{"product_id":"watchgas-replacement-co-sensor-sst-spare-m","title":"WatchGas Replacement CO Sensor SST-SPARE-M","description":"\u003cp\u003e\u003cstrong\u003eWhen your CO sensor drifts, you don't replace the whole monitor. You swap the sensor cell.\u003c\/strong\u003e\u003c\/p\u003e\n\n\u003cp\u003eThat's the operational advantage of the serviceable WatchGas SST1 line. Traditional single-gas monitors are single-use — when the sensor reaches end-of-life or a bump test reveals unrecoverable drift, the whole unit gets discarded. The SST1 platform is designed to be maintained: this WatchGas Replacement CO Sensor drops into the \u003ca href=\"https:\/\/pksafety.com\/products\/watchgas-sst1-serviceable-co-gas-detector-sst1-m\"\u003eWatchGas SST1-M Serviceable CO Gas Detector\u003c\/a\u003e and any WatchGas SST4-series multi-gas monitor with CO in its standard 4-gas sensor set.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eCarbon monoxide is odorless, colorless, and tasteless.\u003c\/strong\u003e Workers get zero sensory warning that CO is accumulating in an enclosed space — not until the physiological effects kick in (headache, dizziness, confusion), and by then the exposure is already past regulatory limits and can escalate quickly. That physiology raises the stakes on sensor accuracy: a drifting CO sensor doesn't just mean an inconvenient recalibration — it means the monitor may not alarm before workers are already showing symptoms. For CO monitoring, sensor freshness is a life-safety input, not an inventory line item.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eWhat this sensor is (and isn't):\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eIt IS\u003c\/strong\u003e a factory replacement CO electrochemical sensor cell for the serviceable SST1-M monitor and any SST4-series multi-gas monitor (SST4-MINI, SST4-MICRO, SST4-PUMP). CO is standard in all three SST4 variants.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIt is NOT\u003c\/strong\u003e compatible with the Limited-Life \u003ca href=\"https:\/\/pksafety.com\/products\/watchgas-sst1-2-year-co-gas-detector-sst1-m-24\"\u003eSST1-M-24 (2-year)\u003c\/a\u003e or \u003ca href=\"https:\/\/pksafety.com\/products\/watchgas-sst1-3-year-co-gas-detector-sst1-m-36\"\u003eSST1-M-36 (3-year)\u003c\/a\u003e alert-only monitors — those are non-serviceable by design and are discarded at end-of-life. If you're using the alert-only variants, you replace the whole monitor, not the sensor.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIt is NOT\u003c\/strong\u003e a standalone gas detection device. The sensor cell requires a compatible WatchGas SST monitor to function.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003e\u003cstrong\u003eSolid polymer electrochemical sensor technology.\u003c\/strong\u003e The dry-cell design eliminates the liquid electrolyte used in traditional electrochemical sensors, giving the cell better long-term stability, no leak risk in truck-bed or field storage, and better tolerance for temperature extremes. Ultra-low power consumption compared to older CO sensor designs — one of the reasons the SST1-M can run for its full battery life without a mid-cycle charge.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eWhen to replace a CO sensor cell:\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eThe sensor fails a bump test and won't recover on recalibration\u003c\/li\u003e\n\u003cli\u003eCalibration drift exceeds acceptable tolerance across successive cal events\u003c\/li\u003e\n\u003cli\u003eThe monitor displays a sensor fault code specific to the CO channel\u003c\/li\u003e\n\u003cli\u003eThe sensor's warranty period (2 years) has elapsed and calibration reliability starts trending down\u003c\/li\u003e\n\u003cli\u003eYou're rotating a fleet's sensor generation on a proactive maintenance cadence — especially valuable for CO because sensor drift can silently defeat the monitor's core protective