Apparatus for calibrating gas detector in site, and method of gas distribution

Abstract

An on-site calibrator of gas detector consists of a gas bottle for storing high pressure gas, a pressure stabilizing valve connected with gas bottle through gas tube, a covered container, a high-speed quantitative solenoid valve for sending said gas to covered container, a microprocessor connected to high-speed quantitative solenoid valve and a power supply module for supplying power on said processor and said solenoid valve.

Description

technical field [0001] The invention relates to a simple preparation method of a mixed gas of two or more than two component gases, more specifically a gas detector field calibrator and a gas distribution method designed for preparing a certain concentration of mixed gas. Background technique [0002] The key part of the gas detector field calibration instrument is the mixed gas generation part. There are many methods for the preparation of the mixed gas (referred to as "gas distribution"), and the main applications are as follows: [0003] Static volume gas distribution method: refers to converting the percentage concentration of each component gas of a certain mixed gas into the volume of each gas, and injecting each component gas into a container (such as a leather bag) under normal pressure for mixing. Uniform, calibrated and then compressed into a high-pressure cylinder. This method is simple and accurate, but it is not suitable for the preparation of a large amount of...

AI Technical Summary

Problems solved by technology

This method can only be qualitative but not quantitative, and cannot truly reflect the working status of the detector

Taking methane as an example, the national standard stipulates that the alarm concentration value is 500-12500ppm, but when a lighter is used for calibration, the gas released is isobutane, and the liquid state released from the lighter becomes a gas state under normal pressure, directly entering the detection For detectors, the gas concentration felt by the gas sensor may reach hundreds of thousands of ppm, far exceeding the lower explosion limit of 50,000 ppm. The detector that can alarm under this condition cannot guarantee an effective alarm when a leak actually occurs. cause an accident

[0017] Standard gas method, return to the factory for calibration, remove from the site where the detector is installed, return to the manufacturer to use standard gas on site, and calibrate with a calibration cover. The disadvantage of this method is that it is expensive and requires heavy gas storage cylinders

And it cannot be calibrated and measured at multiple concentration points, so it is not suitable for on-site calibration of a large number of detectors

Still taking methane (natural gas) as an example, this method generally only carries standard gas with two concentrations of 500ppm and 12500ppm. When using 500ppm, it is judged whether the detector does not alarm at the low end, and whether it alarms at 12500ppmm, but the real alarm point cannot judge clearly;

[0018] Re-calibration in a laboratory with calibration conditions is costly and time-consuming, and it puts the monitored system in an out-of-monitoring state, which affects safety

Images