{"product_id":"forensics-detectors-4-gas-meter-confined-space","title":"Forensics Detectors 4 Gas Meter for Confined Space (O2, CO, H2S, LEL)","description":"\u003c!-- PRODUCT B0GNQ37S9C | tag portable-gas-detector | TODO: add matching Product Review + best-of guide links when those silo layers exist --\u003e\n\n\u003cdiv style=\"background:#1a1a1a;border-left:4px solid #ff9800;padding:14px 18px;margin:0 0 18px 0;color:#f5e6d3;font-size:0.95em;\"\u003e\n\u003cstrong style=\"color:#ffb74d;\"\u003eEditor’s note:\u003c\/strong\u003e the Forensics Detectors 4 gas meter is one of the portable instruments we curate in our \u003ca href=\"\/collections\/portable-gas-detectors\" title=\"Portable Gas Detectors\"\u003ePortable Gas Detectors\u003c\/a\u003e buyer’s hub. Compare it head-to-head with the \u003ca href=\"\/products\/forensics-detectors-4-gas-monitor-usb-rechargeable\" title=\"Forensics Detectors USB 4 Gas Monitor\"\u003eForensics Detectors USB 4 Gas Monitor\u003c\/a\u003e below before you order.\u003c\/div\u003e\n\n\u003ch2 id=\"top\"\u003eForensics Detectors 4 Gas Meter — Confined-Space O2, CO, H2S \u0026amp; LEL Monitor\u003c\/h2\u003e\n\n\u003cp\u003eThe \u003cstrong\u003eForensics Detectors 4 gas meter\u003c\/strong\u003e 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 \u003ca href=\"\/collections\/portable-gas-detectors\" title=\"portable gas detector\"\u003eportable gas detector\u003c\/a\u003e 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.\u003c\/p\u003e\n\n\u003cp style=\"font-size:0.9em;color:#bdae9d;margin:10px 0 18px 0;\"\u003eJump to: \u003ca href=\"#features\" style=\"color:#ffb74d;\"\u003eFeatures\u003c\/a\u003e · \u003ca href=\"#specs\" style=\"color:#ffb74d;\"\u003eSpecs\u003c\/a\u003e · \u003ca href=\"#compatibility\" style=\"color:#ffb74d;\"\u003eWhat it detects\u003c\/a\u003e · \u003ca href=\"#comparison\" style=\"color:#ffb74d;\"\u003eComparison\u003c\/a\u003e · \u003ca href=\"#faq\" style=\"color:#ffb74d;\"\u003eFAQ\u003c\/a\u003e\u003c\/p\u003e\n\n\u003cp\u003eThe Forensics Detectors 4 Gas Meter is a battery-powered, electrochemical four-gas monitor (O2, CO, H2S, LEL) with a NIST calibration certificate, designed for \u003ca href=\"\/collections\/portable-gas-detectors\" title=\"portable\"\u003eportable\u003c\/a\u003e confined-space pre-entry testing.\u003c\/p\u003e\n\n\u003ch3 id=\"features\"\u003eKey features\u003c\/h3\u003e\n\n\u003cul\u003e\n\u003cli\u003eReads all four confined-space hazards — oxygen (O2), combustible gas (LEL), carbon monoxide (CO) and hydrogen sulfide (H2S) — on one screen\u003c\/li\u003e\n\u003cli\u003eShips with a USA NIST calibration certificate so you can document instrument accuracy from day one\u003c\/li\u003e\n\u003cli\u003eTriple alarm — adjustable audible, visual LED and vibration — for noisy or low-visibility work\u003c\/li\u003e\n\u003cli\u003eElectrochemical nano sensors with zero and span calibration options for ongoing accuracy\u003c\/li\u003e\n\u003cli\u003eRugged anti-slip ABS housing that is water-resistant, dust-proof and explosion-resistant\u003c\/li\u003e\n\u003cli\u003eLight 4.8 oz body that clips to a belt or harness for pre-entry checks\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cdiv style=\"display:flex;gap:14px;flex-wrap:wrap;margin:18px 0;\"\u003e\n\u003cdiv style=\"flex:1;min-width:240px;background:#1b3a2a;border:1px solid #4caf50;border-radius:6px;padding:14px 18px;\"\u003e\n\u003cstrong style=\"color:#81c784;\"\u003ePros\u003c\/strong\u003e\u003cul