POS-A-SET® Rupture Disc

Relieve ultra-low vacuum or positive pressure conditions with the highly accurate, bidirectional POS-A-SET rupture disc.

Our double-acting design allows the POS-A-SET to do the work of two rupture discs with just one installation point. It relieves low positive pressure (as low as 1 inwc) with a girdle and knife-blade assembly on one side, while slightly higher negative pressure is relieved from the other side with perforations and a pre-cut section.

The POS-A-SET’s easy-to-clean flat seat design reduces product buildup, making it easier to meet FDA requirements.

Looking for the CAL-VAC rupture disc? Nearly identical to the POS-A-SET rupture disc, the CAL-VAC relieves ultra low-pressure in the negative direction – the inverse of the POS-A-SET’s ultra-low relief in the positive direction. Contact us if you aren’t sure which you need.

Two sides to the POS-A-SET rupture disc

As system pressure approaches the burst pressure setting on the ultra-low positive pressure side, a girdle is loaded until it deflects back past a knife-blade assembly in the holder. As the girdle passes the knife blade, the seal is divided in a triangular pattern to relieve the pressure.

CAL-VAC rupture discs vs. POS-A-SET rupture discs

The difference between the CAL-VAC and the POS-A-SET is the orientation of pressure relief components. The CAL-VAC relieves ultra low-pressure in the vacuum (negative) pressure direction, while the POS-A-SET rupture disc relieves ultra-low pressure in the positive pressure direction.

On the higher-pressure side, the perforated metal top section, under tension loading, relieves pressure in the direction opposite the girdle. It incorporates CDC’s seven hole pattern at the apex of the rupture disc dome. Together, the seven-hole pattern and six pre-cut sections create a non-fragmenting design.

Additionally, the top section’s pre-punched holes provide optimum flow through the disc when relieving ultra low-pressure through the girdle.

Both designs:

  • Relieve pressure as low as 1 inwc differential
  • Are dual-acting, providing both both positive and negative pressure protection
  • Can be made to meet 3A sanitary standards when used with a sanitary fitting holder assembly
  • Provide lower maintenance costs and greater reliability compared to a valve, increasing your system productivity
  • Do not include moving parts, eliminating the possibility of mechanical malfunction

Nominal Size Range: 3″ – 12″ (80 mm – 300 mm)

Burst Pressure Range: Positive Pressure: 1 inwc – 115 inwc | Vacuum Pressure: 2 psig – 150 psig (0,138 barg – 10,3 barg)

Maximum Recommended Operating Ratio:Consult POS-A-SET literature

Seating Configuration: Flat seat

Service: Liquid or gas

BDI Alarm System Compatible?: Yes

ASME Code Symbol Stamp Available?: No

Materials not indicated or shown may be available by special design. Contact us for more information.

Industry Applications

Food & Beverage Processing
Food & Beverage Processing
Food & Beverage Processing

We understand that product purity and safety are critical in food-related industries, so we provide hygienic and aseptic vessels and piping to assure compliance with FDA and 3A requirements.

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