LPLV rupture disc: composite with full vacuum support

In short: The LPLV is the variant of the LPL composite disc designed to withstand full vacuum. It keeps the fluoropolymer protection on inlet and outlet, and adds a metal support that prevents the dome from collapsing when the equipment pressure falls below atmospheric.

How it works

A domed composite-type disc is designed to burst when pressure pushes from the concave side. If the vessel goes into vacuum, the load is reversed: the atmosphere or the pressure on the discharge side pushes the dome toward the process. Without support, a thin dome can deform or reverse and, from that moment on, its burst pressure is no longer reliable. The vacuum support is a metal part shaped like the dome that backs it against that reverse load without hindering rupture in the normal direction.

The rest of the construction is that of the LPL: a metal top section that defines the burst, a fluoropolymer seal on the process side and a fluoropolymer lining on the outlet. With fluoropolymer on both faces, the internal metal parts are isolated from corrosive media, which, according to the manufacturer, extends the service life of the assembly.

The dome has seven holes at the apex and six radial pre-cut sections. This geometry guides the opening and, together with the seal, prevents fragmentation; it also makes it possible to use thicker metal while maintaining an operating/burst ratio of up to 80 %.

When it makes sense (and when it does not)

• Suitable for reactors, tanks or lines that are emptied, cooled or placed under vacuum during operation or cleaning.
• Recommended for primary or secondary relief with corrosive or deposit-forming fluids.
• Suitable for isolating a pressure relief valve; in the non-fragmenting version it helps control fugitive emissions.
• Not necessary if the system never drops below atmospheric pressure: in that case the LPL without support is simpler.
• Not recommended if normal operation exceeds 80 % of the marked burst pressure.

Data to specify it

• Marked burst pressure and coincident temperature.
• Maximum operating pressure and expected vacuum condition (partial or full), plus any back pressure at the discharge.
• Nominal diameter and type of disc holder.
• Fluids on both sides of the disc, to validate the fluoropolymer.
• Non-fragmenting version requirement.

From 1" (25 mm) up, each disc comes with a clearly visible flow direction tag; with vacuum support, installing the assembly backwards is a mistake that must be avoided.

To go deeper: Common rupture disc failures and Rupture disc glossary.

Descriptive sheet for educational purposes. For availability and a quote for this model, consult P&V Control Devices.