Fixed VOC Monitor

Fixed VOC monitors are suitable for continuous online detection and alarm of volatile organic compound (VOC) gases in workshops, enclosed work areas, and around equipment. The robust and durable explosion-proof enclosure is suitable for various hazardous locations and harsh industrial environments.

VOCs, or Volatile Organic Compounds, are a class of organic compounds that readily evaporate at room temperature. They are composed of carbon (C) and hydrogen (H) elements and can originate from various chemical substances, including solvents, fuels, paints, and cleaning agents. Common examples include benzene, formaldehyde, xylene, and ethanol. Due to their volatility, they can rapidly convert to gas at room temperature and disperse into the surrounding air.

★★★★★

  • Short delivery time
  • Better price
  • Customizable parameters

Features

  • Real-time monitoring via wired or wireless remote transmission and network transmission;
  • Simultaneous output of three-wire 4-20mA standard signal and standard bus RS485 (Modbus-RTU);
  • Optional frequency output 200-1000Hz, Hart protocol signal, 1-5V output, two-wire 4-20mA, wireless transmission (2-5 km or unlimited distance);
  • Compatible with secondary instruments, data acquisition modules, PLCs, and DCS systems; capable of driving related equipment.
  • Primary detection principles include: catalytic combustion (explosion limit measurement), thermal conductivity (leak detection), and high-precision PID photoionization;
  • Automatic protection against high-concentration gas surges;
  • Reverse-connection protection design prevents instrument damage from any wiring error;
  • Freely switchable concentration display units;
  • Operational error recovery function restores settings to previous state within a defined timeframe;
  • Supports IP66 waterproof/dustproof rating, resists strong electromagnetic interference and static electricity, suitable for hazardous and harsh environments;
  • Operates normally at -40°C to +70°C with automatic temperature compensation;
  • Reverse connection protection prevents damage to the VOC online monitoring device from any wiring errors.
  • Standard infrared remote control enables remote alarm silencing, alarm threshold adjustment, and factory reset.
  • Independent gas chamber prevents particulates and impurities from entering with the sample gas, enhancing longevity and reliability.

Specifications

Measurable GasesVOCs (Parameters can be customized; other gases can also be customized, see gas appendix)
Measuring range and resolutionVOC: 0-100ppm, 0.01ppm, imported high-precision electrochemical principle sensor

or VOC: 0-100%LEL, 0.1%LEL, industrial-grade catalytic combustion principle sensor

or VOC: 0-10ppm, 0.01ppm, imported high-precision PID photoionization principle sensor

Refer to the attached table; other ranges, principles, and resolutions can be customized.
Detection accuracy≤±3%F.S (Higher precision can be customized)
Linearity≤±2%Repeatability≤±2%Uncertainty≤±2%
Response timeT90≤30 secondsRecovery time≤30秒
Signal OutputBus-based RS485 (RTU), three-wire 4~20mA, relay (passive or active output)
Optional: 0~20mA, 1~5V, 0~5V, 0~10V, wireless transmission, network transmission, SMS alarm.
Operating EnvironmentTemperature: -40℃～+70℃, Humidity: ≤95%RH (standard) for non-condensing environments.
For use in condensing environments, customization is required or the operating environment must be specified when ordering.
Display method1.7-inch high-definition color screen with a resolution of 320×240; optional: high-brightness LED display.
Operating voltage12~36V (DC), standard power supply for a single unit is 24V, 1A or greater DC switching power supply or regulated power supply;
Operating modeFixed installation, online detection, diffusion measurement; optional pipeline type, flow-through type, and pump-suction type measurement.
Installation methodPipeline type, wall-mounted type. The working pressure of the pipeline type is atmospheric pressure ±30%; pressure reduction is required for pressure exceeding this range.
Alarm MethodDefault 1 channel, optional 2 channels of passive contact (dry contact) output, alarm points can be set.
Optional integrated or split-type audible and visual alarm.
Electrical Interface3/4NPT, optional 1/2NPT, M20X1.5.
Connecting CableThree-wire system 4~20mA, select three-core shielded cable; RS485, select four-core; shielding layer grounded.
Protection ClassIP65
Explosion-proof TypeExplosion-proof type.
Explosion-proof MarkExdⅡCT6Gb
Dimensions230×210×90mm (L×H×W) with light; 230×152×90mm (L×H×W) without light.
Weight1600g
Standard AccessoriesInstruction manual, certificate of conformity, outer packaging box;
Optional AccessoriesIntegrated sound and light alarm, split sound and light alarm, 24V DC regulated power supply;
Accessories for computer monitoring: free host computer software, RS485/RS232 converter, laptops without RS232 interface also need USB/RS232 conversion cable, and if network transmission is required, a TCP/IP converter is also needed.
Wireless transmission (optional)Data can be wirelessly transmitted to mobile phones, remote monitoring centers, monitoring computers, and other monitoring equipment. The host computer can then perform data analysis, storage, and printing functions.
Preprocessing (optional)Normal temperature and high humidity pretreatment systems, high temperature and high humidity pretreatment systems, and high temperature, high humidity, and high dust pretreatment systems.
Mounting accessoriesOptional accessories: Wall-mounted brackets, pipe mounting clips (1/4″ and 1/6″ inch pipes).
Stainless steel threaded weld bead or flange for pipe mounting (pipe or flange size must be specified, such as DN50, DN15, etc.),
Rain cover, 24VDC or 220AC sampling pump (sampling distance 10 meters), vacuum pump (sampling distance greater than 40 meters)
24V switching power supply, pressure reducing valve, flow meter.
ApplicationsSuitable for all applications requiring fixed installation and online monitoring of gas concentration, including gas, oil, petrochemical, oil field, oil depot, chemical, metallurgical, and coking plants.

