IGC Doc 7/03
Metering of cryogenic liquids
Metering of cryogenic liquids
Beschreibung
The aim of this document is to formulate, according to present knowledge and experience, the conditions under which cryogenic liquids can be satisfactorily metered during transfer, e.g. from the supplier's delivery tanker to the customer's equipment. The products concerned are the cryogenic gases, oxygen, nitrogen, argon and the non cryogenic gas carbon dioxide according to the recommendations of OIML (1) (2). For other liquefied gases the principles of the recommendations of this document may be used but also the recommendations of OIML (2) have to be taken into account. The document includes recommendations for approval procedures and verification tests of flow-meters and measuring Systems. The recommendations are taking into account the proposal for a European Directive (3). (Some European countries do not yet have regulations controlling the metering of cryogenic liquids.) However, in the formulation of this recommendation the knowledge and experience of the European gas industry have been applied to ensure that the document is soundly based and incorporates the best available technology. In addition, account has been taken of the many practical difficulties which arise in metering due to the particular properties of these liquids. In this way the recommendations have been designed to ensure the correct functioning and accuracy of flow meters used for cryogenic liquid metering. Installation features and methods of operation are both highly significant factors in accurate metering of cryogenic liquids. These are dealt with in some detail in the document. In order to make it a document of continuing usefulness, at least in the short term, account has also been taken of such known meter operating principles as are likely to be introduced in the foreseeable future.
