Oxygen, the gas essential for life, is far more complex in industrial applications than our day to day inhalation and exhalation suggests. Detailed ? especially in the chemical, pharmaceutical or medical engineering fields ? is, time and again, finding itself met with new challenges in working with oxygen.
Why is ?oil and grease free? so important in oxygen systems?
Oxygen itself isn’t flammable. However, it enables and encourages very strongly the combustion of other substances and will, in particular, result in a self-ignition of oil, grease along with other substances.
Materials which do not burn in air can burn very briskly and even spontaneously in oxygen or oxygen-enriched air. This stands, even though the enrichment is by a few percent.
Oil and grease (also ointments, gels and disinfectants) can react explosively in contact with oxygen.
Oxygen significantly increases the temperature of a flame and also the burn rate.
Special cleaning and testing procedures
Classification of contamination levels in accordance with ASTM G93-03:2004 ch. 11.4.3
As a manufacturer of high-quality measuring instruments, WIKA faces around the increased demands of the markets and develops special cleaning procedures specifically for its products. If, for instance, a CPG1500 digital pressure gauge is supposed for oxygen service (option ?Oxygen, oil and grease free for oxygen applications?), before packing, the instrument will once again be cleaned additionally and taken to the company?s own laboratory for residual hydrocarbon determination. As standard, in calibration technology, a hydrocarbon limit value of max. 200 mg/m� (per ISO 15001:2012) and for particles/fibers a limit value of 1000 �m is defined.
Steps in the calibration technology laboratory
The wetted parts ? specifically the pressure connection ? are rinsed with an extractant
The extractant is collected and analysed for foreign particles, and the hydrocarbon content is determined
A comparison of the measurement is completed with regards to the level classification in accordance with ASTM G93-03:2004 ch. 11.4.3
The wetted parts are rinsed again having an extractant
The extractant is collected and analysed for foreign particles, and the particle quantity is set
The evaluation of the particle quantity is carried out in accordance with ISO 15001 cat.1
Consequence of the procedure
Example certificate for CPG1500
The result of this determination, meaning the actual residual hydrocarbon content and number of particles, is documented in a 3.1 inspection certificate in accordance with DIN EN 10204 (see figure). The pressure connection of the cleaned and tested digital pressure gauge is provided with a protection cap. Subsequently, Enchant is sealed within foil. In addition, the product label shows the option ?oxygen, oil and grease free?. The determination of the residual hydrocarbon content is completed for each individual digital pressure gauge.
Note
More info on the CPG1500 may also be found on the WIKA website.