Dynamic behaviour of direct spring loaded pressure relief valves: III valves in liquid service

C.J. Hős, A.R. Champneys, K. Paul, M. McNeely

Research output: Contribution to journalArticle (Academic Journal)peer-review

22 Citations (Scopus)
704 Downloads (Pure)


Previous studies into direct-spring pressure relief valves connected to a tank via a straight pipe are adapted to take account of liquid sonic velocity. Good agreement is found between new experimental data and simulations of a coupled fluid-structure mathematical model. Upon increasing feed mass flow rate, there is a critical pipe length above which a quarter-wave instability occurs. The dependency is shown to be well approximated by a simple analytical formula derived from a reduced-order model. Liquid service valves are found to be stable for longer inlet pipes than for the gas case. However, the instabilities when they do occur are more violent and the valve is found to jump straight into chatter, in which it impacts repeatedly with its seat. Flutter-type oscillations are never observed. These observations are explained by finding that the quarter-wave Hopf bifurcation is subcritical. Water hammer effects can also be observed, which result in excessive overpressure values during chatter. In addition a new, Helmholtz-like instability — not encountered in gas service — is identified for short pipes with small reservoir volumes. This can also be predicted analytically and is shown to explain a valve-only instability found in previous work that incorporated significant mechanical damping.
Original languageEnglish
Pages (from-to)1-9
Number of pages9
JournalJournal of Loss Prevention in the Process Industries
Early online date4 Apr 2016
Publication statusPublished - Sept 2016

Structured keywords

  • Engineering Mathematics Research Group


  • pressure-relief valve
  • reduced order modeling
  • instability
  • quarter-wave
  • Hopf bifurcation
  • water hammer


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