1. The legal basis for VOCs testing

 1. Safety production regulations

    (1) "Regulations on the Safety Management of Hazardous Chemicals" (Order No. 344 of the State Council of the People's Republic of China)

      Article 18: Units that produce, store, and use hazardous chemicals shall install alarm devices at the places of production, storage and use.

    (2) "General Rules of Safety and Health Requirements for Production Process" (GB/T 12801 -2008)

        5.3.1.c: For the process that produces dangerous and harmful factors, monitoring and testing instruments should be configured.

    (3) "Production License Regulations" (State Council Order No. 397 2004)

       Article 6: To obtain a work safety license, an enterprise shall meet the following conditions for work safety:

       (11) There are major hazard source detection, assessment, monitoring measures and emergency response plans.

    (4) "Specifications for on-site safety monitoring equipment installation for major hazard sources of hazardous chemicals, tank farms" (AQ 3036-2010)

 2. Occupational health and hygiene regulations

    (1) "Law of the People's Republic of China on the Prevention and Control of Occupational Diseases"

      Article 23: For toxic and harmful workplaces where occupational injuries may occur, the employer shall install alarm devices.

    (2) "National Occupational Hygiene Standard-Design Hygiene Standard for Industrial Enterprises" (GBZ 1 -2010)

      6.1.6 The automatic alarm or detection device should be designed according to the technical development level of automatic alarm device in the workplace where acute occupational poisoning is likely to occur in combination with the production process and the characteristics of the poison.

    (3) "Occupational Exposure Limits for Hazardous Factors in the Workplace-Chemical Hazardous Factors" (GBZ2.1-2007)

    (4) "Regulations on Labor Protection in Workplaces Using Toxic Substances" (No. 352 of the State Council in 2002)

      Article 11: In workplaces that may suddenly leak a large amount of toxic substances or easily cause acute poisoning, set up automatic alarm devices.

 3. Environmental protection regulations

    (1) "National Environmental Protection "Twelfth Five-Year" Science and Technology Development Plan" (2011, Ministry of Environmental Protection)

      The article lists the "organic pollutant automatic monitoring system" as a "support key technology, equipment and product research and development" project.

    (2) "Twelfth Five-Year Plan for Air Pollution Prevention and Control in Key Areas" (2012, Ministry of Environmental Protection)

      The article stipulates that "industrial VOCs emissions shall be gradually installed with an online continuous monitoring system, and VOCs environmental monitoring facilities shall be installed at the plant boundary".

    (3) "Guiding Opinions on Promoting Joint Prevention and Control of Air Pollution and Improving Regional Air Quality" (Guobanfa [2010] No. 33)

      (23) Local environmental protection departments should strengthen the supervisory monitoring of key enterprises and promote the installation of online pollution source monitoring devices.

 4. Production and use regulations

    (1) "Code for Design of Detection and Alarm of Combustible Gas and Toxic Gas in Petrochemical Industry" (GB50493-2009)

    (2) "Code for Fire Protection Design of Petrochemical Enterprises" (GB50160-2008)

        Article 4.6.11: In the device that uses or produces Class A gas or Class A, B and A liquids, it is advisable to install combustible gas alarm probes according to the principle of combining regional control and key control.

2. The detection range of toxic VOCs

 1. Basis for determination

   (1) "Code for Design of Detection and Alarm of Combustible Gas and Toxic Gas in Petrochemical Industry" (GB50493-2009)

     5.3.1(4) "The measurement range of toxic gas should be 0～300% of the maximum allowable concentration or 0～300% of the allowable concentration of short-term exposure".

   (2) "National Occupational Hygiene Standard-Occupational Exposure Limits of Hazardous Factors in Workplaces" (GBZ2.1—2007)

     4.1 Allowable concentration of chemical substances in the air in the workplace: PC-STEL of benzene is 10mg/m3 (2.87ppm)

   (3) "National Occupational Hygiene Standard-Specification for the Installation of Toxic Gas Detection and Alarm Devices in the Workplace" (GBZ/T223-2009)

      5.3 The detection range of the gas detector is 0～10 times PC-STEL, and the minimum detection volume is less than or equal to 0.5 times PC-STEL

 2. Benzene detection range

    (1) According to the above regulations, the detection range of benzene is: 2.87ppm×3 = 8.61 ppm ≈ 9 ppm

    (2) The actual measurement range of current international and domestic benzene detectors:

      ① Fixed: 0-10 / 20 ppm

      ② Portable: 0-1,000 /2,000 ppm (mainly used for leak detection)

3. Setting the alarm point of the toxic VOCs detector (take benzene as an example)

 1. Setting basis

   (1) "National Occupational Hygiene Standards-Design Hygiene Standards for Industrial Enterprises" (GBZ 1 -2010)

     6.1.6.3 The toxic alarm value should be based on the toxicity of the toxic gas and the actual situation of the site at least set the alarm value and the high value.

             The forecast value is 1/2 of MAC or PC-STEL. For chemicals without PC-STEL, the forecast value can be set at 1/2 of the corresponding over-limit multiple;

             The alarm value is the PC-STEL value, without PC-STEL chemical substances, the alarm value can be set at the corresponding over-limit multiple;

             The high reported value should be set after comprehensive consideration of various factors such as the toxicity of toxic gases, the conditions of the operators, the consequences of the accident, and the process equipment.

   (2) "Code for Design of Detection and Alarm of Combustible Gas and Toxic Gas in Petrochemical Industry" (GB50493-2009)

     5.3.3 (3) The alarm setting value of toxic gas should be less than or equal to 100% of the maximum allowable concentration or short-term exposure allowable concentration.

   (3) "Specifications for setting up site safety monitoring equipment for major hazard sources of hazardous chemicals, tank farms" (AQ3036-2010)

     4.3.6 Toxic gas alarm is divided into at least two levels, the first level alarm threshold is 75% of the maximum allowable concentration; the second level alarm value is 2 to 3 times the maximum allowable concentration.

2. Alarm setting value of benzene detector

      1) According to the above requirements, the alarm setting value of the benzene detector should be:

         ①Low-end alarm setting value: 1/2 of PC-STEL 3.08ppm (10mg/m3), about 1.5ppm (actually 3-5ppm);

         ② High-level alarm setting value: PC-STEL 3.08ppm (10mg/m3), about 3ppm (actually 5-7ppm).

     2) The recommended alarm setting value of benzene detector in practical application is:

         ①Low-end alarm setting value: generally 1.5-3ppm (range 0-10ppm);

        ② High-range alarm setting value: generally 3-7ppm (range 0-10ppm).