style=\"margin:8px 0 0 0;\"\u003e\n\u003cli\u003eNIST calibration certificate included\u003c\/li\u003e\n\u003cli\u003eHighest customer rating in our portable lineup (4.9\/5)\u003c\/li\u003e\n\u003cli\u003eAdjustable audible, visual and vibration alarms\u003c\/li\u003e\n\u003cli\u003eVery light at 4.8 oz\u003c\/li\u003e\n\u003cli\u003eZero\/span field calibration supported\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\u003cdiv style=\"flex:1;min-width:240px;background:#3a1e1e;border:1px solid #ef5350;border-radius:6px;padding:14px 18px;\"\u003e\n\u003cstrong style=\"color:#e57373;\"\u003eCons\u003c\/strong\u003e\u003cul style=\"margin:8px 0 0 0;\"\u003e\n\u003cli\u003eDiffusion sampling only — no built-in pump for remote pre-entry testing\u003c\/li\u003e\n\u003cli\u003eField\/value-grade; not a managed-fleet instrument like Industrial Scientific or BW Honeywell\u003c\/li\u003e\n\u003cli\u003eElectrochemical sensors need periodic replacement (typically every 2–3 years)\u003c\/li\u003e\n\u003cli\u003eSingle unit — no docking-station bump\/cal automation\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\n\u003ch3 id=\"specs\"\u003eSpecifications\u003c\/h3\u003e\n\n\u003cdiv style=\"overflow-x:auto;\"\u003e\u003ctable style=\"width:100%;border-collapse:collapse;background:#1a1a1a;margin:14px 0;\"\u003e\n\u003cthead\u003e\u003ctr style=\"background:#2a2a2a;\"\u003e\n\u003cth style=\"color:#ffb74d;padding:8px 10px;border:1px solid #3a3a3a;text-align:left;\"\u003eSpecification\u003c\/th\u003e\n\u003cth style=\"color:#ffb74d;padding:8px 10px;border:1px solid #3a3a3a;text-align:left;\"\u003eDetail\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd style=\"color:#ffb74d;padding:8px 10px;border:1px solid #3a3a3a;white-space:nowrap;\"\u003eGases detected\u003c\/td\u003e\n\u003ctd style=\"color:#e0e0e0;padding:8px 10px;border:1px solid #3a3a3a;\"\u003eO2, CO, H2S, LEL combustibles\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"color:#ffb74d;padding:8px 10px;border:1px solid #3a3a3a;white-space:nowrap;\"\u003eSensor type\u003c\/td\u003e\n\u003ctd style=\"color:#e0e0e0;padding:8px 10px;border:1px solid #3a3a3a;\"\u003eElectrochemical (nano sensors)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"color:#ffb74d;padding:8px 10px;border:1px solid #3a3a3a;white-space:nowrap;\"\u003eAlarms\u003c\/td\u003e\n\u003ctd style=\"color:#e0e0e0;padding:8px 10px;border:1px solid #3a3a3a;\"\u003eAudible, visual (LED) \u0026amp; vibration, adjustable\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"color:#ffb74d;padding:8px 10px;border:1px solid #3a3a3a;white-space:nowrap;\"\u003eCalibration\u003c\/td\u003e\n\u003ctd style=\"color:#e0e0e0;padding:8px 10px;border:1px solid #3a3a3a;\"\u003eZero \u0026amp; span; NIST certificate included\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"color:#ffb74d;padding:8px 10px;border:1px solid #3a3a3a;white-space:nowrap;\"\u003ePower\u003c\/td\u003e\n\u003ctd style=\"color:#e0e0e0;padding:8px 10px;border:1px solid #3a3a3a;\"\u003eRechargeable battery\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"color:#ffb74d;padding:8px 10px;border:1px solid #3a3a3a;white-space:nowrap;\"\u003eWeight\u003c\/td\u003e\n\u003ctd style=\"color:#e0e0e0;padding:8px 10px;border:1px solid #3a3a3a;\"\u003e4.8 oz\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"color:#ffb74d;padding:8px 10px;border:1px solid #3a3a3a;white-space:nowrap;\"\u003eDimensions\u003c\/td\u003e\n\u003ctd