Why would a rupture disk be installed upstream of a PRV?

• A. To protect PRV from corrosion
• B. To relieve excess pressure before PRV
• C. To provide visual indication of pressure
• D. To filter contaminants

Answer: (A)

A rupture disk upstream of a PRV is there to protect the valve itself. The disk acts as a sacrificial barrier that ruptures at a set pressure, venting the process stream before it reaches the relief valve. By taking the brunt of corrosion, erosion, or fouling in a harsh service, the disk keeps the downstream PRV in better condition and ready to perform its job when needed. Once the disk has vented (or if pressure keeps rising), the PRV can still provide controlled relief afterward. It’s not about signaling pressure, filtering, or primarily relieving before the valve; it’s about safeguarding the downstream relief device from damage in challenging service.