function\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003e\u003cstrong\u003eWho buys the SST-SPARE-M:\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eOwners of the WatchGas SST1-M serviceable CO monitor whose current sensor has drifted, failed a bump, or reached end-of-warranty\u003c\/li\u003e\n\u003cli\u003eOwners of the WatchGas SST4-MINI, SST4-MICRO, or SST4-PUMP multi-gas monitors whose CO channel needs replacement\u003c\/li\u003e\n\u003cli\u003eHVAC service companies, boiler operators, and heating contractors maintaining fleet monitors year-round\u003c\/li\u003e\n\u003cli\u003eFacility managers at garages, tunnels, parking structures, propane forklift operations — environments where CO exposure is a chronic hazard\u003c\/li\u003e\n\u003cli\u003eFire departments and post-fire investigation teams maintaining monitor accuracy for structural response work\u003c\/li\u003e\n\u003cli\u003eGrain drying operations, steel and foundry work, mining, and enclosed welding operations — industrial CO-exposure environments\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003e\u003cstrong\u003eSensor specifications:\u003c\/strong\u003e\u003c\/p\u003e\n\u003ctable\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eGas\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cstrong\u003eSensor technology\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cstrong\u003eWarranty\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cstrong\u003eCompatible monitors\u003c\/strong\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCO (carbon monoxide)\u003c\/td\u003e\n\u003ctd\u003eSolid polymer electrochemical (dry-cell)\u003c\/td\u003e\n\u003ctd\u003e2 years\u003c\/td\u003e\n\u003ctd\u003eSST1-M, SST4-MINI, SST4-MICRO, SST4-PUMP\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003cp\u003e\u003cstrong\u003eKey features:\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eHigh accuracy across the full detection range\u003c\/li\u003e\n\u003cli\u003eLong operational lifetime — 2-year warranty\u003c\/li\u003e\n\u003cli\u003eUltra-low power consumption (optimized for battery-operated and IoT-integrated monitors)\u003c\/li\u003e\n\u003cli\u003eHigh precision at low CO concentrations — critical for NIOSH REL-aligned monitoring (35 ppm TWA)\u003c\/li\u003e\n\u003cli\u003eNo zero drift\u003c\/li\u003e\n\u003cli\u003eSilicone-resistant (no poisoning by common industrial silicone contaminants)\u003c\/li\u003e\n\u003cli\u003eDirect linearity across the detection range\u003c\/li\u003e\n\u003cli\u003eHigh temperature range tolerance\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003e\u003cstrong\u003ePK Safety services the full WatchGas SST line with factory-trained technicians in-house.\u003c\/strong\u003e If you'd rather send the monitor to us for sensor replacement than swap the cell yourself, we handle that in-house — full swap, calibration verification against a certified CO standard, and return-to-service. We also service BW\/Honeywell (Factory Authorized Service Center), RKI, and RAE Systems monitors — one shop for a mixed-brand fleet's sensor lifecycle. Call us at \u003cstrong\u003e800.829.9580\u003c\/strong\u003e to talk through your CO sensor replacement workflow with someone who understands the SST1 \/ SST4 platform.\u003c\/p\u003e\n\n\u003cdiv class=\"specification\"\u003e\n\u003cp\u003e\u003cstrong\u003eTechnical documents (WatchGas SST1):\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003ca href=\"https:\/\/watchgas.com\/app\/uploads\/2024\/03\/SST1-brochure-1.1.pdf\" target=\"_blank\"\u003e\u003cimg border=\"0\" height=\"65\" width=\"63\" alt=\"Brochure\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0872\/5469\/6254\/files\/pdf-icon_ac4da377-e8e0-4a9c-9dcc-746269055096.png\"\u003e\u003c\/a\u003e \u003cstrong\u003eSST1 Brochure\u003c\/strong\u003e\u003c\/p\u003e\n\u003c\/div\u003e\n\n\u003cp\u003e\u003cstrong\u003ePart Number:\u003c\/strong\u003e WG01-SST-SPARE-M — WatchGas Replacement CO Sensor\u003c\/p\u003e\n\n\u003ch2\u003eFrequently Asked Questions\u003c\/h2\u003e\n\n\u003cdetails open\u003e\n\u003csummary\u003eWhich WatchGas monitors is the SST-SPARE-M sensor compatible with?