{"product_id":"forensics-4-gas-wall-mount-monitor","title":"Forensics 4 Gas Wall-Mount Monitor — CO, H2S, O2 \u0026 LEL (Relay Output)","description":"\u003c!-- PRODUCT B0C19GM4XC | tag fixed-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 4 gas wall-mount monitor is one of the instruments we curate in our \u003ca href=\"\/collections\/fixed-gas-detection-systems\" title=\"Fixed Gas Detection Systems\"\u003eFixed Gas Detection Systems\u003c\/a\u003e buyer’s hub. Compare it with the \u003ca href=\"\/products\/forensics-ex-lel-gas-detector-wall-mount\" title=\"Forensics EX\/LEL Wall-Mount\"\u003eForensics EX\/LEL Wall-Mount\u003c\/a\u003e below before you order.\u003c\/div\u003e\n\n\u003ch2 id=\"top\"\u003eForensics 4 Gas Wall-Mount Monitor — Fixed CO, H2S, O2 \u0026amp; LEL\u003c\/h2\u003e\n\n\u003cp\u003eThe \u003cstrong\u003eForensics 4 gas wall-mount monitor\u003c\/strong\u003e reads CO, H2S, O2 and combustible LEL from a single fixed head — a \u003ca href=\"\/collections\/fixed-gas-detection-systems\" title=\"fixed gas detection system\"\u003efixed gas detection system\u003c\/a\u003e that covers all four atmospheric hazards continuously and drives ventilation or shutdown through its relay output.\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 4 Gas Wall-Mount Monitor is a fixed, continuously-monitoring detector for CO, H2S, O2 and combustible LEL, with relay output and NIST-traceable calibration.\u003c\/p\u003e\n\n\u003ch3 id=\"features\"\u003eKey features\u003c\/h3\u003e\n\n\u003cul\u003e\n\u003cli\u003eMonitors all four atmospheric hazards — CO, H2S, O2 and combustible LEL — from one fixed head\u003c\/li\u003e\n\u003cli\u003eContinuous wall-mounted coverage of an unattended space\u003c\/li\u003e\n\u003cli\u003eRelay output drives ventilation, alarms or shutdown\u003c\/li\u003e\n\u003cli\u003eAdjustable audible and visual alarms per gas\u003c\/li\u003e\n\u003cli\u003eUSA NIST-traceable calibration\u003c\/li\u003e\n\u003cli\u003eThe all-in-one fixed solution where several gases are a risk\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\u003eFour gases from one fixed head\u003c\/li\u003e\n\u003cli\u003eContinuous unattended monitoring\u003c\/li\u003e\n\u003cli\u003eRelay output for ventilation\/shutdown\u003c\/li\u003e\n\u003cli\u003eNIST-traceable calibration\u003c\/li\u003e\n\u003cli\u003eSimplifies multi-gas install\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\u003eHighest cost in the Forensics fixed family\u003c\/li\u003e\n\u003cli\u003eSingle point coverage\u003c\/li\u003e\n\u003cli\u003eHard-wired install required\u003c\/li\u003e\n\u003cli\u003eNot portable\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;\"\u003eCO, H2S, O2, EX (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;\"\u003eMounting\u003c\/td\u003e\n\u003ctd style=\"color:#e0e0e0;padding:8px 10px;border:1px solid #3a3a3a;\"\u003eWall-mount, fixed\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;\"\u003eMonitoring\u003c\/td\u003e\n\u003ctd style=\"color:#e0e0e0;padding:8px 10px;border:1px solid #3a3a3a;\"\u003eContinuous (always on)\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;\"\u003eOutput\u003c\/td\u003e\n\u003ctd style=\"color:#e0e0e0;padding:8px 10px;border:1px solid #3a3a3a;\"\u003eRelay output + adjustable sound \u0026amp; light alarms\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;\"\u003eUSA