bare Cu (SEC 15) · Sheathed (SEC 20)
Ambient range
-40 to +200 °C
Bare Cu +200 °C · Sheathed +80 °C
Min. bend radius
50 mm
Formed capillary tube bends

Typical values for this cable type, based on EN 54-22 / VdS — confirmed in the datasheet and quotation for your order.

Application fit

Is Securiton SEC 15 / SEC 20 right for your machine?

Specified for road and rail tunnels, underground car parks, aircraft hangars, historical timber roofs, paint spray booths and ATEX Zone 1/2 chemical plants where 100 % passive, EMI-immune, resettable thermal fire detection is required.

TBM gantry & advancing tunnel reel

Suitable

Industry-standard EN 54-22 ceiling-mounted pneumatic sensing tube for road, rail and metro tunnels.

Fixed installation

Suitable

Clipped to ceilings, tank roofs and cable galleries up to 120–150 m per sensing loop.

Furnace, kiln & high-temp zone

Suitable

Bare copper SEC 15 sensing tube withstands continuous ambient temperatures up to +200 °C.

Motorised monospiral reel

Not suitable

Precision-drawn seamless copper capillary tubing is strictly for fixed structural mounting.

SS-LDS braided LHD
Typical machinesRoad, highway & rail tunnelsUnderground & multi-storey car parksATEX petrochemical & paint boothsAircraft hangars & turbine hallsCold stores & food washdown zones

Construction

Layer by layer

Calibrated air-filled internal bore (3.0 mm ID) + precision seamless drawn phosphorus-deoxidized copper tube (5.0 mm OD, 1.0 mm wall, SEC 15) + extruded halogen-free PE/PA chemical-protection jacket (SEC 20).

123
Schematic, not to scale — generated from the layer data
#LayerMaterial & reference
1Seamless copper capillary tube (SEC 15)Precision-drawn annealed seamless phosphorus-deoxidized copper tube (Cu-DHP CW024A), 5.0 mm OD × 3.0 mm ID (1.0 mm wall)EN 12449
2Enclosed pneumatic air columnHermetically monitored dry air volume (3.0 mm bore) transmitting Gay-Lussac thermal pressure waves to the evaluation diaphragmEN 54-22
3Halogen-free protective sheath (SEC 20)Extruded 0.6 mm halogen-free polyethylene / polyamide corrosion-protection jacket (5.0 → 6.2 mm OD, Red, Black or Grey on SEC 20)EN 54-22

SEC 15 (Bare Copper Tube 5/3 mm)

Uninsulated 5.0 mm OD × 3.0 mm ID seamless copper sensing tube for fastest thermal response and ambients up to +200 °C.

SEC 20 (Halogen-Free Sheathed Cu Tube 6.2/3 mm)

5/3 mm seamless copper tube with a 0.6 mm halogen-free PE/LSZH outer sheath against road-tunnel de-icing salt, exhaust acids and ammonia.

Technical data

Ratings & operating limits

Typical values: Typical values for this cable type, based on EN 54-22 / VdS. Values for your order are confirmed in the datasheet and quotation.

Electrical

Electrical energy in sensing tube
0 V / 0 mA (100 % passive pneumatic tube; intrinsically safe in ATEX Zones 0, 1, 2, 20, 21, 22)
EMI & lightning immunity
100 % immune to electromagnetic fields, HV catenary induction and radiation

Thermal

EN 54-22 response classes
Class A1I, A2I, BI, CI (programmable via evaluation unit)
Operating temperature (SEC 15 bare Cu)
-40 °C to +200 °C continuous
Operating temperature (SEC 20 sheathed)
-40 °C to +80 °C continuous

Mechanical

Copper tube dimensions
5.0 mm OD × 3.0 mm ID × 1.0 mm wall (SEC 15) · 6.2 mm OD with sheath (SEC 20)
Minimum bending radius
50 mm (hand-formed or bending-roller radius)
Max. sensing tube loop length
Up to 120–150 m per pneumatic evaluation chamber

Resistance

Corrosion & chemical resistance
SEC 20 halogen-free sheath resists tunnel exhaust condensates, road salt, acids and alkalis
Resettable fire survival
Automatically resets after thermal transients below copper annealing/melting threshold

