By Del Williams, technical writer
To increase equipment safety and reliability, a new rupture disk technology activates at a set burst pressure, but can “breathe” to relieve minor pressure fluctuations.
In industry settings, one-time-use rupture disks have long provided pressure relief on hydraulic and pneumatic equipment, serving as an effective passive safety mechanism to protect against potentially damaging overpressure or vacuum conditions. Each disk is typically designed to burst, rapidly changing from a leak-tight seal to a full diameter flow opening when a predetermined over or under pressure event occurs. At that point, the rupture disk needs to be replaced.
Rupture disks are a proven solution, particularly for the protection of certified pressure vessels whose protection is driven by the European Pressure Equipment Directive (PED) threshold of 0.5 bar and above and American Society of Mechanical Engineers (ASME) threshold of 15 psig and above.
Demand for this type of sealed, fluid-containing safety equipment is increasing for aseptic products in the health care, liquid food, and cosmetics industries and other applications where service pressures and even atmospheric pressure are much lower. Rupture disks are a critical component to seal fluid within the container under normal operating conditions, and they protect against overpressure caused by such events as external fire or an unexpected chemical reaction. Even noncombustible fluids can lead to overpressure conditions as they reach and exceed their boiling point.
With atmospheric storage equipment that is sealed, a particular challenge is that significant internal pressure fluctuations can also occur because of ambient temperature swings, particularly for vessels located outdoors or otherwise exposed to daily temperature excursions. Consider that at common equipment application temperatures (–40°F to +175°F/–40°C to +80°C), the shift in pressure in a sealed container can range from -3 to +3 psi, or -200 to +200 millibar.
“Although many fluids are stable under atmospheric pressure, when placed in a closed container even normal fluctuations in ambient temperature or equipment operation can generate overpressure (as temperature rises) or vacuum (as temperature falls),” said Geof Brazier, managing director of BS&B Safety Systems’ custom engineered products division. “Over time, this can compromise simple metallic and non-metallic container integrity due to flex and fatigue, leading to potential quality and maintenance issues and ultimately uncontrolled rupture of the container.”
Read the full article here.
