Pressure-relieving devices Special

Flow capacity testing The usually special testing of a pressure relief device to determine its operating characteristics, including measured relieving capacity. This tests whether the valve flows the capacity as stated in the literature or as per given flow coefficients, or to simply determine the flow coefficient of the valve as such. This is done on a spot-check basis by independent notified bodies in limited locations worldwide especially approved for that purpose. 

For the controlled removal of the liquid phase of a liquefied gas, a manual flow-control valve is used. Special liquid flow regulators are also available. Removal of the liquid must be done at the vapor pressure of the material. Care must be taken to prevent blockage of the gas line downstream from a user s heat exchanger, which would cause excessive pressure buildup in the heat exchanger and the cylinder. Pressure relief devices should be installed in all transfer lines to relieve any sudden and dangerous hydrostatic or vapor pressure buildups. 

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