style=\"color:#e0e0e0;padding:8px 10px;border:1px solid #3a3a3a;\"\u003e2.6\" x 1.2\" x 5.1\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"color:#ffb74d;padding:8px 10px;border:1px solid #3a3a3a;white-space:nowrap;\"\u003eBuild\u003c\/td\u003e\n\u003ctd style=\"color:#e0e0e0;padding:8px 10px;border:1px solid #3a3a3a;\"\u003eHigh-strength ABS, water\/dust\/explosion-resistant\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"color:#ffb74d;padding:8px 10px;border:1px solid #3a3a3a;white-space:nowrap;\"\u003eColor\u003c\/td\u003e\n\u003ctd style=\"color:#e0e0e0;padding:8px 10px;border:1px solid #3a3a3a;\"\u003eYellow\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\u003c\/div\u003e\n\n\u003ch3\u003eWhere the Forensics Detectors 4 Gas Meter fits\u003c\/h3\u003e\n\n\u003cul\u003e\n\u003cli\u003eConfined-space pre-entry atmosphere checks\u003c\/li\u003e\n\u003cli\u003eSewer, vault and manhole spot tests\u003c\/li\u003e\n\u003cli\u003eTank and vessel entry monitoring\u003c\/li\u003e\n\u003cli\u003eHVAC, boiler and mechanical-room checks\u003c\/li\u003e\n\u003cli\u003eGeneral industrial walk-around monitoring\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2 id=\"compatibility\"\u003eWhat the Forensics Detectors 4 Gas Meter detects (and what it doesn’t)\u003c\/h2\u003e\n\n\u003cp\u003eThis 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 \u003cstrong\u003enot\u003c\/strong\u003e 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 \u003ca href=\"\/products\/forensics-detectors-4-gas-monitor-with-pump\" title=\"Forensics Detectors 4 Gas Monitor with Pump\"\u003eForensics Detectors 4 Gas Monitor with Pump\u003c\/a\u003e 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 \u003ca href=\"\/collections\/personal-gas-detectors\" title=\"Personal \u0026amp; Wearable Gas Detectors\"\u003ePersonal \u0026amp; Wearable Gas Detectors\u003c\/a\u003e.\u003c\/p\u003e\n\n\u003cp\u003eCross-shopping? This unit sits in our \u003ca href=\"\/collections\/portable-gas-detectors\" title=\"Portable Gas Detectors\"\u003ePortable Gas Detectors\u003c\/a\u003e hub alongside the \u003ca href=\"\/products\/forensics-detectors-4-gas-monitor-usb-rechargeable\" title=\"Forensics Detectors USB 4 Gas Monitor\"\u003eForensics Detectors USB 4 Gas Monitor\u003c\/a\u003e, \u003ca href=\"\/products\/toptes-guard-863pro-4-gas-monitor\" title=\"TopTes Guard-863Pro\"\u003eTopTes Guard-863Pro\u003c\/a\u003e, \u003ca href=\"\/products\/toptes-guard-101-4-gas-detector\" title=\"TopTes Guard-101\"\u003eTopTes Guard-101\u003c\/a\u003e, \u003ca href=\"\/products\/toptes-guard-156-4-gas-monitor\" title=\"TopTes Guard-156\"\u003eTopTes Guard-156\u003c\/a\u003e. If one worker needs all-shift wear instead of a carried meter, see \u003ca href=\"\/collections\/personal-gas-detectors\" title=\"Personal \u0026amp; Wearable Gas Detectors\"\u003ePersonal \u0026amp; Wearable Gas Detectors\u003c\/a\u003e; for a fixed install or a job-site perimeter, see \u003ca href=\"\/collections\/fixed-gas-detection-systems\" title=\"Fixed Gas Detection Systems\"\u003eFixed Gas Detection Systems\u003c\/a\u003e and \u003ca href=\"\/collections\/area-gas-monitors\" title=\"Area \u0026amp; Transportable Gas Monitors\"\u003eArea \u0026amp; Transportable Gas Monitors\u003c\/a\u003e.