Rupture Disk Outlet Pipe-Liquid

[RJB32482]

Hey Guys,
When sizing rupture disks with the coefficient of discharge method, what is the limit on the length and size of outlet pipe for liquid flow (certain % of pressure drop)?

Thanks.

 

[pleckner]

I invite you to read my 6-part series on rupture disks found at

http://www.cheresources.com/asiseeit.shtml.

In this series I discuss why you don't want to use the coefficient of discharge method to do your rupture disk sizing. Briefly, this method does NOT directly take into account piping and its use is restricted to the
“8 & 5 Rule”. This rule states that in order to use this method to size the rupture disk ALL of the following four conditions MUST be met:

1. The rupture disk must be installed within 8 pipe diameters of the vessel or other overpressure source.
2. The rupture disk discharge pipe must not exceed 5 pipe diameters.
3. The rupture disk must discharge directly to atmosphere.
4. The inlet and outlet piping is at least the same nominal pipe size as the rupture disk.

There is no rule governing pressure loss other than the fact that you cannot exceed the relieving vessel's design pressure (or MAWP) plus allowable overpressure when the system is in relief.