Forensics Detectors 4 Gas Meter for Confined Space (O2, CO, H2S, LEL)

Forensics Detectors 4 Gas Meter — Confined-Space O2, CO, H2S & LEL Monitor

The Forensics Detectors 4 gas meter is a NIST-calibrated, confined-space-ready monitor that reads oxygen (O2), combustible gas (LEL), carbon monoxide (CO) and hydrogen sulfide (H2S) in one pass — the four-hazard set portable gas detector buyers need for permit entry. At 4.8 oz with triple alarms, it is built for field crews who want documented accuracy without a fleet-management contract.

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The Forensics Detectors 4 Gas Meter is a battery-powered, electrochemical four-gas monitor (O2, CO, H2S, LEL) with a NIST calibration certificate, designed for portable confined-space pre-entry testing.

Key features

• Reads all four confined-space hazards — oxygen (O2), combustible gas (LEL), carbon monoxide (CO) and hydrogen sulfide (H2S) — on one screen
• Ships with a USA NIST calibration certificate so you can document instrument accuracy from day one
• Triple alarm — adjustable audible, visual LED and vibration — for noisy or low-visibility work
• Electrochemical nano sensors with zero and span calibration options for ongoing accuracy
• Rugged anti-slip ABS housing that is water-resistant, dust-proof and explosion-resistant
• Light 4.8 oz body that clips to a belt or harness for pre-entry checks

Specifications

Where the Forensics Detectors 4 Gas Meter fits

• Confined-space pre-entry atmosphere checks
• Sewer, vault and manhole spot tests
• Tank and vessel entry monitoring
• HVAC, boiler and mechanical-room checks
• General industrial walk-around monitoring

What the Forensics Detectors 4 Gas Meter detects (and what it doesn’t)

This meter measures oxygen (O2), combustible gas (LEL), carbon monoxide (CO) and hydrogen sulfide (H2S) — the standard four-gas set for confined-space entry. It does not read volatile organic compounds (VOCs), CO2, or single toxics such as chlorine or ammonia; those need a dedicated PID or gas-specific sensor. It uses diffusion sampling, so it reads the air around it — to draw a remote sample from the bottom of a tank before entry, choose the Forensics Detectors 4 Gas Monitor with Pump instead. Keep it accurate with zero/span calibration and a periodic bump test using standard four-gas calibration gas. For all-shift single-worker wear, pair it with a clip from Personal & Wearable Gas Detectors.

Cross-shopping? This unit sits in our Portable Gas Detectors hub alongside the Forensics Detectors USB 4 Gas Monitor, TopTes Guard-863Pro, TopTes Guard-101, TopTes Guard-156. If one worker needs all-shift wear instead of a carried meter, see Personal & Wearable Gas Detectors; for a fixed install or a job-site perimeter, see Fixed Gas Detection Systems and Area & Transportable Gas Monitors.

Forensics Detectors 4-gas family compared

• Choose this 4 Gas Meter for the lightest, lowest-cost NIST-certified diffusion unit for routine pre-entry checks.
• Step up to the USB-rechargeable 4 Gas Monitor if you want USB charging and a higher review count.
• Move to the 4 Gas Monitor with Pump if you must sample remotely before entry.

Frequently asked questions

What gases does the Forensics Detectors 4 gas meter detect?

It detects oxygen (O2), combustible gas (LEL), carbon monoxide (CO) and hydrogen sulfide (H2S) — the four atmospheric hazards required for confined-space entry. For VOCs you need a separate PID unit; browse the full Portable Gas Detectors range for options.

Is the Forensics Detectors 4 gas meter NIST calibrated?

Yes — it ships with a USA NIST calibration certificate documenting instrument accuracy at the time of calibration. You should still bump-test before each use.

How do I calibrate and bump-test this meter?

Use standard four-gas calibration gas with the zero and span calibration functions. Bump-test before each day of use to confirm the sensors and alarms respond; do a full calibration on the manufacturer's schedule.

Can I use this for confined-space entry?

Yes — its O2/CO/H2S/LEL set matches the hazards OSHA 1910.146 names for permit entry. For pre-entry sampling of a sealed space, the pump version lets you test before anyone enters.

Does it have a pump or is it diffusion?

This model is diffusion — it reads the air around it. If you need to draw a remote sample through a probe, choose the Forensics Detectors 4 Gas Monitor with Pump.

How is it powered and how long does it run?

It runs on a rechargeable internal battery sized for a full work shift. Recharge between shifts so it is always ready for pre-entry checks.

What alarms does it have?

Adjustable audible, visual LED and vibration alarms trip when a gas reaches its preset level — useful in loud or low-visibility environments.

How long do the sensors last?

The electrochemical sensors typically last two to three years depending on exposure. Budget for sensor replacement and calibration gas as ongoing costs.

What does this meter NOT detect?

It does not read VOCs, CO2, or specific toxics like chlorine or ammonia. For those, a PID or gas-specific instrument is required — see the wider Portable Gas Detectors hub.

Is it in stock and how does it ship?

Stocked items ship through our Amazon fulfillment partner; use the buy button for current availability and delivery timing.

How does it compare to the USB-rechargeable Forensics monitor?

Both read the same four gases with NIST certificates; the USB 4 Gas Monitor adds USB charging and has more reviews, while this meter is lighter and lower cost.

Is this an industrial-grade instrument?

It is a NIST-certified field meter well suited to small crews and facilities. Large managed-fleet programs that need docking-station automation usually specify Industrial Scientific or BW Honeywell instruments.