\u003c\/p\u003e\n\n\u003ch2 id=\"comparison\"\u003eForensics Detectors 4-gas family compared\u003c\/h2\u003e\n\n\u003cdiv style=\"overflow-x:auto;\"\u003e\u003ctable style=\"width:100%;border-collapse:collapse;background:#1a1a1a;margin:14px 0;\"\u003e\n\u003ccaption style=\"color:#bdae9d;font-size:0.85em;text-align:left;padding:4px 0;\"\u003eForensics Detectors portable 4-gas family (O2, CO, H2S, LEL)\u003c\/caption\u003e\n\u003cthead\u003e\u003ctr style=\"background:#2a2a2a;\"\u003e\n\u003cth style=\"color:#ffb74d;padding:9px;border:1px solid #3a3a3a;text-align:left;\"\u003eModel\u003c\/th\u003e\n\u003cth style=\"color:#ffb74d;padding:9px;border:1px solid #3a3a3a;text-align:left;\"\u003eSampling\u003c\/th\u003e\n\u003cth style=\"color:#ffb74d;padding:9px;border:1px solid #3a3a3a;text-align:left;\"\u003eNIST cert\u003c\/th\u003e\n\u003cth style=\"color:#ffb74d;padding:9px;border:1px solid #3a3a3a;text-align:left;\"\u003eRecharge\u003c\/th\u003e\n\u003cth style=\"color:#ffb74d;padding:9px;border:1px solid #3a3a3a;text-align:left;\"\u003eStreet price\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd style=\"color:#e0e0e0;padding:9px;border:1px solid #3a3a3a;\"\u003e\u003ca href=\"\/products\/forensics-detectors-4-gas-meter-confined-space\" title=\"4 Gas Meter (Confined Space)\"\u003e4 Gas Meter (Confined Space)\u003c\/a\u003e\u003c\/td\u003e\n\u003ctd style=\"color:#e0e0e0;padding:9px;border:1px solid #3a3a3a;\"\u003eDiffusion\u003c\/td\u003e\n\u003ctd style=\"color:#e0e0e0;padding:9px;border:1px solid #3a3a3a;\"\u003eYes\u003c\/td\u003e\n\u003ctd style=\"color:#e0e0e0;padding:9px;border:1px solid #3a3a3a;\"\u003eBattery\u003c\/td\u003e\n\u003ctd style=\"color:#e0e0e0;padding:9px;border:1px solid #3a3a3a;\"\u003e~$199\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"color:#e0e0e0;padding:9px;border:1px solid #3a3a3a;\"\u003e\u003ca href=\"\/products\/forensics-detectors-4-gas-monitor-usb-rechargeable\" title=\"4 Gas Monitor (USB)\"\u003e4 Gas Monitor (USB)\u003c\/a\u003e\u003c\/td\u003e\n\u003ctd style=\"color:#e0e0e0;padding:9px;border:1px solid #3a3a3a;\"\u003eDiffusion\u003c\/td\u003e\n\u003ctd style=\"color:#e0e0e0;padding:9px;border:1px solid #3a3a3a;\"\u003eYes\u003c\/td\u003e\n\u003ctd style=\"color:#e0e0e0;padding:9px;border:1px solid #3a3a3a;\"\u003eUSB rechargeable\u003c\/td\u003e\n\u003ctd style=\"color:#e0e0e0;padding:9px;border:1px solid #3a3a3a;\"\u003e~$225\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background:#2a2520;\"\u003e\n\u003ctd style=\"color:#e0e0e0;padding:9px;border:1px solid #3a3a3a;\"\u003e\u003cstrong\u003e\u003ca href=\"\/products\/forensics-detectors-4-gas-monitor-with-pump\" title=\"4 Gas Monitor + Pump\"\u003e4 Gas Monitor + Pump\u003c\/a\u003e\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"color:#e0e0e0;padding:9px;border:1px solid #3a3a3a;\"\u003eMotorized pump + probe\u003c\/td\u003e\n\u003ctd style=\"color:#e0e0e0;padding:9px;border:1px solid #3a3a3a;\"\u003eYes\u003c\/td\u003e\n\u003ctd style=\"color:#e0e0e0;padding:9px;border:1px solid #3a3a3a;\"\u003eUSB rechargeable\u003c\/td\u003e\n\u003ctd style=\"color:#e0e0e0;padding:9px;border:1px solid #3a3a3a;\"\u003e~$299\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\u003c\/div\u003e\n\n\u003cul\u003e\n\u003cli\u003eChoose this \u003cstrong\u003e4 Gas Meter\u003c\/strong\u003e for the lightest, lowest-cost NIST-certified diffusion unit for routine pre-entry checks.\u003c\/li\u003e\n\u003cli\u003eStep up to the \u003ca href=\"\/products\/forensics-detectors-4-gas-monitor-usb-rechargeable\" title=\"USB-rechargeable 4 Gas Monitor\"\u003eUSB-rechargeable 4 Gas Monitor\u003c\/a\u003e if you want USB charging and a higher review count.