Parr Instrument Safety Rupture Disc Assemblies - Manual (Page 2)

Safety Rupture Disc Assemblies
P a r r I n s t r u m e n t C o m p a n y 2
The series 581HC discs for use in a 1/4” orifice are
Alloy 600 with a gold facing. This option is not
available for the 1/2” orifice series 708HC discs due
to their configuration.
Alternate materials such as Alloy C-276 and Tanta-
lum are available for either series disc for certain
ranges which varies with the different materials.
4. Allow for temperature effect.
The burst pressure for any metal rupture disc will
drop as the temperature is raised, although Alloy
600 discs are much more stable in this respect than
most other disc materials. An Alloy 600 disc will
retain about 90 percent of its rating when heated
from 22°C to 500°C. Alloy C276 discs are compa-
rable to Alloy 600 temperature for stability. Rupture
discs made of other materials, such as Tantalum,
will have entirely different temperature-pressure
profiles, usually losing strength much more rapidly
at elevated temperature.
5. Be alert to damage from over pressure.
Under normal operating conditions where the
pressure applied to a disc never exceeds 90 per-
cent of the burst rating there should be little or no
deterioration in the ability of the disc to function as
intended (unless it is affected by corrosion or other
external factors).
6. Provide safe venting.
The user must assume full responsibility for in-
stalling an adequate and safe venting system to
remove any toxic, flammable or volatile materials
which would be released if the rupture disc should
burst. Consideration must also be given to any fly-
ing particles, disc fragments or reaction materials
which might be carried with the discharge. Contact
Parr technical staff for use of knock-out pots. The
discharge port from the rupture disc must always
be directed away from all operating personnel and
preferably, extension piping should be attached to
the safety head to carry any discharge to a fume
hood or to any other area where vapors can be
released safely. Connectors are available on the
A888HC2 rupture disc assembly for attaching 1/4”
NPT female, 1/4” NPT male, or 3/8” OD tubing to
carry any discharge to a safe outlet. Be sure to
anchor the discharge end of the extension tubing
securely.
The A707HC2 and A1417HC rupture disc assem-
blies installed on one gallon and larger reactors
have a straight discharge with a 1/2” NPT male
pipe thread to which extension tubing should be
attached. Any extension piping attached to this
assembly must also be anchored securely.
7. Protect against loud noise.
When a rupture disc bursts the instantaneous
expulsion of gases and vapors at sonic velocities
creates a loud noise which may damage the hear-
ing of any individual in the general vicinity of the
apparatus. Extension tubing will minimize this re-
port, but individual ear protectors may be the only
effective way to fully protect individuals from this
hazard. Because of this potential hazard it is always
best to operate a pressure reactor in an isolated
area and to keep all unnecessary personnel away
from the equipment while it is under pressure.
8. Install replacement discs carefully.
When replacing a rupture disc, the domed side of
the disc must project toward the outlet or dis-
charge end of the assembly. If there is a choice
between a sharp edge and a rounded edge on the
orifice ring which bears against the domed side of
the disc, place the rounded edge – not the sharp
edge – against the disc. Apply a light coating of a
thread lubricant (such as Parr 424HC2 anti-seize
lube) to the surface of the orifice ring which con-
tacts the body plug, and to the faces of the orifice
cone which seals the assembly into the pressure
vessel or fitting. The installation will be easier
if you invert the assembly and the head before
screwing the parts into place and tightening the
compression body.
9. Rupture Discs rated at elevated temperatures:
The burst pressure of rupture discs rated at el-
evated temperatures will increase when used at
temperatures lower than the specification. The per-
centage increase in strength of the disc will be de-
pendent on the temperature profile of the material
of the disc. As such, rupture discs rated at elevated
temperatures may no longer provide suitable
over-pressure protection at lower temperatures.
The user is advised to exercise due diligence when
using rupture discs rated at elevated temperatures.
Customer Service
Questions concerning the effect of temperatures
on the burst rating of any particular rupture disc
should be addressed to the technical staff at Parr.
1-309-762-7716 • 1-800-872-7720
Fax: 1-309-762-9453
E-mail: [email protected]
http://www.parrinst.com