Safety Selector Valve Dual Pressure Relief Device System

• Balanced Design – Proper valve operation and lift are unaffected by back pressure. Costly and fragile metal bellows are not required.
• External, independent blowdown adjustment – Provides easy, accurate and repeatable settings. Reduces costly removal of valve or system downtime.
• ASME Section VIII Code Stamp – Certified National Board capacities for gas service assures user of independent third party flow rate verification.
• Reduced Maintenance Cost – Soft seats greatly extend service life, making costly and time consuming metal seat lapping unnecessary.
• Suited for Dirty or Wet Service – Non-flowing pilot minimizes entrance of dirt and formation of hydrates in the pilot. Due to low velocities within the pilot and supply tubing, most particles will drop out upstream of pilot inlet screen. Optional cartridge type pilot filter is available for extremely dirty services.
• Increased System Output – Because of total valve tightness to at least 95 percent of set pressure, the system can be operated nearer set pressure without valve leakage, resulting in greater system throughput.
• Unique Field Test Capability – This option allows accurate set pressure verification with valve in service. No system isolation block valve or rupture disc required.
• Reduced Product Loss and Pollution – Soft seats for premium tightness before and after relief cycles.
• Rugged Bracket Pilot Mounting – Extremely rigid mounting protects against vibration and careless handling. Shake table proven.
• Full Lift at Set Pressure – Allows D.O.T. installation to be set higher than Maximum Allowable Operating Pressure (MAOP), resulting in increased system throughput.
  

Sizes: 1" to 10"
Pressure Class: ANSI Class 150 to 2500
Maximum Temperature: 800°F [426°C]

Recommended Specifications:

• Changeover device inlet connection is to be the same size and rating as the pressure relief valve inlets.
• Pressure drop through the changeover device’s active side cannot exceed 3% with pressure relief valve fully open.
• Changeover device is to have external indicator, showing which side is active.
• Provisions for double padlocking in either position are required.
• A valve bleed port must be located under each pressure relief valve connection for pressure venting under the inactive pressure relief valve.