SKU: WG01-SST-M-RPL

WatchGas Replacement CO Sensor SST-M-RPL

$160.00

Ships in 2 - 3 weeks

Description

When your CO sensor drifts, you don't replace the whole monitor. You swap the sensor cell.

That'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 WatchGas SST1-M Serviceable CO Gas Detector and any WatchGas SST4-series multi-gas monitor with CO in its standard 4-gas sensor set.

Carbon monoxide is odorless, colorless, and tasteless. 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.

What this sensor is (and isn't):

It IS 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.
It is NOT compatible with the Limited-Life SST1-M-24 (2-year) or SST1-M-36 (3-year) 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.
It is NOT a standalone gas detection device. The sensor cell requires a compatible WatchGas SST monitor to function.

Solid polymer electrochemical sensor technology. 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.

When to replace a CO sensor cell:

The sensor fails a bump test and won't recover on recalibration
Calibration drift exceeds acceptable tolerance across successive cal events
The monitor displays a sensor fault code specific to the CO channel
The sensor's warranty period (2 years) has elapsed and calibration reliability starts trending down
You'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

Who buys the SST-M-RPL:

Owners of the WatchGas SST1-M serviceable CO monitor whose current sensor has drifted, failed a bump, or reached end-of-warranty
Owners of the WatchGas SST4-MINI, SST4-MICRO, or SST4-PUMP multi-gas monitors whose CO channel needs replacement
HVAC service companies, boiler operators, and heating contractors maintaining fleet monitors year-round
Facility managers at garages, tunnels, parking structures, propane forklift operations — environments where CO exposure is a chronic hazard
Fire departments and post-fire investigation teams maintaining monitor accuracy for structural response work
Grain drying operations, steel and foundry work, mining, and enclosed welding operations — industrial CO-exposure environments

Sensor specifications:

Gas	Sensor technology	Warranty	Compatible monitors
CO (carbon monoxide)	Solid polymer electrochemical (dry-cell)	2 years	SST1-M, SST4-MINI, SST4-MICRO, SST4-PUMP

Key features:

High accuracy across the full detection range
Long operational lifetime — 2-year warranty
Ultra-low power consumption (optimized for battery-operated and IoT-integrated monitors)
High precision at low CO concentrations — critical for NIOSH REL-aligned monitoring (35 ppm TWA)
No zero drift
Silicone-resistant (no poisoning by common industrial silicone contaminants)
Direct linearity across the detection range
High temperature range tolerance

PK Safety services the full WatchGas SST line with factory-trained technicians in-house. 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 800.829.9580 to talk through your CO sensor replacement workflow with someone who understands the SST1 / SST4 platform.

Technical documents (WatchGas SST1):

SST1 Brochure

Part Number: WG01-SST-M-RPL — WatchGas Replacement CO Sensor

Frequently Asked Questions

Which WatchGas monitors is the SST-M-RPL sensor compatible with?

The SST-M-RPL is compatible with any WatchGas SST-platform monitor that includes a CO sensor slot:

SST1-M Serviceable CO Gas Detector — the single-gas CO monitor is designed around this sensor
SST4-MINI Diffusion 4-Gas Detector — CO is one of the four sensors in the standard configuration
SST4-MICRO Diffusion 4-Gas Detector — same CO sensor slot
SST4-PUMP 4-Gas Detector — same CO sensor slot

The SST-M-RPL is NOT compatible with the Limited-Life SST1-M-24 (2-year) or SST1-M-36 (3-year) 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.

How do I know it's time to replace my CO sensor?

Four common signals:

The sensor fails a bump test 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.
Calibration drift exceeds acceptable tolerance across successive cal events. If each calibration is nudging the sensor's baseline further from the reference, the cell is degrading.
The monitor displays a sensor fault code specific to the CO channel. Cell exhaustion, extreme temperature or humidity exposure, or physical damage can trigger a fault.
The sensor is out of its warranty period. The SST-M-RPL 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.

Why does CO sensor drift matter more than drift on other gases?

Carbon 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.

That 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.

Can I install the SST-M-RPL myself, or do I need to send the monitor to PK Safety?

Both 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.

If 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.

Should I replace the sensor or buy a new SST1-M monitor?

The SST-M-RPL sensor cell costs $160. A full new SST1-M monitor 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.

If 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.

How is the SST-M-RPL calibrated after installation?

After 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 PK Safety WatchGas Equivalent 4-Gas Calibration Gas Mix (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).

Automated calibration is fastest using the WatchGas SST-DOCK Touchscreen docking station — 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.

Not sure whether a sensor swap or full monitor replacement is the right path? Call PK Safety at 800.829.9580. A person who knows the SST platform's service ecosystem will pick up.