Analytical Instrumentation

  • ppm water in LPG and gas using Karl Fischer titration

ppm water in LPG and gas using Karl Fischer titration

Feb 19 2020 Read 573 Times

The effects of water in LPG

High water concentrations can have a detrimental effect on the many uses of liquified petroleum gas causing operational problems in customer equipment and downstream processes. Water can cause corrosion problems and create safety hazards during the storage, distribution and use of liquified petroleum gas (LPG) and pressurized low molecular weight hydrocarbons and their mixtures.

Previously the dryness of propane has been monitored with a “functional” test such as the freeze valve test method ASTM D2713 which demonstrates that excessive water content (dissolved water) will cause freeze-up difficulties in pressure reducing system. This method is limited to propane only.  Recent advances have been made in adapting coulometric Karl Fischer to analyse problematic samples such as LPG and LNG.  Coulometric Karl Fischer offers greater sensitivity and analyses both free and dissolved water i.e. total amount of water present.

Problems with Mercaptans, H2S and the mass flow controller. 

Interfering compounds such as Mercaptans and H2S can affect the accuracy of results when using coulometric Karl Fischer, whilst the use of an electronic mass flow for determining the gas flow(ml/min) requires calibrating for all gas types.

Both mercaptans and the use of the mass flow controller have made using coulometric Karl Fischer very difficult and unable to determine low ppm levels of water.  

That was until ECH Elektrochemie Halle developed a unique principle brining you the fully automated “Aquamax KF pro LPG” which fully complies with to the new ASTM D7995 method.  

Short analysis time, high sample throughput and removal of interferences    

Aquamax KF pro LPG comprise of a unique sample loop and analyse all LPG and gas mixtures without having the problem of manually preparing a mass flow controller.  The instrument does not require additional rinsing gases and only the actual sample is passed through the measuring cell. This allows 250 measurements within 48 hours without the need to replenish or switch any solvents which leads to considerable saving in terms of solvent and operator time.

Removal of the sulphur from the procedure means that no interference calculation is required. This eliminates any potential operation error in calculating the true result.  Aquamax KF pro LPG can also be used for LNG, technical gas, DME, Gas mixtures and CNG.

Conclusion

Aquamax KF pro LPG is the only coulometric Karl Fischer capable of 1ppm water in propane and butane whilst being ready to analyse water in all gas types without any changes or modifications.   

For all details and further information on how ECH achieve this, please contact us by email or visit our website.

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