NIST-traceable\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;\"\u003eEnclosure\u003c\/td\u003e\n\u003ctd style=\"color:#e0e0e0;padding:8px 10px;border:1px solid #3a3a3a;\"\u003eIndustrial\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;\"\u003e3 lb\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\u003c\/div\u003e\n\n\u003ch3\u003eWhere the Forensics 4 Gas Wall-Mount Monitor fits\u003c\/h3\u003e\n\n\u003cul\u003e\n\u003cli\u003eWastewater and pump stations\u003c\/li\u003e\n\u003cli\u003eConfined or below-grade plant rooms\u003c\/li\u003e\n\u003cli\u003eParking and loading areas (CO)\u003c\/li\u003e\n\u003cli\u003eDigesters and tanks (H2S, O2)\u003c\/li\u003e\n\u003cli\u003eAny space with multiple gas hazards\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2 id=\"compatibility\"\u003eWhat the Forensics 4 Gas Wall-Mount Monitor detects (and what it doesn’t)\u003c\/h2\u003e\n\n\u003cp\u003eThis monitor covers \u003cstrong\u003eCO, H2S, O2 and combustible LEL\u003c\/strong\u003e — the four atmospheric hazards — but not VOCs, CO2 or specific toxics like chlorine. For a single combustible point use the \u003ca href=\"\/products\/forensics-ex-lel-gas-detector-wall-mount\" title=\"Forensics EX LEL Detector\"\u003eForensics EX LEL Detector\u003c\/a\u003e; for hydrogen the \u003ca href=\"\/products\/forensics-hydrogen-gas-detector-wall-mount\" title=\"Hydrogen Detector\"\u003eHydrogen Detector\u003c\/a\u003e. Mount it considering each gas’s density and the room layout, and tie the relay into ventilation or shutdown. It protects the installed space; entrants still need a \u003ca href=\"\/collections\/portable-gas-detectors\" title=\"Portable Gas Detectors\"\u003ePortable Gas Detectors\u003c\/a\u003e instrument for pre-entry testing and a \u003ca href=\"\/collections\/personal-gas-detectors\" title=\"Personal \u0026amp; Wearable Gas Detectors\"\u003ePersonal \u0026amp; Wearable Gas Detectors\u003c\/a\u003e clip during work.\u003c\/p\u003e\n\n\u003cp\u003eCross-shopping? This unit sits in our \u003ca href=\"\/collections\/fixed-gas-detection-systems\" title=\"Fixed Gas Detection Systems\"\u003eFixed Gas Detection Systems\u003c\/a\u003e hub alongside \u003ca href=\"\/products\/forensics-ex-lel-gas-detector-wall-mount\" title=\"Forensics EX\/LEL Wall-Mount\"\u003eForensics EX\/LEL Wall-Mount\u003c\/a\u003e, \u003ca href=\"\/products\/forensics-hydrogen-gas-detector-wall-mount\" title=\"Forensics Hydrogen Wall-Mount\"\u003eForensics Hydrogen Wall-Mount\u003c\/a\u003e, \u003ca href=\"\/products\/macurco-pm100-co-fixed-carbon-monoxide-monitor\" title=\"Macurco PM100-CO\"\u003eMacurco PM100-CO\u003c\/a\u003e, \u003ca href=\"\/products\/macurco-gbc-24-2-gas-detection-controller\" title=\"Macurco GBC-24-2\"\u003eMacurco GBC-24-2\u003c\/a\u003e. For other gas-detection form factors see \u003ca href=\"\/collections\/portable-gas-detectors\" title=\"Portable Gas Detectors\"\u003ePortable Gas Detectors\u003c\/a\u003e, \u003ca href=\"\/collections\/personal-gas-detectors\" title=\"Personal \u0026amp; Wearable Gas Detectors\"\u003ePersonal \u0026amp; Wearable Gas Detectors\u003c\/a\u003e, \u003ca href=\"\/collections\/area-gas-monitors\" title=\"Area \u0026amp; Transportable Gas Monitors\"\u003eArea \u0026amp; Transportable Gas Monitors\u003c\/a\u003e, or browse the full \u003ca href=\"\/collections\/gas-detectors\" title=\"Gas Detectors\"\u003eGas Detectors\u003c\/a\u003e range.