Shenzhen Zhongnuo Inspection Technology Co., Ltd. specializes in the calibration, certification, and metrological services for gas alarms, flammable gas detectors, toxic and harmful gas detectors, and other equipment in various locations. We offer nationwide services to address electrical safety and explosion-proof fire prevention issues for clients, contributing to safe production.
Standard for certification and calibration of flammable and toxic gas detectors:
Standard GB/T50493-2019 "Design Standard for Detection and Alarm Systems of Combustible and Toxic Gases in Petroleum and Chemical Industry"
GB12358-2006 General Technical Requirements for Environmental Gas Detection and Alarm Instruments in Workplace
JJG 693-2011 "Regulation for Calibration of Combustible Gas Detectors"

Gas Standard Material
We use gas standard substances of the same type as the gas measured by the instrument, such as methane or ethane, or alternative substances like isopropanol. If the instrument does not specify the type of gas being measured, the concentration of the gas, such as methane, ethane, or报警设定点的气体, is approximately 60% of the full scale. The expanded uncertainty of the standard gas can be adopted, and the uncertainty is not more than % (k=1% for body standard substances). The flow indication error of the repetitive dilution device should not be higher than the concentration of the gas standard substance. The concentration unit of the dilution device for gas standard substances should be converted to match the unit of the tested instrument, and the discrepancy should not exceed 0.%.

Calibration Method
Appearance and structure
Inspect visually and by touch according to the requirements of Section 4.1.
Logos and Branding
Inspection to be conducted in accordance with requirement 4.2.
Power-on Inspection
Inspect visually and by touch, in accordance with 4.3 requirements, to check the 5.3.4 alarm function and alarm action values.
Introduce a standard gas substance with a concentration exceeding the alarm set point, causing the instrument to trigger an alarm. Observe whether the instrument's sound and light alarm functions normally and record the instrument's reading when the alarm is triggered. Repeat the measurement three times, and the arithmetic mean of the three readings is the instrument's alarm trigger value.

Regulatory Testing Content and Methods for Combustible Gas Detectors
Annually, we conduct annual inspections on the sensors of commercial and industrial alarm systems, primarily checking for measurement errors, repeatability, drift, and response times to ensure they meet standards. Additionally, we verify the suitability of the alarm system's installation location and whether it is affected by interference from other equipment.
Shenzhen ZhongNuo Testing Technology Co., Ltd. is a third-party institution specializing in electrical safety, electrical explosion-proofing, gas alarms, and toxic and harmful gas alarm instruments for regular inspections, metrological measurements, and calibrations. We are qualified to provide solutions for fire and explosion prevention issues for our clients.