WHY CALIBRATION IS IMPORTANT? The accuracy of all measuring devices degrades over time. This is typically caused by normal wear and tear. However, changes in inaccuracy can also be caused by electric or mechanical shock or a hazardous manufacturing environment (ex., oils, metal chips, etc.). Depending on the type of instrument and the environment in which it is being used, it may degrade very quickly or over a long period of time. The bottom line is that calibration improves the accuracy of the measuring device.
It is essential that any gas monitoring system should not only be calibrated at the time of installation, but also checked regularly and re-calibrated as necessary. Checks must be made using an accurately calibrated standard gas mixture so that the zero and ‘span’ levels can be set correctly on the controller. flammable gas detectors (%LEL) and also guidance on the calibration of toxic gas detectors Typically, checks should initially be made at weekly intervals but the periods can be extended as operational experience is gained. Where two alarm levels are required, these are normally set at 20-25% LEL for the lower level and 50-55% LEL for the upper level. Older (and lower cost) systems require two people to check and calibrate, one to expose the sensor to a flow of gas and the other to check the reading shown on the scale of its control unit. Adjustments are then made at the controller to the zero and span potentiometers until the reading exactly matches that of the gas mixture concentration.
Gas Detector Calibration: A gas monitor calibration consists of setting air zero grade and sensitivity (span). It is required to perform it regularly for both portable gas detectors and fixed gas detection systems. -Air zero grade setting: The ( air zero grade setting ) of a sensor sets ambient air as the reference value. It is therefore essential that this ( reference air ) is pure in order to avoid false measurements. In case of any doubt, it is recommended to use an( air zero grade ) cylinder (synthetic air) rather than ambient air. This is all the more important for CO2 detectors (carbon dioxide) as it is naturally present in ambient air (about 400 ppm) and will distort CO2 measured values. For this gas, the ( zero ) shall be set with an ( air zero grade ) cylinder. -Sensitivity setup (calibration): The sensitivity setting (gas detector calibration) shall ideally be done with a calibration gas cylinder of the targeted gas. The concentration has to be set between 20 and 80% of the measuring range while making sure of being able to activate every gas detector's alarm thresholds. In some cases, there are no calibration gas cylinders (some gases are not available for sale). Thus using an interfering gas with precaution is therefore recommended. -BUMP TEST: Performing a bump test is highly recommended in order to control the proper operation of any device between two calibrations or before entering confined spaces. This gas detector check is made by injecting a known concentration of gas to confirm the proper operation of the sensor (response time to the gas) and the alarm activation on the device.
Gas detector calibration certificate: A calibration certificate must be edited after any calibration of a gas detector. This certificate clearly indicates references and features of the device, each sensor measuring range, batch numbers, and validity date of used cylinders. This calibration certificate must also contain the calibration date and its validity period and the next calibration date. GIANTS provides calibration certificates for all monitoring devices, portable multi-gas detectors, portable single gas detectors, and fixed gas monitors. For maintenance, periodical checkings, and calibration of gas detectors we offer a wide range of classic or customizable gaseous mixtures in lightweight disposable single-use cylinders. Our available offer gathers a full range of gases from classic LEL binary mixtures up to complex and multiple mixtures used in laboratories with very low-level concentrations. Gaseous mixtures are gravimetrically mixed under the requirements of the ISO6142 standard. They ensure accuracy, optimal stability, and maximal shelf life. calibrate…