Reference standards

European product standard
EN 54-22 (Resettable line-type heat detectors) & VdS approval
Copper tube metallurgy
EN 12449 Cu-DHP (CW024A) seamless drawn tube

Identification

Tube finish & colours
SEC 15: Bright bare copper · SEC 20: Red (RAL 3000), Black (UV) or Grey
Coil marking
Stamped lot number, 5/3 mm tube dimensions and EN 54-22 system tag

Sizes

12 standard configurations (Securiton SEC 15 / SEC 20)

Nominal dimensions, masses and electrical ratings for Securiton SEC 15 / SEC 20 according to EN 54-22 / VdS.

Dimensions & masses
DesignationType & Coil LengthOD / ID mmOuter Ø ≈
mm		Copper
kg/km		Total weight ≈
kg/km		Min. bend R
fixed mm		Enquiry
Securiton SEC 15 / SEC 20 standard series
SEC 15 Bare Cu Tube (50 m Coil)SEC 15 Bare Cu · 50 m5.0 / 3.0 mm5.011211250
SEC 15 Bare Cu Tube (100 m Coil)SEC 15 Bare Cu · 100 m5.0 / 3.0 mm5.011211250
SEC 20-RD Red Sheathed (50 m Coil)SEC 20 Red PE/HF · 50 m6.2 / 3.0 mm6.211212862
SEC 20-RD Red Sheathed (100 m Coil)SEC 20 Red PE/HF · 100 m6.2 / 3.0 mm6.211212862
SEC 20-BK Black UV Sheathed (50 m)SEC 20 Black UV · 50 m6.2 / 3.0 mm6.211212862
SEC 20-BK Black UV Sheathed (100 m)SEC 20 Black UV · 100 m6.2 / 3.0 mm6.211212862
SEC 20-GY Grey Sheathed (50 m Coil)SEC 20 Grey HF · 50 m6.2 / 3.0 mm6.211212862
SEC 20-GY Grey Sheathed (100 m Coil)SEC 20 Grey HF · 100 m6.2 / 3.0 mm6.211212862
SEC 15-SS Stainless Tube 5/3 (50 m)AISI 316Ti Tube · 50 m5.0 / 3.0 mm5.0010050
SEC 15-SS Stainless Tube 5/3 (100 m)AISI 316Ti Tube · 100 m5.0 / 3.0 mm5.0010050
SEC 20-SS Sheathed Stainless (50 m)Sheathed AISI 316Ti · 50 m6.2 / 3.0 mm6.2011662
SEC 20-SS Sheathed Stainless (100 m)Sheathed AISI 316Ti · 100 m6.2 / 3.0 mm6.2011662
  • Typical values for this cable type; dimensions and weights for your order are confirmed in the quotation.
  • Nominal outer diameters and weights are subject to manufacturing tolerances per EN 54-22 / VdS.

Quality & approvals

Testing & inspection

Routine tests on every production length, sample and type tests per batch — documented on an EN 10204 3.1 inspection certificate.

  1. ConductorClass 5 stranding
  2. Spark test100 % in-line
  3. Lay-upCores, earth, fillers
  4. SheathingInner, braid / screen, outer
  5. Electrical testsAC voltage, resistance
  6. DimensionsOD, wall thickness
  7. Inspection documents & dispatchDrum & dispatch
Testing & inspectionTest value / referenceFrequency
Routine tests
Pneumatic pressure decay & hermetical leak test100 % pressure-hold verification at 5 bar with zero micro-leaks100 % of coils
Internal bore calibration & plugged-end checkVerified 3.0 mm ± 0.05 mm internal diameter and dry nitrogen purge100 % of coils
Sample tests
EN 54-22 Class A1I / A2I / BI / CI wind-tunnel response testCertified rate-of-rise and maximum temperature alarm responseVdS / EN 54-22 qualification

Inspection certificate

Issued with every drum, listing the routine test results for that length.

