SKU: WG01-SST-O-RPL

WatchGas Replacement O2 Sensor SST-O-RPL

$160.00

Ships in 2 - 3 weeks

Description

When your O2 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 O2 Sensor drops into the WatchGas SST1-O Serviceable O2 Gas Detector and any WatchGas SST4-series multi-gas monitor with O2 in its standard 4-gas sensor set.

Oxygen deficiency is silent. The gases that displace oxygen from an enclosed space — nitrogen, argon, helium, CO2, methane — are themselves colorless and odorless. Workers get zero sensory warning that the atmosphere they're breathing has become dangerous. Cognitive impairment begins around 16% oxygen; by 12%, workers may not recognize the danger they're in. For O2 monitoring more than any other gas, sensor accuracy is the difference between recognizing a hypoxic environment and getting caught by it. A drifting O2 sensor doesn't warn you it's drifting — it just quietly stops flagging the atmosphere that will impair you.

What this sensor is (and isn't):

It IS a factory replacement O2 electrochemical sensor cell for the serviceable SST1-O monitor and any SST4-series multi-gas monitor (SST4-MINI, SST4-MICRO, SST4-PUMP). O2 is standard in all three SST4 variants.
It is NOT compatible with the Limited-Life SST1-O-24 (2-year) alert-only monitor — that one is non-serviceable by design and is discarded at end-of-life. If you're using the alert-only variant, you replace the whole monitor, not the sensor. (There is no 3-year alert-only O2 variant in the SST1 line — O2 is a two-tier product family.)
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 O2 sensor designs.

When to replace an O2 sensor cell:

The sensor fails a bump test and won't recover on recalibration
Fresh-air calibration drift exceeds acceptable tolerance across successive cal events
The monitor displays a sensor fault code specific to the O2 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 O2 because sensor drift can silently defeat the monitor's core protective function against hypoxic environments

Who buys the SST-O-RPL:

Owners of the WatchGas SST1-O serviceable O2 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 O2 channel needs replacement
Confined-space entry teams (petrochemical, water/wastewater, industrial manufacturing) whose SOP requires accurate O2 monitoring before entry
Cryogenics operators (LOX / liquid nitrogen / liquid argon boil-off environments)
Food and beverage plants running inert-atmosphere packaging (N2 purging can silently displace room O2 in enclosed process areas)
Breweries and wineries where fermentation CO2 can accumulate in cellars, tanks, and closed process spaces
Semiconductor fabs with N2 purge environments
Pharmaceutical facilities operating inert-atmosphere reactors
Medical gas facilities storing or handling compressed inert gases
Fire investigation teams and industrial rescue crews maintaining monitor accuracy for post-fire, mine, and confined-space response

Sensor specifications:

Gas	Sensor technology	Warranty	Compatible monitors
O2 (oxygen)	Solid polymer electrochemical (dry-cell)	2 years	SST1-O, SST4-MINI, SST4-MICRO, SST4-PUMP

Key features:

High accuracy across the full detection range (0–25% O2)
Long operational lifetime — 2-year warranty
Ultra-low power consumption (optimized for battery-operated and IoT-integrated monitors)
High precision at the OSHA 19.5% oxygen-deficient threshold — critical for confined-space entry compliance
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, fresh-air and span calibration verification, 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 O2 sensor replacement workflow with someone who understands the SST1 / SST4 platform.

Technical documents (WatchGas SST1):

SST1 Brochure

Part Number: WG01-SST-O-RPL — WatchGas Replacement O2 Sensor (2-year warranty)

Frequently Asked Questions

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

The SST-O-RPL is compatible with any WatchGas SST-platform monitor that includes an O2 sensor slot:

SST1-O Serviceable O2 Gas Detector — the single-gas O2 monitor is designed around this sensor
SST4-MINI Diffusion 4-Gas Detector — O2 is one of the four sensors in the standard configuration
SST4-MICRO Diffusion 4-Gas Detector — same O2 sensor slot
SST4-PUMP 4-Gas Detector — same O2 sensor slot

The SST-O-RPL is NOT compatible with the Limited-Life SST1-O-24 (2-year) alert-only monitor — that one is non-serviceable by design. There is no 3-year alert-only O2 variant in the SST1 line, so if you're using the SST1-O-24, replacement means a whole new monitor.

How do I know it's time to replace my O2 sensor?

Four common signals:

The sensor fails a bump test or a fresh-air calibration — the monitor shows a reading materially different from 20.9% O2 in a known-clean atmosphere.
Fresh-air calibration drift exceeds acceptable tolerance across successive cal events. If each fresh-air cal is drifting further from 20.9%, the cell is degrading.
The monitor displays a sensor fault code specific to the O2 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-O-RPL carries a 2-year warranty. Beyond that, sensor reliability trends down and proactive replacement is best practice — especially for O2, where a drifting sensor is silently exposing workers to hypoxic conditions with no compensating sensory warning.

Why does O2 sensor drift matter more than drift on other gases?

Because oxygen deficiency is silent. The gases that displace O2 in confined spaces — nitrogen, argon, helium, CO2, methane — are colorless and odorless. Workers get no sensory warning that the atmosphere is going hypoxic. Cognitive impairment begins around 16% O2; by the time O2 drops to 12%, workers may not recognize the danger they're in. Loss of consciousness follows quickly.

That physiology has one operational implication for O2 monitoring: the monitor is your only reliable warning system. If the O2 sensor drifts and the monitor no longer alarms at OSHA's 19.5% oxygen-deficient threshold, workers won't feel a substitute warning — they'll experience impairment. For O2 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-O-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 fresh-air calibration (in a known-clean atmosphere at 20.9% O2) and ideally a span calibration using a known O2 concentration cal gas.

If you'd rather not run the swap yourself, 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-O monitor?

Honest answer: this is closer than the H2S or CO cases. The SST-O-RPL sensor cell costs $160. A full new SST1-O monitor costs $210. The sensor swap saves you $50 vs. a full new monitor — real, but modest.

The economic case is strongest when:

Your existing monitor's housing, battery, display, and electronics are still in good working order
You want to preserve the remaining useful life of the current monitor's non-sensor components
You already have a calibration workflow set up for sensor swaps

The full-monitor replacement case is stronger when:

The monitor itself is aging (battery no longer holds full charge, display or housing showing wear)
You don't have a sensor-swap calibration workflow in place
You want a fresh 3-year instrument warranty on top of the 2-year sensor warranty

Call PK Safety at 800.829.9580 with your monitor's condition and we'll walk you through the choice.

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

O2 calibration has two steps that are slightly different from toxic-gas calibration:

Fresh-air calibration: in a known-clean atmosphere at 20.9% O2 (outside, or a verified breathing-air source), the monitor's fresh-air cal sets the sensor's baseline. This is the most important step for O2.
Span calibration (optional but recommended): using an O2 calibration cylinder at a known concentration (typically 18% O2 in balance gas) to verify the sensor's response across the low-O2 alarm threshold.

Automated calibration is fastest using the WatchGas SST-DOCK Touchscreen docking station — one docking cycle handles fresh-air cal and bump test in about 60 seconds. For span cal, the PK Safety WatchGas Equivalent 4-Gas Calibration Gas Mix includes an O2-below-19.5% component for span verification, or use a dedicated O2 span cylinder.

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.