\u003c\/p\u003e\n\n\u003ch2 id=\"comparison\"\u003eForensics fixed wall-mount 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 fixed wall-mount family (continuous monitoring, relay output, NIST-traceable)\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;\"\u003eGas(es)\u003c\/th\u003e\n\u003cth style=\"color:#ffb74d;padding:9px;border:1px solid #3a3a3a;text-align:left;\"\u003eRange\u003c\/th\u003e\n\u003cth style=\"color:#ffb74d;padding:9px;border:1px solid #3a3a3a;text-align:left;\"\u003eOutput\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-ex-lel-gas-detector-wall-mount\" title=\"EX LEL Detector\"\u003eEX LEL Detector\u003c\/a\u003e\u003c\/td\u003e\n\u003ctd style=\"color:#e0e0e0;padding:9px;border:1px solid #3a3a3a;\"\u003eCombustibles (EX)\u003c\/td\u003e\n\u003ctd style=\"color:#e0e0e0;padding:9px;border:1px solid #3a3a3a;\"\u003e0-100% LEL\u003c\/td\u003e\n\u003ctd style=\"color:#e0e0e0;padding:9px;border:1px solid #3a3a3a;\"\u003eRelay + alarms\u003c\/td\u003e\n\u003ctd style=\"color:#e0e0e0;padding:9px;border:1px solid #3a3a3a;\"\u003e~$599\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-hydrogen-gas-detector-wall-mount\" title=\"Hydrogen Detector\"\u003eHydrogen Detector\u003c\/a\u003e\u003c\/td\u003e\n\u003ctd style=\"color:#e0e0e0;padding:9px;border:1px solid #3a3a3a;\"\u003eHydrogen (H2)\u003c\/td\u003e\n\u003ctd style=\"color:#e0e0e0;padding:9px;border:1px solid #3a3a3a;\"\u003e0-1000 ppm\u003c\/td\u003e\n\u003ctd style=\"color:#e0e0e0;padding:9px;border:1px solid #3a3a3a;\"\u003eRelay + alarms\u003c\/td\u003e\n\u003ctd style=\"color:#e0e0e0;padding:9px;border:1px solid #3a3a3a;\"\u003e~$799\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-4-gas-wall-mount-monitor\" title=\"4 Gas Monitor\"\u003e4 Gas Monitor\u003c\/a\u003e\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"color:#e0e0e0;padding:9px;border:1px solid #3a3a3a;\"\u003eCO, H2S, O2, EX LEL\u003c\/td\u003e\n\u003ctd style=\"color:#e0e0e0;padding:9px;border:1px solid #3a3a3a;\"\u003eMulti-gas\u003c\/td\u003e\n\u003ctd style=\"color:#e0e0e0;padding:9px;border:1px solid #3a3a3a;\"\u003eRelay + alarms\u003c\/td\u003e\n\u003ctd style=\"color:#e0e0e0;padding:9px;border:1px solid #3a3a3a;\"\u003e~$1,395\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 the \u003cstrong\u003e4 Gas Wall-Mount Monitor\u003c\/strong\u003e when a space has several gas hazards and you want one fixed head.\u003c\/li\u003e\n\u003cli\u003eFor combustibles only, the \u003ca href=\"\/products\/forensics-ex-lel-gas-detector-wall-mount\" title=\"EX LEL Detector\"\u003eEX LEL Detector\u003c\/a\u003e costs less.\u003c\/li\u003e\n\u003cli\u003eFor battery-room hydrogen, use the \u003ca href=\"\/products\/forensics-hydrogen-gas-detector-wall-mount\" title=\"Hydrogen Detector\"\u003eHydrogen Detector\u003c\/a\u003e.\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 4 gas wall-mount monitor detect?\u003c\/h3\u003e\u003cp\u003eCO, H2S, O2 and combustible LEL — the four atmospheric hazards — continuously, from one fixed head. It does not detect VOCs or specific toxics like chlorine.\u003c\/p\u003e\n\u003ch3\u003eWhy choose a fixed 4-gas monitor over single-gas heads?\u003c\/h3\u003e\u003cp\u003eOne unit covers all four hazards, simplifying installation and wiring where several gases are a risk. For a single hazard, a dedicated head like the \u003ca href=\"\/products\/forensics-ex-lel-gas-detector-wall-mount\" title=\"EX LEL Detector\"\u003eEX LEL Detector\u003c\/a\u003e costs less.