The Duracid NF membrane element is engineered to operate continuously under extreme acid conditions where pH is at or below zero.
The family of Duracid proprietary thin-film nanofiltration membrane elements is characterized by an approximate molecular weight cut-off of 150-200 Dalton for uncharged organic molecules. Divalent and multivalent ions are preferentially rejected by the membrane while monovalent ions and mineral acids commonly have full transmission through the membrane (transmission can vary depending upon feed concentration and composition). Since mineral acids and monovalent ions have high passage through the membrane, these substances have a minor contribution to the osmotic pressure.
Among other applications, Duracid NF Elements are used for acid purification and metals concentration in low pH streams. They feature patented feed spacers, polysulfone parts, and a fiberglass outer wrap. All materials of construction are low pH tolerant.
Typical Operating Pressure: 400 – 800 psi (2758 – 5516 kPa)
Typical Operating Flux: 5 – 14 GFD (9 – 24 LMH)
Clean Water Flux(CWF): 10-19 GFD (17-32 LMH) @ 225 psi (1551kPa)
Maximum Operating Pressure:
- 1200psi (8,273kPa) @ T < 77°F (25°C)
- 800psi (5,515kPa) @ T < 122°F (50°C)
- 600psi (4,137kPa) @ T < 158°F (70°C)
Maximum Temperature:
Continuous operation: 158°F (70°C)
Clean-In-Place (CIP): 158°F (70°C)
Continuous pH:
Continuous operation: < 10 (up to 70°C)
CIP pH:
- < 11.0 @ T < 113°F (45°C)
- < 10.5 @ T < 131⁰F (55°C)
- < 10.0 @ T < 158°F (70°C)
Chlorine Tolerance: 500 ppm x hours, dechlorination recommended