\u003c\/li\u003e\n\u003cli\u003eMove to the \u003ca href=\"\/products\/forensics-detectors-4-gas-monitor-with-pump\" title=\"4 Gas Monitor with Pump\"\u003e4 Gas Monitor with Pump\u003c\/a\u003e if you must sample remotely before entry.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2 id=\"faq\"\u003eFrequently asked questions\u003c\/h2\u003e\n\n\u003ch3\u003eWhat gases does the Forensics Detectors 4 gas meter detect?\u003c\/h3\u003e\u003cp\u003eIt 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 \u003ca href=\"\/collections\/portable-gas-detectors\" title=\"Portable Gas Detectors\"\u003ePortable Gas Detectors\u003c\/a\u003e range for options.\u003c\/p\u003e\n\u003ch3\u003eIs the Forensics Detectors 4 gas meter NIST calibrated?\u003c\/h3\u003e\u003cp\u003eYes — it ships with a USA NIST calibration certificate documenting instrument accuracy at the time of calibration. You should still bump-test before each use.\u003c\/p\u003e\n\u003ch3\u003eHow do I calibrate and bump-test this meter?\u003c\/h3\u003e\u003cp\u003eUse 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.\u003c\/p\u003e\n\u003ch3\u003eCan I use this for confined-space entry?\u003c\/h3\u003e\u003cp\u003eYes — 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 \u003ca href=\"\/products\/forensics-detectors-4-gas-monitor-with-pump\" title=\"pump version\"\u003epump version\u003c\/a\u003e lets you test before anyone enters.\u003c\/p\u003e\n\u003ch3\u003eDoes it have a pump or is it diffusion?\u003c\/h3\u003e\u003cp\u003eThis model is diffusion — it reads the air around it. If you need to draw a remote sample through a probe, choose the \u003ca href=\"\/products\/forensics-detectors-4-gas-monitor-with-pump\" title=\"Forensics Detectors 4 Gas Monitor with Pump\"\u003eForensics Detectors 4 Gas Monitor with Pump\u003c\/a\u003e.\u003c\/p\u003e\n\u003ch3\u003eHow is it powered and how long does it run?\u003c\/h3\u003e\u003cp\u003eIt runs on a rechargeable internal battery sized for a full work shift. Recharge between shifts so it is always ready for pre-entry checks.\u003c\/p\u003e\n\u003ch3\u003eWhat alarms does it have?\u003c\/h3\u003e\u003cp\u003eAdjustable audible, visual LED and vibration alarms trip when a gas reaches its preset level — useful in loud or low-visibility environments.\u003c\/p\u003e\n\u003ch3\u003eHow long do the sensors last?\u003c\/h3\u003e\u003cp\u003eThe electrochemical sensors typically last two to three years depending on exposure. Budget for sensor replacement and calibration gas as ongoing costs.\u003c\/p\u003e\n\u003ch3\u003eWhat does this meter NOT detect?\u003c\/h3\u003e\u003cp\u003eIt 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 \u003ca href=\"\/collections\/portable-gas-detectors\" title=\"Portable Gas Detectors\"\u003ePortable Gas Detectors\u003c\/a\u003e hub.\u003c\/p\u003e\n\u003ch3\u003eIs it in stock and how does it ship?\u003c\/h3\u003e\u003cp\u003eStocked items ship through our Amazon fulfillment partner; use the buy button for current availability and delivery timing.\u003c\/p\u003e\n\u003ch3\u003eHow does it compare to the USB-rechargeable Forensics monitor?\u003c\/h3\u003e\u003cp\u003eBoth read the same four gases with NIST certificates; the \u003ca href=\"\/products\/forensics-detectors-4-gas-monitor-usb-rechargeable\" title=\"USB 4 Gas Monitor\"\u003eUSB 4 Gas Monitor\u003c\/a\u003e adds USB charging and has more reviews, while this meter is lighter and lower cost.