Bursting Disc, POS-A-SET®

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


A 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





If you have any questions please don`t hesitate to contact Thurne specialist directly:

Thurne Baltic

Andris Putnins
Product Sales Manager
Product Sales Manager B.Sc. Chemical Engineering, M.Sc. Materials Science

Phone number

Direct phone: +371 6616 3763 Mobile phone: +371 2689 6799

Thurne Denmark


Thurne Finland

Olli-Pekka Tikkanen
Product Sales Manager
Product Sales Manager B. Sc. Chemical Engineering

Phone number

Mobile phone: +358 40 730 8464

Thurne Sweden, Norway

Johan Andersen
Product Sales Manager
Product Sales Manager Industrial Engineering

Phone number

Direct phone: +46 (0)8 - 55 76 93 37 Mobile phone: +46 70 781 37 80

Thurne Poland

Robert Trambacz
Head of Sales, Poland
Head of Sales, Poland M.Sc. Mechanical Engineering

Phone number

Mobile phone: + 48 505 558 761