Commonly Detected Gases

ModelDetected Gases:ModelDetected Gases:ModelDetected Gases:
EXCombustible Gas (EX) M3Methane (CH4) O2Oxygen (O2)
C1Carbon Monoxide (CO) C2Carbon dioxide (CO2) Q1Formaldehyde (CH2O)
O3Ozone (O3) Y2Hydrogen sulfide (H2S) S2Sulfur dioxide (SO2)
L3Chlorine (Cl2) N3Ammonia (NH3) H1Hydrogen (H2)
HZ3Hydrogen Cyanide (HCN) PX3Phosphine (PH3) CX3Chlorine dioxide (CLO2)
E1Ethylene Oxide (ETO) TX3Phosgene (COCl2) SH4Silane (SiH4)
F2Fluorine (F2) FX2Hydrogen fluoride (HF) SX3Sulphoyl fluoride (SO2F2)
HEHelium (He) VOCVOC/TVOC FX1Hydrogen bromide (HBr)
 B2Diborane (B2H6) AX3Arsine (AsH3) G3Germanane (GeH4)
 NH2Hydrazine, Hydrazine (N2H4) P2Tetrahydrothiophene (THT) R2Bromine (Br2)
 G2Acetylene (C2H2) C5Ethylene (C2H4) Q4Acetaldehyde
 E5Ethanol (C2H6O) E4Methanol (CH4O) CS2Carbon disulfide (CS2)
 FX3Acrylonitrile TP1Methylamine N2Nitrogen (N2)
 I2Iodine (I2) N4Nitrogen oxides (NOx) CX6Benzene (C6H6)
 CX7Toluene (C7H8) CX8Xylene (C8H10) CTStyrene (C8H8)
 LX4Vinyl Chloride (C2H3Cl) CH3Mbromomethane (CH3Br)

Note: For other gases not listed in the table above, please call for inquiries.

Technical Support

VOCs, or Volatile Organic Compounds, are a class of organic compounds that are easily volatile at room temperature. They are composed of carbon (C) and hydrogen (H) elements and can originate from various chemical substances, including solvents, fuels, paints, and cleaning agents. VOCs are widespread in our lives, but many people do not have a deep understanding of them.

Based on their chemical structure, volatile organic compounds (VOCs) can be further divided into eight categories: alkanes, aromatic hydrocarbons, alkenes, halogenated hydrocarbons, esters, aldehydes, ketones, and other compounds. From an environmental perspective, it mainly refers to the chemically reactive volatile organic compounds. Common VOCs include benzene, toluene, xylene, styrene, trichloroethylene, chloroform, trichloroethane, diisocyanate (TDI), and toluene diisocyanate.

VOCs pose certain hazards to human health and the environment. First, VOCs can irritate and damage the human respiratory system. Long-term exposure to high concentrations of VOCs may lead to symptoms such as headaches, eye pain, coughing, and difficulty breathing, and may even cause serious respiratory diseases.

Second, VOCs are one of the main raw materials for photochemical reactions. They react with nitrogen oxides in the atmosphere to form ozone and fine particulate matter, polluting air quality. Furthermore, VOCs participate in the formation of photochemical smog, negatively impacting atmospheric visibility.

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VOC monitoring is achieved using VOC sensors. These sensors are specifically designed to detect and measure volatile organic compounds. They monitor the concentration of leaked and accumulated volatile organic compounds in ambient air in real time. When the detected VOC concentration exceeds the standard, an audible and visual alarm is triggered, and the exhaust fan is automatically controlled for ventilation. Simultaneously, the VOC concentration value and alarm status are displayed in real time on the monitoring host in the control room.

The most typical common characteristic of VOCs is their volatility. Many VOCs are prone to chemical reactions (reactivity). Currently known VOCs can undergo many chemical reactions in the air, the most important types of reactions including:

  1. VOCs react with hydroxyl radicals, being oxidized into organic free radicals, and then further decomposed and reacted;
  2. Some VOCs containing double bonds (such as alkenes and dienes) react with ozone to form diradicals, which then further decompose and react;
  3. A few oxygen-containing organic compounds, such as formaldehyde, acetone, and other aldehyde and ketone VOCs, can be directly decomposed by light, forming free radicals, thereby triggering more reactions.
  4. In addition, some VOCs are toxic and harmful to human health, such as benzene and toluene.

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VOCs (Volatile Organic Compounds) are widely present in residential and industrial environments. The photochemical smog they form in the atmosphere is largely carcinogenic, teratogenic, and mutagenic, posing significant threats to the environment and human health.

Many countries have enacted laws to restrict VOC emissions and have included VOCs in their monitoring programs. The United States’ automatic photochemical smog monitoring system includes 56 VOCs, while Europe has listed more than 30.

Online VOC monitoring equipment and technologies vary widely. In practice, monitoring and analysis systems differ significantly across industries, directly impacting the accuracy of monitoring data. In the future, VOC detection will evolve towards faster, more accurate, and more convenient methods. Technological innovation will continuously improve detection sensitivity and accuracy, and the application areas will continue to expand and deepen.

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