Product Overview
The SGX Sensortech VQ3 is a catalytic flammable gas sensor, also known as a pellistor, designed for detecting a wide range of combustible gases in air. It operates within concentrations from 0% to 100% of the Lower Explosive Limit (LEL) for a given gas. The VQ3 is an established, general-purpose sensor for fixed gas detection systems, prioritizing low cost and stability. It is suitable for continuous or intermittent operation and is supplied as a matched pair of elements with a trimming resistor.
Product Attributes
- Brand: SGX Sensortech
- Type: Catalytic flammable gas sensor (pellistor)
- Identification: Active (detector) device has a dark bead and a red serial number on its metal can. Compensator has a white bead and a black serial number on its metal can.
Technical Specifications
| Specification | Value | Notes |
|---|---|---|
| Model | VQ3 | Standard device, with stranded flexible leads. |
| Model | VQ3AA | Optimised for use with constant current circuitry operating at 300 mA. |
| Model | VQ3B | Supplied with pcb compatible leads. |
| Model | VQ3BJ | VQ3B with size 1206 chip resistor instead of standard wire ended resistor. |
| Operation | Continuous or intermittent | |
| Bridge Supply | 2.5 + 0.1 V | |
| Typical Bridge Current | 330 mA | |
| Minimum Sensitivity | 21 mV/% methane | |
| Linearity | Within 5% of reading up to 60% LEL (methane) | See Note 1 for further details. |
| Repeatability | 2% LEL (methane) | |
| Response Time (T50) | 2 seconds | Measured at 50% LEL methane. |
| Maximum Methane Concentration | 10% | See Note 2. Calibration check recommended if exposed to >100% LEL. |
| Typical Long Term Drift (Zero) | 0.5 mV/month | Assumes no exposure to poisoning chemicals. See Note 3. |
| Typical Long Term Drift (Span) | 2% signal/month | Assumes no exposure to poisoning chemicals. See Note 3. |
| Shock Test | 250 g, 5 blows in each plane | |
| Vibration Test | 20 g, 24 cycles from 100 to 3200 Hz | |
| Outline (VQ3, VQ3AA) Dimension A | 11.05 + 0.25 mm (0.435 + 0.010 in) | |
| Outline (VQ3, VQ3AA) Dimension B | 6.10 + 0.25 mm (0.240 + 0.010 in) | |
| Outline (VQ3, VQ3AA) Dimension C | 3.56 + 0.13 mm (0.140 + 0.005 in) | |
| Outline (VQ3, VQ3AA) Dimension D | 63.5 min (2.500 min) | |
| Outline (VQ3, VQ3AA) Dimension E | 1.0 mm (0.039 in) | |
| Outline (VQ3, VQ3AA) Dimension F | 5.84 + 0.51 mm (0.230 + 0.020 in) | |
| Outline (VQ3, VQ3AA) Dimension G | 8.20 max (0.323 max) | |
| Outline (VQ3, VQ3AA) Dimension H | 9.53 mm (0.375 in) | |
| Outline (VQ3, VQ3AA) Dimension J | 1.5 mm (0.059 in) | |
| Outline (VQ3B, VQ3BJ) Dimension A | 11.05 + 0.25 mm (0.435 + 0.010 in) | |
| Outline (VQ3B, VQ3BJ) Dimension B | 6.10 + 0.25 mm (0.240 + 0.010 in) | |
| Outline (VQ3B, VQ3BJ) Dimension C | 3.56 + 0.13 mm (0.140 + 0.005 in) | |
| Outline (VQ3B, VQ3BJ) Dimension D | 40.0 mm (1.575 in) | |
| Outline (VQ3B, VQ3BJ) Dimension E | 1.0 mm (0.039 in) | |
| Outline (VQ3B, VQ3BJ) Dimension F | 5.84 + 0.51 mm (0.230 + 0.020 in) | |
| Outline (VQ3B, VQ3BJ) Dimension G | 8.20 max (0.323 max) | |
| Outline (VQ3B, VQ3BJ) Dimension H | 1.5 mm (0.059 in) | |
| Trimming Resistor | Not less than 39 | Connected across the compensator element. |
Note 1: Further details on linearity corrections may be found in SGX Sensortech Pellistor Application Note 4.
Note 2: If the VQ3 is exposed to greater than 100% LEL concentration of a flammable gas whilst operating, the calibration of the instrument should be checked.
Note 3: Some flammable gases and vapours (e.g., silicones, fuel additives, sulphur-bearing compounds) can damage or poison pellistors. Long-term drift data assumes no exposure to such chemicals. Refer to SGX Sensortech Pellistor Application Note 6 for guidance on Pellistor Poisoning.
Note 4: The choice of 1 k for balancing resistors is arbitrary and assumes a high impedance measuring device. Lower impedance loads may require lower value balancing resistors.
Warning: SGX Sensortech recommends the use of a suitable flame arrestor for safe operation, regulatory compliance, and approval requirements.
2411261432_Amphenol-VQ3BJ_C3659315.pdf
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