Page 297 - Valve Selection Handbook

Table A-2.4 Section VIII Requirements

PRESSURE RELIEF DEVICE OPERATING REQUIREMENTS
ALLOWABLE VESSEL
OVERPRESSURE SET PRESSURE TOLERANCE
(ABOVE MAWP OR VESSEL SPECIFIED WITH RESPECT TO SET REQUIRED
APPLICATION DESIGN PRESSURE) PRESSURE SETTINGS PRESSURE BLOWDOWN
SECTION VIII Div. 1 & 2
All vessels unless an exception 10% or 3 psi - whichever is greater < MAWP of vessel ±2 psi up to and including 70 psi None specified
specified (UG-125C) (AR-150a) (UG-134a) (Afl-141)
±3% over 70 psi
Exceptions: 16% or 4 psi - whichever is greater One valve < MAWP, additional (UG-134 d1) (AR-120d)
When multiple devices are used (UG-125C1) (AR-150b) valves up to 105% of MAWP
(UG-134a) (AR-142a)
Supplemental device to protect 21%(UG-125c2) (AR-150C) Up to 110% MAWP Note:
against hazard due to fire (UG-134b) (AR-142b) Pressure relief valves for
compressible fluids having an
Device to protect liquified 20% (UG-125c3a) <MAWP(UG-125c3b) -0% +10% adjustable blowdown construction
compressed gas storage vessel in (UG-134d2) must be adjusted prior to initial
fire (Div. 1 only) capacity certification testing so
that blowdown does not exceed
Bursting disc Same as above Stamped burst pressure to meet ±2 psi up to and including 40 psi 5% of set pressure or 3 psi,
requirements noted above whichever is greater
(UG-134 - Note 56) (AR-140 - ±5% of stamped burst pressure at (UG-131 c3a) (AR-512)
Note 15) specified coincident disk
temperature (UG-127a1a)
(AR-131.1)
1 psi = 6.89 kPa
Table A-2.5 Section X Requirements

PRESSURE RELIEF DEVICE OPERATING RE(QUIREMENTS
ALLOWABLE VESSEL
OVERPRESSURE SET PRESSURE TOLERANCE
(ABOVE MAWP OR VESSEL SPECIFIED WITH RESPECT TO SET REQUIRED
APPLICATION DESIGN PRESSURE) PRESSURE SETTINGS PRESSURE BLOWDOWN
SECTION X
All vessels unless exception 10% or 3 psi - whichever is greater < Design pressure Ref. Section VIII None specified
specified (RR-130a) (RR-120) (RR-111)
Exceptions 16% or 4 psi - whichever is greater One valve < design pressure.
When multiple devices are used (RR-130b) Others up to 105% of design
pressure
Additional hazard due to fire 121%
(RR-130C)
1 psi = 6.89 kPa