\u003c\/p\u003e\n\u003ch3\u003eWhat is the relay output used for?\u003c\/h3\u003e\u003cp\u003eIt triggers external action — ventilation, remote alarms or equipment shutdown — when any monitored gas reaches its set point.\u003c\/p\u003e\n\u003ch3\u003eWhere should it be mounted?\u003c\/h3\u003e\u003cp\u003ePosition it considering each gas's density and the room's release points and occupied zones; below-grade and enclosed plant rooms are common applications.\u003c\/p\u003e\n\u003ch3\u003eIs it NIST calibrated?\u003c\/h3\u003e\u003cp\u003eYes — USA NIST-traceable calibration; plan periodic recalibration of each sensor with the appropriate calibration gas.\u003c\/p\u003e\n\u003ch3\u003eCan it replace portable detectors for entry?\u003c\/h3\u003e\u003cp\u003eNo — pre-entry testing still needs a \u003ca href=\"\/collections\/portable-gas-detectors\" title=\"Portable Gas Detectors\"\u003ePortable Gas Detectors\u003c\/a\u003e instrument. The fixed monitor provides continuous coverage of the installed space.\u003c\/p\u003e\n\u003ch3\u003eDoes it monitor oxygen deficiency?\u003c\/h3\u003e\u003cp\u003eYes — oxygen is one of its four channels, alarming on deficiency (and typically enrichment) alongside CO, H2S and combustibles.\u003c\/p\u003e\n\u003ch3\u003eHow is it powered and installed?\u003c\/h3\u003e\u003cp\u003eIt is a hard-wired fixed monitor; installation and relay wiring should follow local electrical code and any area-classification requirements.\u003c\/p\u003e\n\u003ch3\u003eWhat does it not detect?\u003c\/h3\u003e\u003cp\u003eVOCs, CO2 and specific toxics such as chlorine or ammonia. For a single combustible point use the \u003ca href=\"\/products\/forensics-ex-lel-gas-detector-wall-mount\" title=\"EX LEL Detector\"\u003eEX LEL Detector\u003c\/a\u003e; for hydrogen the \u003ca href=\"\/products\/forensics-hydrogen-gas-detector-wall-mount\" title=\"Hydrogen Detector\"\u003eHydrogen Detector\u003c\/a\u003e.\u003c\/p\u003e\n\u003ch3\u003eIs it in stock and how does it ship?\u003c\/h3\u003e\u003cp\u003eUse the Amazon buy button for current availability and delivery timing through our fulfillment partner.\u003c\/p\u003e\n\u003ch3\u003eCan it drive building ventilation automatically?\u003c\/h3\u003e\u003cp\u003eYes — that is a core use of the relay output: energise exhaust or a shutdown circuit when gas reaches the alarm level.\u003c\/p\u003e\n\u003ch3\u003eHow many heads does a facility need?\u003c\/h3\u003e\u003cp\u003eOne per area near its release points; larger or multi-room facilities add heads positioned by airflow and gas density, often wired to a central controller.\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 4 gas wall-mount monitor\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\/fixed-gas-detection-systems\" title=\"Fixed Gas Detection Systems\"\u003eFixed Gas Detection Systems\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\/B0C19GM4XC?