PRESSURE RELIEF DEVICES
This page lets you know the terms about relief devices such as relief valves, rupture disks,rupture pins, breather vents, and their characteristics.
DEALING WITH EXCESSIVE PRESSURE LOSS AT THE INLET AND EXIT LINES OF PRESSURE RELIEF VALVES.
1.0 Valve stability / chatter issue: How to eliminate them.
1.1 Required flow rate is < 25% of valve capacity. The valve is too big for the scenario.
1.2 Piping length issue:PRV inlet line or outlet line or both are too long.Shorten the lengths.
1.3 Sizing issue: PRV inlet line, or outlet line or both is undersized. Increase the size.
1.4 Upper blowdown adjusting ring is too high. Lower it.
2.0 Simple measures against inlet pressure loss
2.1 Avoid turns, elbows or use long-radius elbows.
2.2 Use multiple valves with staggered set points.
2.3 Increase valve blowdown:
Follow the rule: Pressure at valve inlet = Vessel pressure(psig) - inlet line loss % > blowdown %.
2.4 Use a smaller PRV or restrict the lift of a big PRV with a restricted lift.
2.5 Consider a pilot-operated PRV.

The difference among the terms: chattering, fluttering, and cycling of a relief valve.
Chattering is rapid opening and closing (cycling) with physical contacts with valve seat causing, noise, damage and failure.Fluttering is similar but without noise and physical contacts with seats. Cycling is repetitive opening and closing.The fluid writhes through the tortuous path from the inlet to the outlet of the PRV
RUPTURE DISKS: ISSUES YOU SHOULD KNOW ABOUT SOME DANGEROUS DESIGNS.
3.1 In a rupture disk & relief valve combination system, the space between the disk and relief valve must be vented to avoid catastrophic failure of the equipment. If you need help, seek expert guidance or write to me.
BUCKLING PINS: BENEFITS OF THE BUCKLING PIN YOU SHOULD KNOW.
4.1 The buckling pin actuates precisely at set point under compression load according to Euler's Law.
4.2 The buckling pins can be used under harsh applications such as slurry where rupture disks and relief valves cannot be used.
4.3. The buckling pins can be replaced without shutting down the operation unlike rupture disks and relief valves.
Popular vendors or makers of relief devices are (a) BS & B, Continental,Fike, OSECO, & ZOOK for rupture disk; (b) Consolidated, Crosby, Farris, GROTH, Henry Valve, KSEA(Lined Valves), Lesser, and REMBE for relief valve; (c) BS&B, VAREC for Flame Arresters.
To know more about this page, please write to Dilip K. Das at [email protected]

To buy Emergency Pressure Relief System Design authored by Dilip Das and published by AIChE/Wiley, Google search for the book.