CITY MICROPEL 75 75C PM759-000 PM769-000 Combustible gas sensor

CITY MICROPEL 75 75C PM759-000 PM769-000 Combustible gas sensor

Parameters
Brand: City
Model: 75 75C
Principle: Catalytic oxidation (Pellistor), used to detect the lower limit of combustible gas explosion (LEL).
Origin: UK
1. Testing performance
Range: 0~100% LEL (Methane 0~5% VOL)
Target gases: light combustible hydrocarbons such as methane, ethane, propane, butane, hydrogen, and CO
Not suitable for: high carbon hydrocarbons, alcohols, ketones, esters, high concentrations of H₂S
Sensitivity: 31±5 mV/% methane
T90 Response Time: <5s (Methane)
Linear interval: 0~3% methane with excellent linearity
Resolution: 1% LEL
Anti-poisoning: Enhanced anti-silicone and hydrogen sulfide resistance; The filter has a total capacity of 1000 ppm·hr H₂S
Filter lifespan: Normal operating conditions> 5 years
2. Electrical parameters
Rated power supply: 3.30 VDC ±0.02V
Operating current: 78±6 mA
Maximum power consumption: 295 mW
Structure: Dual beads (Detector beads, Compensator beads), 3-pin output
3. Environment and Machinery
Operating temperature: -20°C ~ 55°C
Temperature and humidity: 0~90% RH, non-condensing
Pressure: Standard atmospheric pressure ±20%
Weight: 2g
Installation: Azimuth sensitivity, usable at any angle
Housing: 316 stainless steel, IP6X protection
4. Lifespan and drift
Expected service life: 5 years in air
Long-term range drift: <5% signal per month
Zero drift: <5% LEL methane per month

3. Core differences between the 75 and 75C
75C adds a dedicated H₂S filter layer, greatly improving the environmental lifespan of sulfides and silicones; The 75 Standard Edition lacks a reinforced filter layer, making it prone to poisoning and failure
75C fully certified ATEX/UL explosion-proof components, suitable for industrial explosion-proof equipment; 75 Basic model certification simplified
75C is the universal standard for portable four-in-one/two-in-one gas detectors (BW, Honeywell instruments).
4. Typical Application Scenarios
Portable Composite Gas Detector (LEL Combustible Channel)
Natural gas and gas pipeline leak inspection instruments
LEL monitoring in underground utility tunnels, ship holds, gas stations, and chemical workshops
Safety inspection for confined space operations
5. Precautions for Use
A 3.3V constant voltage driver circuit must be used; direct 5V power supply is not allowed, as it will burn out the catalytic beads
Silicone gel, silicone oil, and high concentrations of H₂S can permanently poison catalytic beads, so avoid them on site
Long-term high-temperature/high-humidity condensation accelerates zero drift; it is recommended to calibrate every 3~6 months
The sensor must not be disassembled, and the internal lead acetate filter layer may be damaged, posing contact hazards
Sensitivity slightly decreases in low-temperature environments below 0°C; software compensation is required for low-temperature use
6. Pin Definition (3Pin)
DETECTOR: Detection beads
COMPENSATOR: Compensation beads
V: 3.3V power supply positive terminal

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