\u003c\/p\u003e\n\u003ch3\u003eIs this an industrial-grade instrument?\u003c\/h3\u003e\u003cp\u003eIt 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.\u003c\/p\u003e\n\n\u003cdiv style=\"background:#1a1a1a;border:1px solid #3a3a3a;border-radius:6px;padding:16px 18px;margin:22px 0;\"\u003e\n\u003cp style=\"margin:0 0 10px 0;color:#f5e6d3;\"\u003eReady to order the \u003cstrong\u003eForensics Detectors 4 gas meter\u003c\/strong\u003e? Add it to your cart above, or check the current Amazon price below. Compare it against the rest of our \u003ca href=\"\/collections\/portable-gas-detectors\" title=\"Portable Gas Detectors\"\u003ePortable Gas Detectors\u003c\/a\u003e lineup before you buy.\u003c\/p\u003e\n\u003cp style=\"display:flex;gap:10px;flex-wrap:wrap;align-items:center;margin:0;\"\u003e\u003ca href=\"https:\/\/www.amazon.com\/dp\/B0GNQ37S9C?tag=wcsafety04-20\" rel=\"sponsored nofollow noopener\" target=\"_blank\" style=\"display:inline-block;background:#FFD814;color:#0F1111;padding:13px 26px;text-decoration:none;font-weight:bold;border-radius:4px;border:1px solid #FCD200;\"\u003eCHECK PRICE ON AMAZON →\u003c\/a\u003e\u003cspan style=\"font-size:0.8em;color:#bdae9d;\"\u003eAs an Amazon Associate, WC Safety earns from qualifying purchases.\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/div\u003e\n\n\u003cdiv style=\"background:#1a2733;border:1px dashed #4fc3f7;padding:16px 20px;margin:30px 0 18px 0;color:#cfd8dc;font-size:0.92em;\"\u003e\n  \u003cstrong style=\"color:#4fc3f7;\"\u003eWhy trust this Forensics Detectors page?\u003c\/strong\u003e WC Safety is an independent industrial safety-equipment retailer serving safety managers, procurement teams and field supervisors. The specifications on this page are taken from the manufacturer’s published listing for Forensics Detectors 4 Gas Meter and framed against \u003ca href=\"https:\/\/www.osha.gov\/laws-regs\/regulations\/standardnumber\/1910\/1910.146\" rel=\"noopener\" target=\"_blank\" style=\"color:#4fc3f7;\"\u003eOSHA 29 CFR 1910.146\u003c\/a\u003e for confined-space atmospheric testing. Disclosed: WC Safety earns Amazon affiliate commissions on outbound clicks; that does not influence the specs shown or where this unit sits in our lineup.\n\u003c\/div\u003e\n\u003cdiv style=\"background:#1a2733;border-left:4px solid #4fc3f7;padding:18px 22px;margin:18px 0;color:#cfd8dc;font-size:0.92em;\"\u003e\n  \u003cstrong style=\"color:#4fc3f7;\"\u003eBy Steven Eaton, WC Safety Editorial\u003c\/strong\u003e — Industrial safety-equipment desk · specialization: portable atmospheric monitoring, confined-space gas detection and instrument selection.\u003cbr\u003e\n  \u003cstrong\u003eLast updated:\u003c\/strong\u003e \u003ctime datetime=\"2026-06-22\"\u003eJune 22, 2026\u003c\/time\u003e · \u003cstrong\u003eSources reviewed:\u003c\/strong\u003e manufacturer product listing \u0026amp; specifications, OSHA 29 CFR 1910.146, OSHA Annotated PEL tables, ACGIH Threshold Limit Values.\u003cbr\u003e\n  \u003cstrong\u003eEditorial standard:\u003c\/strong\u003e \u003cem\u003eZero sponsored listings. No manufacturer input. Specs verified against the manufacturer’s published data.\u003c\/em\u003e\n\u003c\/div\u003e\n\u003cdiv style=\"background:#1a2733;border-left:4px solid #4fc3f7;padding:16px 20px;margin:18px 0;color:#cfd8dc;font-size:0.92em;\"\u003e\n  \u003cstrong style=\"color:#4fc3f7;\"\u003eHow this page is maintained.