Product Overview

The SGX VQ21T Series Combustible Gas Sensor Elements are highly poison-resistant, low-voltage detectors designed for fixed systems. Utilizing the catalytic oxidation principle, these pellistors are ideal for general-purpose applications where power consumption is a consideration. They can detect a wide range of flammable gases and vapors, including methane in air mixtures from 0.1% to 5% (100% LEL). The VQ21T Series features significant improvements in pellistor bead structure, offering superior resistance to poisoning, particularly from silicones, and providing a considerably longer operational life compared to standard VQ1 pellistors.

Product Attributes

• Brand: SGX Sensortech
• Series: VQ21T Series
• Principle: Catalytic Oxidation
• Poison Resistance: Highly poison resistant, particularly to silicones
• Power: Low voltage
• Application: Fixed systems, general purpose
• Detection: Most flammable gases and vapors, Methane (0.1% - 5% in air)
• Expected Operating Life: >5 years

Technical Specifications

Specification	Value
Gases Detected	Flammable gases and vapors
Expected Operating Life	>5 years
Bridge Supply Voltage	2.0 + 0.1 V
Sensor Current (typical)	300 mA
Sensor Power Consumption (max)	750 mW
Minimum Sensitivity (note 1)	15 mV/%
Linearity	Linear up to 3% CH4
Response Time (t50) (note 2)	2 secs
Typical Max. Gas Concentration (note 3)	100% LEL
Operational Temperature	-40C to +70C
Storage Temperature	+10C to +25C
Pressure	1 Atm. +/-10%
Humidity	0-80% RH (Non-condensing)
Orientation	Any
Shock Test (note 4)	250 g, 5 blows in each plane
Vibration Test (note 4)	20 g, 24 cycles, 100 to 3200 Hz
Models & Options
VQ21TB (PCB Legs)	Included
VQ21TSB (PCB Legs, Hydrogen mods)	Included
Outline Dimensions (VQ21TB & VQ21TSB)
A (max)	11.3 mm (0.445 in)
A (min)	10.8 mm (0.425 in)
B (max)	6.35 mm (0.250 in)
B (min)	5.85 mm (0.230 in)
C (max)	3.69 mm (0.145 in)
C (min)	3.43 mm (0.135 in)
D (min)	40.0 mm (1.575 in)
E (nom)	1.0 mm (0.039 in)
F (max)	7.88 mm (0.310 in)
F (min)	6.86 mm (0.270 in)
G (max)	8.2 mm (0.323 in)
H (nom)	1.5 mm (0.059 in)