Product approvals

EN 54-22 Class A1I / A2I / BI / CIVdS System CompatibilityEN 12449 Seamless Cu-DHPATEX Passive Non-Electrical Sensor

Company certificates

ISO 9001ISO 14001ISO 45001VDE marks approvalUL / cULCE · LVD / EMC

Marking & supply

Ordering & delivery

Sheath marking

SEC 20 5x1mm Cu-DHP + 0.6mm HF SHEATH EN 54-22 LINEAR HEAT SENSING TUBE [lot/coil]
Delivery form
Fumigated export wooden drums or shrink-wrapped coils
Standard drum lengths
500 m · 1000 m standard drums (cut lengths on request)
MOQ
100 m (stock sizes) · 300–500 m (production)
Lead time
2–4 weeks ex-works
Incoterms
EXW, FOB, CIF, DAP

Technical documents

Downloads

PDFSecuriton SEC 15 / SEC 20 Copper-Tube Sensing Element Linear Heat – technical datasheet12 sizes · construction, technical data, approvalsXLSXSecuriton SEC 15 / SEC 20 spec data (Excel)All 12 sizes with dimensions and data, for your BOM or quotation
Revision
2026-10-20
Updated
2026-10-20

FAQ

Questions engineers ask first

Not covered here? Send your drawing — an engineer replies within 2 business hours.

How does the SEC 15 / SEC 20 copper-tube sensing element detect fire under EN 54-22?
The seamless 5/3 mm copper tube encloses a sealed column of air connected to a piezo-resistive pressure sensor and test stepper pump in the evaluation unit. When fire heats any section of the tube, the trapped air expands according to the Gay-Lussac gas law, generating a pressure wave that triggers both rate-of-rise (Δp/Δt) and maximum-temperature alarms.
When should sheathed SEC 20 be used instead of bare copper SEC 15?
Use bare copper SEC 15 in dry indoor areas, historic buildings, switchgear rooms or high-temperature zones up to +200 °C. Specify SEC 20 (with its 0.6 mm halogen-free polymer sheath) in road tunnels, car parks, food-processing plants and chemical facilities where de-icing salt, exhaust acids or ammonia would corrode bare copper.
How are multiple coils of SEC 15 or SEC 20 joined during installation?
Coils (50 m or 100 m) are joined using dedicated brass or stainless-steel twin-ferrule compression sleeves (ermeto couplings) or silver-brazed capillary sleeves. On SEC 20, the polymer outer sheath is stripped back 25 mm at the coupling and resealed with heat-shrink tubing after pressure testing.
Why is pneumatic copper-tube detection immune to ATEX ignition hazards and EMI?
Because the sensing element in the hazard zone is purely a hollow copper tube containing air at atmospheric pressure—with all electronics housed outside the zone—it carries zero voltage or current, making it completely immune to electromagnetic interference and safe in explosive atmospheres.

Request a quote

Get an engineering quote for Securiton SEC 15 / SEC 20

Your selection and application details are copied into the enquiry form below.

01Selected sizes

Use + Add next to a size or configuration.

02Reel & motion

Add your operating conditions here to include them in your enquiry.

03Message for our engineers

Securiton SEC 15 / SEC 20 Copper-Tube Sensing Element Linear Heat

Selected sizes:


Reel & motion:
- Reel type: 
- Drum core diameter (mm): 
- Cable length on drum (m): 
- Travel speed (m/min): 
- Max. acceleration: 
- Cycles per hour: 
- Length and quantity: 
- Ambient temperature: 
- Exposure (outdoor, water, oil, abrasion): 
- Destination country: 
- Equipment and operating conditions:
Send via WhatsApp

Digital LHD sensor

SS-LD Digital LHD

Fixed-temperature digital linear heat detection sensor cable

View productNylon-jacketed LHD

SS-LDN Nylon LHD

PA12 nylon-overjacketed chemical & UV resistant linear heat cable

View productSS-braided LHD

SS-LDS Armoured LHD

AISI 304 stainless-steel braided linear heat detection sensor cable

View productFire-resistant fibre optic

HITRONIC FIRE

FE180/E30–E90 circuit-integrity metal-armoured LSZH fibre optic cable

View product
DatasheetRequest a quote