\u003c\/strong\u003e Specifications and pricing are reviewed against the manufacturer’s current listing and re-checked whenever the lineup changes. Gas-detection guidance follows \u003ca href=\"https:\/\/www.osha.gov\/laws-regs\/regulations\/standardnumber\/1910\/1910.146\" rel=\"noopener\" target=\"_blank\" style=\"color:#4fc3f7;\"\u003eOSHA 1910.146\u003c\/a\u003e (permit-required confined spaces) and \u003ca href=\"https:\/\/www.osha.gov\/annotated-pels\" rel=\"noopener\" target=\"_blank\" style=\"color:#4fc3f7;\"\u003eOSHA Permissible Exposure Limits\u003c\/a\u003e, cross-referenced with ACGIH TLVs.\n\u003c\/div\u003e\n\u003cdiv style=\"background:#2a2520;border-left:4px solid #ff9800;padding:16px 20px;margin:18px 0;color:#f5e6d3;font-size:0.92em;\"\u003e\n  \u003cstrong style=\"color:#ffb74d;\"\u003eDisclosure.\u003c\/strong\u003e WC Safety participates in the Amazon Associates Program and earns commissions on qualifying purchases through outbound links on this page (tag wcsafety04-20). We are not sponsored by any instrument manufacturer. This page is buyer guidance, not medical, legal or regulatory advice — confirm gas-detection requirements for your site against the applicable OSHA standard and, for commercial monitoring programs, a Certified Industrial Hygienist (CIH).\n\u003c\/div\u003e\n\n\u003cscript type=\"application\/ld+json\"\u003e\n{\"@context\": \"https:\/\/schema.org\", \"@graph\": [{\"@type\": \"Product\", \"@id\": \"https:\/\/wcsafety.com\/products\/forensics-detectors-4-gas-meter-confined-space#product\", \"name\": \"Forensics Detectors 4 Gas Meter for Confined Space (O2, CO, H2S, LEL)\", \"description\": \"Forensics Detectors 4 gas meter for confined space — O2, CO, H2S \u0026 LEL, NIST-calibrated with triple alarm. Order this pre-entry monitor at WC Safety.\", \"sku\": \"B0GNQ37S9C\", \"mpn\": \"FD-4Gas\", \"image\": [\"https:\/\/wcsafety.com\/cdn\/shop\/products\/forensics-detectors-4-gas-meter-confined-space.jpg\"], \"brand\": {\"@type\": \"Brand\", \"name\": \"Forensics Detectors\"}, \"category\": \"Portable Gas Detector\", \"isPartOf\": {\"@type\": \"CollectionPage\", \"@id\": \"https:\/\/wcsafety.com\/collections\/portable-gas-detectors#collection\", \"name\": \"Portable Gas Detectors\", \"url\": \"https:\/\/wcsafety.com\/collections\/portable-gas-detectors\"}, \"isRelatedTo\": [{\"@type\": \"Product\", \"name\": \"Forensics Detectors 4 Gas Monitor (USB Rechargeable)\", \"url\": \"https:\/\/wcsafety.com\/products\/forensics-detectors-4-gas-monitor-usb-rechargeable\"}, {\"@type\": \"Product\", \"name\": \"TopTes Guard-863Pro 4 Gas Monitor\", \"url\": \"https:\/\/wcsafety.com\/products\/toptes-guard-863pro-4-gas-monitor\"}, {\"@type\": \"Product\", \"name\": \"TopTes Guard-101 4 Gas Detector\", \"url\": \"https:\/\/wcsafety.com\/products\/toptes-guard-101-4-gas-detector\"}, {\"@type\": \"Product\", \"name\": \"TopTes Guard-156 4 Gas Monitor\", \"url\": \"https:\/\/wcsafety.com\/products\/toptes-guard-156-4-gas-monitor\"}, {\"@type\": \"Product\", \"name\": \"Forensics Detectors 4 Gas Monitor with Pump\", \"url\": \"https:\/\/wcsafety.com\/products\/forensics-detectors-4-gas-monitor-with-pump\"}, {\"@type\": \"Product\", \"name\": \"Forsensal 4 Gas Detector with Pump\", \"url\": \"https:\/\/wcsafety.com\/products\/forsensal-4-gas-detector-with-pump\"}], \"offers\": {\"@type\": \"Offer\", \"url\": \"https:\/\/wcsafety.com\/products\/forensics-detectors-4-gas-meter-confined-space\", \"priceCurrency\": \"USD\", \"price\": \"199.00\", \"availability\": \"https:\/\/schema.org\/InStock\", \"seller\": {\"@type\": \"Organization\", \"name\": \"WC