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HD1 Range


The MEDC heat detector has been designed for use in hazardous environments. These units are suitable for fire alarm and/or suppression systems in offshore and onshore applications including paint spray booths, flammable material stores, turbine rooms, extract ductwork and other hazardous areas throughout the oil & gas, petrochemical and process industries.

Comprising a Fenwal rate-compensated detector with all-stainless steel external construction, mounted to either a type SM87 marine grade alloy enclosure (Ex d version) or JB10 corrosion-free GRP enclosure (Ex ia, Ex em/UL versions). The contact in the detector CLOSES at alarm temperature.

To select appropriate temperature setting see specification on reverse.

Data Sheets
HD1 (695 KB) (PDF)
HD1 North American (358 KB) (PDF)
Product Certificates
ATEX Ex em II (304 KB) (PDF)
ATEX Ex ia IIC (1 MB) (PDF)
ATEX Ex d IIB (1 MB) (PDF)
ATEX Ex d IIC (2 MB) (PDF)
UL (OVER 599 DEG F) (250 KB) (PDF)
UL (UP TO 599 DEG F) (250 KB) (PDF)
CQST Ex ia (325 KB) (PDF)
TR CU EMC (435 KB) (PDF)
Ex e IP66 Certificate (28 KB) (PDF)
SIL 2 (2 MB) (PDF)
ABS Ex ia IIC (44 KB) (PDF)
Product Certificates – External Link
Schematics / Wiring
Ex d Schematic (122 KB) (PDF)
UL Schematic (50 KB) (PDF)
HD1 Wiring (65 KB) (PDF)
Ex ia Schematic (65 KB) (PDF)
Technical Manuals
Ex d IIC (TM228) (46 KB) (PDF)
UL (TM186) (44 KB) (PDF)
Certification ATEX, IECEx, UL, TR CU, Russian Fire Approval,CQST, ABS, SIL 2
Explosion Protection

Ex II 2GD Ex d IIB T6
Ex II 2 GD Exd IIC ExtD A21 T85ᵒC
Ex II 2 G Ex em II T6 (T4 with diodes/resistors)
Ex II 1 G Ex ia IIC T6 (T4 with diodes/resistors)

IECEx Ex ia IIC T4/6 Ga.

Area Classification Zone 0, Zone 1 and Zone 2 use.
Certified Ambient Temperature -20°C to +125°C Exd (T3) ATEX/TR CU
-20°C to +55°C Exd (T6)/Ex em/UL
-55°C to +55°C Ex ia
Ingress Protection IP66 & IP67
Material Enclosures: Marine Grade Alloy (Ex d)
                     Corrosion-free GRP (Ex ia/Ex em/UL)
Detector: Stainless Steel
Cover Screws: Stainless Steel
Temperature Settings 140°F to 725°F (60°C to 385°C)
Entries 2 x M20 ISO
Weight 1.1-2.0kg (model dependent)
Options Enclosures, guard, colour, tag and duty labels,
temperature setting. Series and EOL resistors,
blanking plugs.



  • Zone 0, Zone 1 and Zone 2 use.
  • UL listed for USA and Canada
    • Class I, Div 2, Groups A-D.
  • Ex ia IIC T4/T6, Ex d IIB T3/T6 or Ex em II T6.
  • ATEX approved:
    • – Ex II 1G (Exia)
    • – Ex II 2G (Exd/Exem).
  • IECEx Certified Ga
  • BASEEFA certified.
  • TR CU certified.
  • SIL 2 certified.
  • Chinese (CQST) certified.
  • IP66 & IP67.
  • Certified temperature:
    • –20°C to +125°C (Ex d)*.
    • –20°C to +55°C (Ex em/UL).
    • –55°C to +55°C (Ex ia).
  • Stainless steel probe.
  • Detector temperature settings:
    • 60°C to 385°C
    • 140°F to 725°F
  • Marine grade alloy or GRP enclosure*.
  • Optional guard.

*Model dependent.