LPL rupture disc: fluoropolymer composite for corrosive service

In short: The LPL is a composite rupture disc: a metal dome that defines the burst pressure, a seal on the process side, and a fluoropolymer lining on the outlet. It is designed for corrosive or fouling-prone services, with operating pressures of up to 80 % of the marked burst pressure.

How it works

In a composite disc each layer performs a different task. The metal top section provides the mechanical strength and sets the burst point. The seal on the process side ensures tightness and keeps the fluid from touching the metal directly. In the LPL a fluoropolymer lining is added on the outlet face, so the metal is protected on both sides against corrosive vapors that may arrive from the discharge system.

The dome has a pattern of seven holes at the apex and six pre-cut sections radiating from the center. On reaching the burst pressure, the dome opens along those weakened lines instead of tearing randomly; together with the fluoropolymer seal, this allows an opening without fragments breaking off. According to the manufacturer, this design accepts thicker materials without losing the 80 % operating/burst ratio.

The LPL tolerates static, cyclic or pulsating conditions. What it does not do on its own is withstand full vacuum: for that it needs a vacuum support, which is precisely what distinguishes its LPLV variant.

When it makes sense (and when it does not)

• It is suitable as a primary or secondary relief device in processes with aggressive fluids.
• Recommended upstream of a pressure relief valve to isolate it from the process; the non-fragmenting version prevents disc debris from damaging the valve seat and helps control fugitive emissions.
• Suitable where the product tends to build up, since fluoropolymer surfaces offer less grip to deposits.
• Not recommended as is if the equipment can be left under full vacuum; in that case it must be ordered with vacuum support.
• Not recommended if the operating pressure exceeds 80 % of the marked burst pressure; another disc type or the set pressure would need to be reviewed.

Data to specify it

• Marked burst pressure and coincident temperature.
• Maximum operating pressure and type of service (static, cyclic or pulsating).
• Nominal diameter and the disc holder or flanges where it will be installed.
• Process fluid and discharge-side fluid, to confirm fluoropolymer compatibility.
• Whether a non-fragmenting version is required.
• Whether there is a vacuum risk and, therefore, a need for vacuum support.

Discs of 1" (25 mm) or larger include a flow direction tag for unambiguous orientation and inspection.

Learn more: Rupture disc materials and Rupture disc vs. pressure relief valve.

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