High sensitivity methane gas detection element Amphenol VQ21B suitable for industrial safety systems

Product Overview

The VQ21 is an improved, poison-resistant combustible gas detector element designed for the detection of combustible gases, particularly methane in air mixtures from 0.1% upwards. It offers no interference from water vapour or carbon dioxide and is suitable for use in atmospheres where traces of silicone and other poisoning agents may be present. When used with the recommended bridge circuit and mounting arrangement, it achieves a minimum sensitivity of 10 mV/% methane. The VQ21 is designed for continuous operation and can detect methane concentrations up to 5% with a fast response time.

Product Attributes

• Brand: SGX Sensortech
• Model: VQ21
• Element Type: Combustible Gas Detector
• Detector Sleeve Color: Red
• Compensator Sleeve Color: Black
• Origin: Registered in England
• Issue: A1A-VQ21 Issue 4, March 2007

Technical Specifications

Specification	Value	Notes
Operation	Continuous	May be under direct flow or diffusion conditions in appropriate mountings.
Bridge Supply	2.0 + 0.1 V
Bridge Power Consumption	0.75 W max
Typical Average Sensor Current	300 mA
Minimum Sensitivity	10 mV/% methane	With open-circuit conditions at the bridge output.
Linearity	Linear up to 5% methane
Response Time	2 seconds	To register 1 1/4% in a 2 1/2% concentration. Function of mounting type.
Maximum Methane Concentration	5 %	Calibration should be checked if exposed to >5% methane.
Mounting	See page 3
Outline	See page 3
Trimming Resistor (R)	Supplied where necessary	To be connected across the compensator element.
Resistance to Silicone Poisoning	Partly dependent on housing type	Results shown obtained using flow housing on page 3.
Response to Heavy Flammable Vapours	May be lower than calculated	Especially aromatic substances with side chains.

Outline Dimensions (Nominal)

Ref	Millimetres
A	11.05 + 0.25
B	6.10 + 0.25
C	3.56 + 0.13
D	63.50 min
E	1.02
F	7.37 + 0.51
G	8.20 max
H	9.53
J	1.52

Recommended Mounting Arrangements

Ref	Millimetres
AA	19.05 max
AB	9.53 + 0.13
AC	8.33 + 0.13
AD	8.20 min
AE	19.05 max
AF	9.53 + 0.13
AG	8.20 min

2411261432_Amphenol-VQ21B_C3659317.pdf

High sensitivity methane gas detection element Amphenol VQ21B suitable for industrial safety systems Images