\u003c\/summary\u003e\n\u003cp\u003eThe SST-SPARE-M is compatible with any WatchGas SST-platform monitor that includes a CO sensor slot:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003ca href=\"https:\/\/pksafety.com\/products\/watchgas-sst1-serviceable-co-gas-detector-sst1-m\"\u003eSST1-M Serviceable CO Gas Detector\u003c\/a\u003e — the single-gas CO monitor is designed around this sensor\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"https:\/\/pksafety.com\/products\/watchgas-sst4-mini-diffusion-4-gas-detector\"\u003eSST4-MINI Diffusion 4-Gas Detector\u003c\/a\u003e — CO is one of the four sensors in the standard configuration\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"https:\/\/pksafety.com\/products\/watchgas-sst4-micro-diffusion-4-gas-detector\"\u003eSST4-MICRO Diffusion 4-Gas Detector\u003c\/a\u003e — same CO sensor slot\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"https:\/\/pksafety.com\/products\/watchgas-sst4-pump-4-gas-detector\"\u003eSST4-PUMP 4-Gas Detector\u003c\/a\u003e — same CO sensor slot\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eThe SST-SPARE-M is NOT compatible with the Limited-Life \u003ca href=\"https:\/\/pksafety.com\/products\/watchgas-sst1-2-year-co-gas-detector-sst1-m-24\"\u003eSST1-M-24 (2-year)\u003c\/a\u003e or \u003ca href=\"https:\/\/pksafety.com\/products\/watchgas-sst1-3-year-co-gas-detector-sst1-m-36\"\u003eSST1-M-36 (3-year)\u003c\/a\u003e alert-only monitors — those are non-serviceable by design. When their sensors reach end-of-life, you replace the whole monitor, not the sensor cell.\u003c\/p\u003e\n\u003c\/details\u003e\n\n\u003cdetails open\u003e\n\u003csummary\u003eHow do I know it's time to replace my CO sensor?\u003c\/summary\u003e\n\u003cp\u003eFour common signals:\u003c\/p\u003e\n\u003col\u003e\n\u003cli\u003e\n\u003cstrong\u003eThe sensor fails a bump test\u003c\/strong\u003e and won't recover after recalibration. Bump testing before each use is the industry-standard way to verify sensor response; a persistent bump failure means the sensor cell is no longer detecting reliably.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCalibration drift exceeds acceptable tolerance\u003c\/strong\u003e across successive cal events. If each calibration is nudging the sensor's baseline further from the reference, the cell is degrading.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eThe monitor displays a sensor fault code\u003c\/strong\u003e specific to the CO channel. Cell exhaustion, extreme temperature or humidity exposure, or physical damage can trigger a fault.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eThe sensor is out of its warranty period.\u003c\/strong\u003e The SST-SPARE-M carries a 2-year warranty. Beyond that, sensor reliability trends down and proactive replacement is best practice — especially for CO, where sensor drift can silently defeat the monitor's core protective function.\u003c\/li\u003e\n\u003c\/ol\u003e\n\u003c\/details\u003e\n\n\u003cdetails open\u003e\n\u003csummary\u003eWhy does CO sensor drift matter more than drift on other gases?\u003c\/summary\u003e\n\u003cp\u003eCarbon monoxide is odorless, colorless, and tasteless. Unlike H2S (rotten-egg smell at low ppm), ammonia (pungent), or sulfur dioxide (sharp acid smell), CO gives workers zero sensory warning that concentrations are building up. Symptoms of CO exposure — headache, dizziness, confusion, nausea — typically don't kick in until concentrations are already past regulatory limits, and CO poisoning can escalate quickly.\u003c\/p\u003e\n\u003cp\u003eThat physiology has one operational implication for CO monitoring: the monitor isn't a backup to what workers can already sense. It IS the warning system. If the CO sensor drifts and the monitor no longer alarms at the intended threshold, workers won't notice a substitute warning — they'll notice symptoms. For CO monitoring more than any other gas in the SST platform, proactive sensor replacement on a defined cadence is worth the discipline.