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 here are taken from the manufacturer’s published listing for Forensics 4 Gas Wall-Mount Monitor 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 and \u003ca href=\"https:\/\/www.osha.gov\/annotated-pels\" rel=\"noopener\" target=\"_blank\" style=\"color:#4fc3f7;\"\u003eOSHA Permissible Exposure Limits\u003c\/a\u003e. Disclosed: WC Safety earns Amazon affiliate commissions on outbound clicks; that does not influence the specs shown or 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: atmospheric monitoring, 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 and \u003ca href=\"https:\/\/www.osha.gov\/annotated-pels\" rel=\"noopener\" target=\"_blank\" style=\"color:#4fc3f7;\"\u003eOSHA PELs\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-4-gas-wall-mount-monitor#product\", \"name\": \"Forensics 4 Gas Wall-Mount Monitor — CO, H2S, O2 \u0026 LEL (Relay Output)\", \"description\": \"Forensics 4 gas wall-mount monitor — fixed CO, H2S, O2 \u0026 LEL detector, continuous monitoring with relay output and NIST-traceable calibration.\", \"sku\": \"B0C19GM4XC\", \"mpn\": \"FD-4GWM\", \"image\": [\"https:\/\/wcsafety.com\/cdn\/shop\/products\/forensics-4-gas-wall-mount-monitor.jpg\"], \"brand\": {\"@type\": \"Brand\", \"name\": \"Forensics Detectors\"}, \"category\": \"Fixed Gas Detector\", \"isPartOf\": {\"@type\": \"CollectionPage\", \"@id\": \"https:\/\/wcsafety.com\/collections\/fixed-gas-detection-systems#collection\", \"name\": \"Fixed Gas Detection Systems\", \"url\": \"https:\/\/wcsafety.com\/collections\/fixed-gas-detection-systems\"}, \"isRelatedTo\": [{\"@type\": \"Product\", \"name\": \"Forensics EX LEL Gas Detector (Wall-Mount)\", \"url\": \"https:\/\/wcsafety.com\/products\/forensics-ex-lel-gas-detector-wall-mount\"}, {\"@type\": \"Product\", \"name\": \"Forensics Hydrogen Gas Detector (Wall-Mount)\", \"url\": \"https:\/\/wcsafety.com\/products\/forensics-hydrogen-gas-detector-wall-mount\"}, {\"@type\": \"Product\", \"name\": \"Macurco PM100-CO Fixed CO Monitor\", \"url\": \"https:\/\/wcsafety.com\/products\/macurco-pm100-co-fixed-carbon-monoxide-monitor\"}, {\"@type\": \"Product\", \"name\": \"Macurco GBC-24-2 Gas Detection Controller\", \"url\": \"https:\/\/wcsafety.com\/products\/macurco-gbc-24-2-gas-detection-controller\"}], \"offers\": {\"@type\": \"Offer\", \"url\": \"https:\/\/wcsafety.com\/products\/forensics-4-gas-wall-mount-monitor\", \"priceCurrency\": \"USD\", \"price\": \"1395.00\", \"availability\": \"https:\/\/schema.org\/InStock\", \"seller\": {\"@type\": \"Organization\", \"name\": \"WC Safety\"}}}, {\"@type\": \"BreadcrumbList\", \"@id\": \"https:\/\/wcsafety.com\/products\/forensics-4-gas-wall-mount-monitor#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\": \"Fixed Gas Detection Systems\", \"item\": \"https:\/\/wcsafety.com\/collections\/fixed-gas-detection-systems\"}, {\"@type\": \"ListItem\", \"position\": 4, \"name\": \"Forensics 4 Gas Wall-Mount Monitor — CO, H2S, O2 \u0026 LEL (Relay Output)\"}]}, {\"@type\": \"FAQPage\", \"mainEntity\": [{\"@type\": \"Question\", \"name\": \"What gases does the Forensics 4 gas wall-mount monitor detect?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"CO, H2S, O2 and combustible LEL — the four atmospheric hazards — continuously, from one fixed head. It does not detect VOCs or specific toxics like chlorine.\"}}, {\"@type\": \"Question\", \"name\": \"Why choose a fixed 4-gas monitor over single-gas heads?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"One unit covers all four hazards, simplifying installation and wiring where several gases are a risk. For a single hazard, a dedicated head like the EX LEL Detector costs less.\"}}, {\"@type\": \"Question\", \"name\": \"What is the relay output used for?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"It triggers external action — ventilation, remote alarms or equipment shutdown — when any monitored gas reaches its set point.