Applications
| SEWON pressure and vacuum relief valve is designed to protect storage tanks from excessive pressure and/or vacuum created by thermal expansion (and contraction) and provide movement (in and out) of the tank while minimising product evaporation loss. | |
| Excess in pressure or vacuum may also cause permanent deformation to the tank or unbalance a vapor recovery system. | |
| The pressure and vacuum relief valve is installed on the storage tank roof. | |
| The valve should be mounted in conjuction with SEWON flame arrester to provide maximum protection against excessive pressure and vacuum while minimizing accidental ignition of flammable product vapour from external sources. |
Specifications
| Size Range | 1 1/2″ -12″ |
| Temperature Range | -45°C to 120°C |
| Set Pressure Range | 22 to 10,000 mmWC |
| Set Vacuum Range | 22 to 5,000 mmWC |
| End Connection | ANSI B16.5 Class 150, 300 |
Materials
| Body and Cover | Aluminium, Carbon Steel, SS304, SS316 |
| Seat | Aluminium, SS304, SS316 |
| Seating Diaphragm | Teflon (Weight loaded) |
| Viton O-Ring (Spring loaded) |
Operations
The tank pressure is applied to the underside of the pressure pallet and the topside of the vacuum pallet.
As long as the tank pressure remains within the valve pressure and vacuum setting, the pallet remains in contact with the seat rings and no
venting or breathing takes place.
The pressure pallet is lifted from its seat ring when the tank pressure reaches the valve pressure setting, allowing the excess pressure
to be vented to atmosphere. As the tank pressure drops below the valve pressure setting, the pressure pallet return to the closed position.
For negative pressure (vacuum), the vacuum pallet is lifted from its seat ring when the tank vacuum reaches the valve vacuum setting,
allowing air to flow into the tank to relieve the excess vacuum condition. The vacuum pallet returns to its normal position as the tank vacuum
drops below the valve vacuum setting.
