This document specifies the sizing of safety valves and bursting discs for gas\/liquid two-phase flow in pressurized systems such as reactors, storage tanks, columns, heat exchangers, piping systems or transportation tanks\/containers, see Figure 2. The possible fluid states at the safety device inlet that can result in two-phase flow are given in Table 1. NOTE The pressures used in this document are absolute pressures, not gauge pressures.<\/p>\n
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| 123<\/td>\n | undefined <\/td>\n<\/tr>\n | ||||||
| 127<\/td>\n | Annex ZA(informative)Relationship between this European Standard and the essential safety requirements of Directive 2014\/68\/EU (Pressure Equipment Directive) aimed to be covered <\/td>\n<\/tr>\n | ||||||
| 130<\/td>\n | Foreword <\/td>\n<\/tr>\n | ||||||
| 131<\/td>\n | Introduction <\/td>\n<\/tr>\n | ||||||
| 132<\/td>\n | 1 \u200bScope 2 \u200bNormative references 3 \u200bTerms and definitions 3.1 \u200bGeneral <\/td>\n<\/tr>\n | ||||||
| 133<\/td>\n | 3.2 \u200bPressure <\/td>\n<\/tr>\n | ||||||
| 135<\/td>\n | 3.3 \u200bFlow rate <\/td>\n<\/tr>\n | ||||||
| 136<\/td>\n | 3.4 \u200bFlow area 3.5 \u200bFluid state 3.6 \u200bTemperature <\/td>\n<\/tr>\n | ||||||
| 137<\/td>\n | 4 \u200bSymbols and abbreviated terms and figures 4.1 \u200bSymbols <\/td>\n<\/tr>\n | ||||||
| 139<\/td>\n | 4.2 \u200bAbbreviated terms <\/td>\n<\/tr>\n | ||||||
| 140<\/td>\n | 4.3 \u200bFigures <\/td>\n<\/tr>\n | ||||||
| 142<\/td>\n | 5 \u200bApplication range of the method 5.1 \u200bGeneral 5.2 \u200bLimitations of the method for calculating the two-phase mass flux in safety devices 5.2.1 \u200bFlashing flow <\/td>\n<\/tr>\n | ||||||
| 143<\/td>\n | 5.2.2 \u200bCondensing flow 5.2.3 \u200bFlashing flow for multi-component liquids 5.2.4 \u200bDissolved gases <\/td>\n<\/tr>\n | ||||||
| 144<\/td>\n | 5.2.5 \u200bCompressibility coefficient \u03c9 5.3 \u200bLimitations of the method for calculating the mass flow rate required to be discharged 5.3.1 \u200bRate of temperature and pressure increase 5.3.2 \u200bImmiscible liquids 6 \u200bSizing steps 6.1 \u200bGeneral outline of sizing steps <\/td>\n<\/tr>\n | ||||||
| 145<\/td>\n | 6.2 \u200bStep 1 \u2014 Identification of the sizing case <\/td>\n<\/tr>\n | ||||||
| 146<\/td>\n | 6.3 \u200bStep 2 \u2014 Flow regime at the inlet of the vent line system 6.3.1 \u200bGeneral 6.3.2 \u200bPhenomenon of level swell 6.3.3 \u200bInfluence of liquid viscosity and foaming behaviour on the flow regime <\/td>\n<\/tr>\n | ||||||
| 148<\/td>\n | 6.3.4 \u200bPrediction of the flow regime (gas\/vapour or two-phase flow) <\/td>\n<\/tr>\n | ||||||
| 151<\/td>\n | 6.4 \u200bStep 3 \u2014 Calculation of the mass flow rate required to be discharged 6.4.1 \u200bGeneral 6.4.2 \u200bPressure increase caused by an excess in-flow <\/td>\n<\/tr>\n | ||||||
| 153<\/td>\n | 6.4.3 \u200bPressure increase due to external heating <\/td>\n<\/tr>\n | ||||||
| 156<\/td>\n | 6.4.4 \u200bPressure increase due to thermal runaway reactions <\/td>\n<\/tr>\n | ||||||
| 160<\/td>\n | 6.5 \u200bStep 4 \u2014 Calculation of the dischargeable mass flux through and pressure change in the vent line system 6.5.1 \u200bGeneral <\/td>\n<\/tr>\n | ||||||
| 163<\/td>\n | 6.5.2 \u200b Two-phase flow discharge coefficient, Kdr,2ph <\/td>\n<\/tr>\n | ||||||
| 164<\/td>\n | 6.5.3 \u200bDimensionless mass flow rate, C <\/td>\n<\/tr>\n | ||||||
| 165<\/td>\n | 6.5.4 \u200bCompressibility coefficient, \u03c9 (numerical method) <\/td>\n<\/tr>\n | ||||||
| 166<\/td>\n | 6.5.5 \u200bCalculation of the downstream stagnation condition 6.5.6 \u200bSlip correction for non-flashing two-phase flow <\/td>\n<\/tr>\n | ||||||
| 167<\/td>\n | 6.5.7 \u200bSlip correction for two-phase flow in straight pipes 6.6 \u200bStep 5 \u2014 Ensure proper operation of safety valve vent line systems under plant conditions 6.7 \u200bSimultaneous calculation of the dischargeable mass flux and pressure change in the vent line system <\/td>\n<\/tr>\n | ||||||
| 168<\/td>\n | 6.8 Summary of calculation procedure <\/td>\n<\/tr>\n | ||||||
| 175<\/td>\n | Annex A (informative) Identification of sizing scenarios <\/td>\n<\/tr>\n | ||||||
| 177<\/td>\n | Annex B (informative) Example calculation of the mass flow rate to be discharged <\/td>\n<\/tr>\n | ||||||
| 181<\/td>\n | Annex C (informative) Example of calculation of the dischargeable mass flux and pressure change through connected vent line systems <\/td>\n<\/tr>\n | ||||||
| 198<\/td>\n | Annex D (informative) Environmental factor <\/td>\n<\/tr>\n | ||||||
| 199<\/td>\n | Bibliography <\/td>\n<\/tr>\n<\/table>\n","protected":false},"excerpt":{"rendered":" Tracked Changes. Safety devices for protection against excessive pressure – Sizing of safety valves and bursting discs for gas\/liquid two-phase flow<\/b><\/p>\n |