Product Overview

The VQ500 Series is a range of miniature, fully certified, flameproof catalytic combustible gas sensor heads. Optimized for low power consumption, these sensors utilize a pellistor pair for detecting combustible gases and % volume gases via thermal conductivity. Their miniature electrochemical cell outline makes them ideal for portable instruments. The series offers sensors capable of detecting most combustible gases, vapors, and ammonia at LEL levels, as well as gases with thermal conductivities different from air at % volume concentrations. Specific variants undergo temperature testing for mining performance compliance (Group 1) and enhanced stability through burn-in.

Product Attributes

• Brand: SGX
• Series: VQ500
• Certifications: ATEX, IECEx, CSA, UL Recognized
• Material: Stainless Steel (Enclosure), Stainless Steel (Mesh), Epoxy Resin (Bushing)
• Poison Resistance: Silicones and Hydrogen Sulfide
• Shock Resistance: Yes (VQ548ZD variants)
• Origin: Poland

Technical Specifications

Model	Operating Voltage (V d.c)	Sensor Current (mA)	Minimum Sensitivity (mV/%Vol)	Offset (mV)	Routine Temperature Tested	Routine Burn-In and Drift Test	Outline	Description
VQ546M	4.25 0.1	50 60	-	-4.0 (1% Methane) 15	No	No	A	Low Power, Thermal Conductivity Sensor, methane. Negative output.
VQ546MR	4.25 0.1	50 60	-	+4.0 (1% Methane) 15	No	No	A	Low Power, Thermal Conductivity Sensor, methane. Positive output.
VQ547TS	3.0 0.1	40 50	21 (1.5% Ammonia) 30	-	Some	No	-	Low Power, LEL Ammonia Sensor.
VQ548ZD	3.0 0.1	67 80	20 (1% Methane) 20	-	No	No	B	Low Power, LEL methane sensor, silicone poisoning, H2S and Shock Resistant.
VQ548ZD/W	3.0 0.1	67 80	20 (1% Methane) 20	-	Yes	No	B	Low Power, LEL methane sensor, silicone poisoning, H2S and Shock Resistant.
VQ548ZD-S	3.0 0.1	67 80	20 (1% Methane) 20	-	No	Yes	B	Low Power, LEL methane sensor, silicone poisoning, H2S and Shock Resistant.
VQ549ZD	4.25 0.1	50 60	30 (1% Methane) 20	-	No	No	B	Low Power, LEL methane sensor, silicone poisoning, H2S and Shock Resistant.
VQ549ZD/W	4.25 0.1	50 60	30 (1% Methane) 20	-	Yes	No	B	Low Power, LEL methane sensor, silicone poisoning, H2S and Shock Resistant.
Environmental
Operating and Storage Temperature	40 to +55 C
Operating and Storage Humidity	0 to 80% (non-condensing)
Electrical
Supply Voltage	3.00 V to 4.25 V (Depending upon type)
Supply Power	135 mW to 230 mW (Depending upon type)
Performance
Linearity (Catalytic)	Linear up 60%LEL
Linearity (Thermal Conductivity)	Refer to Pellistor Application Note 5
Response Time (T90)	T90 < 20 seconds
Long Term Zero Drift (ZD-S Variants)	<5%LEL / month (based upon a 1 month period)
Long Term Zero Drift (All other Types)	<5%LEL / month (based upon a 12 month period)
Long Term Sensitivity Drift (ZD-S Variants)	<5%Full-Scale / month (based upon a 1 month period)
Long Term Sensitivity Drift (All other Types)	<5% Full-Scale / month (based upon a 12 month period)
Zero Offset with Temperature (ZD/W Variant Only)	0.2% methane variation between -10C to +40C when compared to the 20C reading
Warranty Period	12 months
Maximum Gas Concentrations
VQ546M, VQ546MR	100%v/v
VQ547TS, VQ548, VQ549	100%LEL
Mechanical
Dimensions	See outline, page 3
Weight	22g
Hazardous Area Installation Specifics
Maximum Output (Po) for Intrinsically Safe Supply	Not greater than 2.5 W
Maximum Surface Temperature Rise	Does not exceed 64 C
Impact Energy Resistance (Group I applications)	In excess of 7 J
Ambient Temperature Range for Use	40C and +55C