Sampling of Liquidfied Gases
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Further Details: Steve McClure Tel: - +441376 536838 / +447703519426
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HS&E bulletin 07/2004
Recently, a serious incident occurred following the sampling of an LPG vessel. The inspector obtained hydrocarbon liquefied gas samples using two gas sample cylinders, commonly called ‘gas bombs’. These cylinders were delivered to a client’s laboratory for testing but the correct procedure for delivering the samples was not followed, partially because it had not been adequately communicated. Within a short time the bursting discs on the cylinders ruptured releasing the gas samples into the laboratory environment. If the releases had been close to live ignition sources or within a vehicle, the results could have been catastrophic.
The subsequent investigation revealed that the immediate cause of the rupture was primarily overfilling of the sample cylinder but further exacerbated by an increase in temperature between the filling source and the ambient laboratory temperature. A root cause was that the inspector had limited training and experience in sampling liquefied gases.
POINTS WORTH REMEMBERING:
➢ Bursting discs will rupture if the ullage space in the cylinder is less than 5%. ➢ Sampling cylinders must be fitted with an ullage tube that is designed to reduce the possibility of overfilling and normally allow an ullage space of approximately 20% to be achieved. ➢ Overfilling can occur if the cylinder is not fitted with an ullage tube, OR ➢ The cylinder is not filled in the vertical position, for example, horizontally, OR ➢ The cylinder is connected to the sampling point upside down with the ullage tube assembly at the bottom, OR ➢ The ullage tube is not ‘vented’.
WHAT YOU CAN DO: - ➢ Follow the procedure “BS EN ISO 4257:2001 Liquefied petroleum gases – Method of sampling”. ➢ Ensure that Inspectors
Further Details: Steve McClure Tel: - +441376 536838 / +447703519426
-----------------------
HS&E bulletin 07/2004
Recently, a serious incident occurred following the sampling of an LPG vessel. The inspector obtained hydrocarbon liquefied gas samples using two gas sample cylinders, commonly called ‘gas bombs’. These cylinders were delivered to a client’s laboratory for testing but the correct procedure for delivering the samples was not followed, partially because it had not been adequately communicated. Within a short time the bursting discs on the cylinders ruptured releasing the gas samples into the laboratory environment. If the releases had been close to live ignition sources or within a vehicle, the results could have been catastrophic.
The subsequent investigation revealed that the immediate cause of the rupture was primarily overfilling of the sample cylinder but further exacerbated by an increase in temperature between the filling source and the ambient laboratory temperature. A root cause was that the inspector had limited training and experience in sampling liquefied gases.
POINTS WORTH REMEMBERING:
➢ Bursting discs will rupture if the ullage space in the cylinder is less than 5%. ➢ Sampling cylinders must be fitted with an ullage tube that is designed to reduce the possibility of overfilling and normally allow an ullage space of approximately 20% to be achieved. ➢ Overfilling can occur if the cylinder is not fitted with an ullage tube, OR ➢ The cylinder is not filled in the vertical position, for example, horizontally, OR ➢ The cylinder is connected to the sampling point upside down with the ullage tube assembly at the bottom, OR ➢ The ullage tube is not ‘vented’.
WHAT YOU CAN DO: - ➢ Follow the procedure “BS EN ISO 4257:2001 Liquefied petroleum gases – Method of sampling”. ➢ Ensure that Inspectors