Improved conformance testing for gravimetric sorption analysers

Louise Smyth

Hiden Isochema has introduced a NIST traceable method for assessing the combined pressure, uptake and temperature measurements of gravimetric sorption systems.

An in situ densitometry procedure is used to simultaneously determine mass and volume of an externally calibrated float. The volume is measured within 0.001 cc across the analyser pressure range and is equivalent to a 1 µg (microgram) air displacement at standard temperature and pressure.

A specific tolerance is calculated from the test conditions and the sensor specifications of a given analyser to yield a clear pass / fail condition for certification. The method also enables both the absolute combined accuracy and linearity to be quantified in specific operating conditions since it can be applied to any species including non-ideal gases such as carbon dioxide and methane.

This rigorous conformance testing is applied as standard to all new IGA and XEMIS series analysers and also during routine instrument servicing. A test kit and accompanying software protocol is also offered for user conformance testing to suit the requirements of their site quality management system.