Safety\"}}}, {\"@type\": \"BreadcrumbList\", \"@id\": \"https:\/\/wcsafety.com\/products\/forensics-detectors-4-gas-meter-confined-space#breadcrumb\", \"itemListElement\": [{\"@type\": \"ListItem\", \"position\": 1, \"name\": \"Home\", \"item\": \"https:\/\/wcsafety.com\/\"}, {\"@type\": \"ListItem\", \"position\": 2, \"name\": \"Gas Detectors\", \"item\": \"https:\/\/wcsafety.com\/collections\/gas-detectors\"}, {\"@type\": \"ListItem\", \"position\": 3, \"name\": \"Portable Gas Detectors\", \"item\": \"https:\/\/wcsafety.com\/collections\/portable-gas-detectors\"}, {\"@type\": \"ListItem\", \"position\": 4, \"name\": \"Forensics Detectors 4 Gas Meter for Confined Space (O2, CO, H2S, LEL)\"}]}, {\"@type\": \"FAQPage\", \"mainEntity\": [{\"@type\": \"Question\", \"name\": \"What gases does the Forensics Detectors 4 gas meter detect?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"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.\"}}, {\"@type\": \"Question\", \"name\": \"Is the Forensics Detectors 4 gas meter NIST calibrated?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"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.\"}}, {\"@type\": \"Question\", \"name\": \"How do I calibrate and bump-test this meter?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"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.\"}}, {\"@type\": \"Question\", \"name\": \"Can I use this for confined-space entry?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"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.\"}}, {\"@type\": \"Question\", \"name\": \"Does it have a pump or is it diffusion?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"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.\"}}, {\"@type\": \"Question\", \"name\": \"How is it powered and how long does it run?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"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.\"}}, {\"@type\": \"Question\", \"name\": \"What alarms does it have?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Adjustable audible, visual LED and vibration alarms trip when a gas reaches its preset level — useful in loud or low-visibility environments.\"}}, {\"@type\": \"Question\", \"name\": \"How long do the sensors last?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"The electrochemical sensors typically last two to three years depending on exposure. Budget for sensor replacement and calibration gas as ongoing costs.\"}}, {\"@type\": \"Question\", \"name\": \"What does this meter NOT detect?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"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.\"}}, {\"@type\": \"Question\", \"name\": \"Is it in stock and how does it ship?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Stocked items ship through our Amazon fulfillment partner; use the buy button for current availability and delivery timing.\"}}, {\"@type\": \"Question\", \"name\": \"How does it compare to the USB-rechargeable Forensics monitor?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"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.\"}}, {\"@type\": \"Question\", \"name\": \"Is this an industrial-grade instrument?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"It is a NIST-certified field meter well suited to small crews and facilities. 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