Pressure Relief Manway
CNC121 — Emergency relief manhole cover
Non-sparking emergency relief manhole covers provide access to low-pressure storage tanks and emergency venting capacity in the event of fire.
Select options
Applications and features
The CNC121/122 series is used on bulk storage tanks, including floating-roof tanks. Other applications include low-pressure gas pipeline systems, digesters and gas holders. Sizes range from 10 inch (250 mm) to 36 inch (900 mm).
- A hinged pallet can be lifted manually for tank cleaning and inspection, without gasket replacement or unbolting.
- A range of sizes and materials is available.
- A wide range of pressure settings provides tank protection with minimum gas loss.
- Low-cost maintenance.
- Free computerised valve sizing to API 2000.
Principle of operation
Emergency relief manways provide additional venting when a fire around a storage tank creates a venting requirement beyond the capacity of the pressure relief vent. The pallet lifts at a predetermined pressure, providing a large venting area.
A PTFE insert provides a tight seal below the set pressure between the pallet and the corrosion-resistant seat.
Construction
Setting arrangements