\u003c\/p\u003e\n\u003c\/details\u003e\n\n\u003cdetails open\u003e\n\u003csummary\u003eCan I install the SST-SPARE-M myself, or do I need to send the monitor to PK Safety?\u003c\/summary\u003e\n\u003cp\u003eBoth paths work. The SST1 platform is designed for user sensor replacement — the sensor cell is accessed through the monitor's service compartment, and the WatchGas SST1 manual walks through the swap procedure. After installation, you'll need to complete a full calibration to verify the new sensor's response against a known CO standard.\u003c\/p\u003e\n\u003cp\u003eIf you'd rather not run the swap yourself — for example, if you don't have a calibration workflow set up, or if you want a factory-trained technician to verify the sensor's performance across its full range before it goes back into service — send the monitor to PK Safety. We handle the swap, full calibration verification, and return-to-service in-house.\u003c\/p\u003e\n\u003c\/details\u003e\n\n\u003cdetails open\u003e\n\u003csummary\u003eShould I replace the sensor or buy a new SST1-M monitor?\u003c\/summary\u003e\n\u003cp\u003eThe SST-SPARE-M sensor cell costs $160. A full new \u003ca href=\"https:\/\/pksafety.com\/products\/watchgas-sst1-serviceable-co-gas-detector-sst1-m\"\u003eSST1-M monitor\u003c\/a\u003e costs $370. If your monitor's housing, display, battery, and electronics are in good working order and only the CO sensor has drifted or reached end-of-life, the sensor replacement is the more cost-effective path — roughly 43% of the full-monitor price for the maintenance action that gets your fleet back to compliance.\u003c\/p\u003e\n\u003cp\u003eIf the monitor itself has physical damage, a battery that no longer holds charge, or a display that's failing, a full monitor replacement is the better path. PK Safety can help you evaluate — call 800.829.9580 with your monitor's condition and we'll walk you through the choice.\u003c\/p\u003e\n\u003c\/details\u003e\n\n\u003cdetails open\u003e\n\u003csummary\u003eHow is the SST-SPARE-M calibrated after installation?\u003c\/summary\u003e\n\u003cp\u003eAfter installing the new sensor cell in the monitor, run a full calibration cycle using a CO calibration gas standard. For multi-gas monitors, use the \u003ca href=\"https:\/\/pksafety.com\/products\/pk-safety-watchgas-equivalent-4-gas-calibration-gas-mix-34-liter\"\u003ePK Safety WatchGas Equivalent 4-Gas Calibration Gas Mix\u003c\/a\u003e (contains LEL, O2, CO, H2S at cal-standard concentrations). For a dedicated single-gas cal, use a standalone CO cylinder (typically 50 ppm CO in air balance).\u003c\/p\u003e\n\u003cp\u003eAutomated calibration is fastest using the \u003ca href=\"https:\/\/pksafety.com\/products\/watchgas-docking-station-w-touchscreen-sst-dock\"\u003eWatchGas SST-DOCK Touchscreen docking station\u003c\/a\u003e — one docking cycle handles bump test and full calibration in about 60 seconds. Manual calibration through the monitor's menu also works if the SST-DOCK isn't part of your workflow.\u003c\/p\u003e\n\u003c\/details\u003e\n\n\u003cp\u003e\u003cstrong\u003eNot sure whether a sensor swap or full monitor replacement is the right path? Call PK Safety at 800.829.9580.\u003c\/strong\u003e A person who knows the SST platform's service ecosystem will pick up.\u003c\/p\u003e","brand":"WatchGas","offers":[{"title":"Default Title","offer_id":52671727960431,"sku":"WG01-SST-SPARE-M","price":160.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0872\/5469\/6254\/files\/SST-SPARE-M---Watchgas-SST-sensor-CO-0-1000ppm-for-all---3---K1E800x800compressed.jpg?v=1771007939","url":"https:\/\/pksafety.com\/products\/watchgas-replacement-co-sensor-sst-spare-m","provider":"PK Safety Supply","version":"1.0","type":"link"}