Sequoia Sensors with Dry Contact Output

A family of low cost industrial sensors with dry contact output

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Key Features
  • Designed for industrial applications
  • Low cost and reliable
  • Tried and tested products
  • Power
  • Smoke
  • Gas
  • Flood
  • Door contact
Buy Online
Part Number Weight Pack Qty Code Price (Ex VAT) Stock
Door Contact Switch DOOR CONTACT
500g 1 30913 1+ £7.46 Yes (9)
500g 1 31680 1+ £24.86 Yes (9)

Detects and/or disconnects 110 to 230V AC mains voltage.

500g 1 31423 1+ £116.91 No
GS-133 Gas Detector GS-133 Gas Leak Detector
Flammable gas detector GS-133
500g 1 33488 1+ £84.10 Yes (4)
Smoke Detector FDR26
500g 1 31940 1+ £79.97 Yes (1)

Place your order before 2pm to select next day delivery. In a hurry? pre 10:30am delivery also available.


A family of sensors for use in industrial market with dry or Volt-free output. These sensors are specifically designed to work with any monitoring system that can interface to a dry contact sensor for monitoring purposes.

Low cost and reliable, these sensors can be used in any situation, including domestic, office, warehouse and server and computer rooms.

A dry or Volt-free contact is a contact without any voltage going through it. This effectively is a switch, meaning that if a sensor has a dry contact output, the switch will close when the sensor is triggered due to the presence of what it is measuring.

Dry contact sensors do not give a value. They detect the presence of something, whether it is gas, door close, smoke, water leak etc.

These types of sensors are normally connected to products that are monitoring events and act upon them, either by sending an alert or triggering a relay for example.

Although the output of the dry contact sensor is virtually volt-free, most require a DC voltage supply to operate. This power is either taken from the monitoring system, or by connecting the sensor to a wall socket.

Brief Description of Sensor Properties:

  • 133 Gas Detector: Detects all types of flammable gasses (natural gas, coalgas, propane, bottle-gas, acetylene, hydrogen, etc.). Will sound an internal buzzer and will also send a relay signal to the monitoring unit triggering an alarm.
  • Door Contact: Will send a dry contact signal to the monitoring unit when door/window opens/closes.
  • FDR26 Optical Smoke Detector: Will send a signal to the monitoring unit when smoke is detected.
  • Poweregg: Will detect presence or lack of 110V- 230V AC mains voltage and switch dry contact. Can also be used turn off power.

    Power Egg is designed to detect and/or disconnect 110 to 230V AC mains voltage. The controlling and controlled circuits are electrically isolated. Low-voltage, closing contacts are used for detection indication and output control.

    PowerEgg is a "pass-through mains outlet" with two IEC-320 connectors – a plug (C14) at the input, and a socket (C13) at the output.

    PowerEgg combines two functions in a single device:

    • DETECTOR: Detects the presence of mains voltage at the input (indication with a change-over contact)
    • CONTROL: Disconnects the output voltage (control with external DC voltage or a contact)
  • LD-12 Flood Detector: Will detect presence of water or conducting liquid spot and trigger a signal.

Gas detection sensitivity

Sensitivity (concentration):
Methane Propane Iso-butane
first level 10 ± 3% LEL (0.50% vol) 18 ± 3% LEL (0.30% vol) 23 ± 3 % LEL (0.30% vol)
second level 18 ± 3% LEL (0.80% vol) 30 ± 3% LEL (0.50% vol) 40 ± 3 % LEL (0.50% vol)
LEL = Lower explosive limit (100%) according to IEC 60079-20-1: for methane 4.4% volume concentration for propane 1.7% vol, for iso-butane 1.3% volume concentration, calibrated in the production of iso-butane

Note: Not suitable for use with hydrogen

Gas detection standards met

  • EN 61779-1 (Electrical apparatus for the detection and measurement of flammable gases
  • EN 61779-4 (Electrical apparatus for the detection and measurement of flammable gases. Performance requirements for group II apparatus indicating a volume fraction up to 100% lower explosive limit)
  • EN 60079-10-1 (Explosive atmospheres. Classification of areas. Explosive gas atmospheres)
  • EN 50194-1 (Electrical apparatus for the detection of combustible gases in domestic premises. Test methods and performance requirements)
  • EN50130-4 (Alarm systems - Part 4: Electromagnetic compatibility)
  • EN55022 (Information technology equipment - Radio disturbance characteristics - Limits and methods of measurement)

LD-12 Water Leak Detector Features:

  • Operational temperature range:-10 to +40 °C
  • Output: Normally open and normally closed 200 mA max.
  • Power supply:12 V DC ± 15% ; 2 mA
  • Alarm condition: water flood
  • Supplied with 2.5m cable and screw mountings
  • Complies with:EN 50130-4, EN 55022

Smoke Detector Specification Summary

Feature Specification
Dimensions 100mm diameter, 45mm high
Power supply voltage 10.5V to 14V
Current consumption 32µA standby, 55mA when in alarm
Start up time 60 seconds (current consumption 80mA)
Protected area 40m2 maximum, 7m maximum height
Maximum air velocity 600m/minute
Testing - electronics Using a magnet
Testing - smoke Test Aerosol
Relay contacts rating 30V, 1A DC (0.5A, 125V AC)
Operating temperature 0°C to 70°C
IP protection IP42
Standards compliance EN54-7:2001
  • Power Egg
    Power Egg
  • GS-133 Gas Detector
    GS-133 Gas Detector
  • LD12 (trans)
    LD12 (trans)
  • Smoke Detector
    Smoke Detector
  • Door Contact Switch
    Door Contact Switch