Setup of facilities for testing of gas measuring and sampling devices

Status:

completed 12/1995

Aims:

Measuring and sampling devices employed for the measurement of gases and vapours at workplaces must meet certain requirements specified in standards with regard to their measurement accuracy. Fulfilment of these requirements may be demonstrated by type testing performed by an accredited testing body. The BG Institute for Occupational Safety (BIA) has been accredited as a testing body for gas measuring and sampling devices. The task was therefore to set up facilities by means of which the requisite technical tests could be performed.

Activities/Methods:

A survey was first performed of the literature, and existing descriptions of test procedures (including VDI Rules) reviewed for their applicability. Two test assemblies were set up for the production of test gas atmospheres with defined gas concentrations. One of the test assemblies comprises a glass vessel with a volume of 400 litres into which a calculated quantity of the hazardous material is placed in liquid form, vaporized, and homogenized with a basic gas. Larger gas measuring devices can be tested in this vessel. In the second test assembly, a basic gas is pumped through a line in order to produce a test gas atmosphere dynamically. The hazardous substance is then metered in in liquid form, or mixed in in gaseous form. The temperature and moisture content of the test gas can be adjusted as required. The measuring devices to be tested, such as detector tubes, are exposed to the test gas concentration at the end of the process. The test gas concentration is verified in the case of both test assemblies with the aid of calibrated reference gas measuring instruments.

Results:

The gas measuring and sampling devices to be tested are subjected in the course of tests and examinations performed in the test assemblies to a range of gas concentrations, gas temperatures, moisture contents and disturbance components defined in standards. The measurement results from the objects under test are compared with the actual gas concentrations and fulfilment or otherwise of the standards requirements ascertained. Type tests of gas measuring and sampling devices are performed by the BIA with the aid of the test assemblies; they can also be used to test the calibration of the gas and vapour measuring devices employed by the BG measuring services.

Further informations:

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