\"}}, {\"@type\": \"Question\", \"name\": \"Where should it be mounted?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Position it considering each gas's density and the room's release points and occupied zones; below-grade and enclosed plant rooms are common applications.\"}}, {\"@type\": \"Question\", \"name\": \"Is it NIST calibrated?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Yes — USA NIST-traceable calibration; plan periodic recalibration of each sensor with the appropriate calibration gas.\"}}, {\"@type\": \"Question\", \"name\": \"Can it replace portable detectors for entry?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"No — pre-entry testing still needs a Portable Gas Detectors instrument. The fixed monitor provides continuous coverage of the installed space.\"}}, {\"@type\": \"Question\", \"name\": \"Does it monitor oxygen deficiency?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Yes — oxygen is one of its four channels, alarming on deficiency (and typically enrichment) alongside CO, H2S and combustibles.\"}}, {\"@type\": \"Question\", \"name\": \"How is it powered and installed?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"It is a hard-wired fixed monitor; installation and relay wiring should follow local electrical code and any area-classification requirements.\"}}, {\"@type\": \"Question\", \"name\": \"What does it not detect?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"VOCs, CO2 and specific toxics such as chlorine or ammonia. For a single combustible point use the EX LEL Detector; for hydrogen the Hydrogen Detector.\"}}, {\"@type\": \"Question\", \"name\": \"Is it in stock and how does it ship?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Use the Amazon buy button for current availability and delivery timing through our fulfillment partner.\"}}, {\"@type\": \"Question\", \"name\": \"Can it drive building ventilation automatically?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Yes — that is a core use of the relay output: energise exhaust or a shutdown circuit when gas reaches the alarm level.\"}}, {\"@type\": \"Question\", \"name\": \"How many heads does a facility need?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"One per area near its release points; larger or multi-room facilities add heads positioned by airflow and gas density, often wired to a central controller.\"}}]}, {\"@type\": \"Organization\", \"@id\": \"https:\/\/wcsafety.com\/#org\", \"name\": \"WC Safety\", \"url\": \"https:\/\/wcsafety.com\", \"logo\": \"https:\/\/wcsafety.com\/cdn\/shop\/files\/logo.png\"}, {\"@type\": \"Person\", \"@id\": \"https:\/\/wcsafety.com\/#editor\", \"name\": \"Steven Eaton\", \"jobTitle\": \"Editorial Lead\", \"worksFor\": {\"@id\": \"https:\/\/wcsafety.com\/#org\"}, \"knowsAbout\": [\"industrial gas detection\", \"atmospheric monitoring\", \"personal protective equipment\"]}, {\"@type\": \"Brand\", \"name\": \"Forensics Detectors\"}]}\n\u003c\/script\u003e","brand":"Forensics Detectors","offers":[{"title":"Default Title","offer_id":44266497146968,"sku":"B0C19GM4XC","price":1395.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0594\/1900\/0920\/files\/71YQjzkBeeL._AC_SL1500.jpg?v=1782122849","url":"https:\/\/wcsafety.com\/products\/forensics-4-gas-wall-mount-monitor","provider":"WC Safety","version":"1.0","type":"link"}