iSave 21 Plus

Summary

Product Identification

The Danfoss iSave 21 Plus and iSave 40 are Energy Recovery Devices (ERDs) designed for high-pressure applications, such as reverse osmosis (RO) systems. Each unit consists of an isobaric pressure exchanger, a high-pressure positive displacement booster pump, and an electric motor.

• Technology: The isobaric pressure exchangers are based on Danfoss APP pump technology, and the high-pressure booster pumps utilize the vane pump principle, allowing for a light and compact design.
• Lubrication: Moving parts are lubricated by the fluid itself.
• Flow Control: Vane pumps are fixed displacement, meaning flow is proportional to the driving shaft's revolutions, enabling flow control.
• Speed Control: The electric motor provides speed control for both the pressure exchanger and the booster pump on the same shaft, preventing overspin/overflushing.
• Materials: All critical parts are made of high corrosion-resistant materials, specifically Super Duplex 1.4410/UNS 32750 or Duplex 1.4462/UNS 32803.

Operating Limits

iSave without Motor

iSave 21 Plus (Code: 180F7015)

• Geometric displacement: 273 cm³/rev (16.7 in³/rev)
• Pressure:
  • Differential pressure HP in - HP out max.: 5 bar (72.5 psi)
  • HP max. outlet pressure: 83 barg (1200 psig)
  • HP min. inlet pressure: 15 barg (217 psig)
  • HP max. inlet pressure: 83 barg (1200 psig)
  • HP inlet min. pressure, intermittent: 3 barg (44 psig)
  • LP inlet max. pressure: 5 barg (72 psig)
  • LP inlet max. pressure intermittent: 10 barg (145 psig)
  • LP outlet min. pressure: 1 barg (14.5 psig)
  • LP differential LP in - out at HP max. flow: 0.9 bar (13 psi)
• Speed:
  • Min. speed: 500 rpm
  • Max. speed: 1500 rpm
• Flow:
  • HP outlet flow range at max. differential pressure: 6-22 m³/h (26-96 gpm)
  • Lubrication flow at 60 barg (871 psig) max.: 0.4 m³/h (1.8 gpm)
  • LP inlet max. flow: 33 m³/h (145 gpm)
• Torque:
  • Torque at max. differential pressure operation: 49 Nm (36 lbf-ft)
  • Max. starting torque (stick/slip): 50 Nm (37 lbf-ft)
• Temperature:
  • Media temperature: 2-40 °C (36-122 °F)
  • Ambient temperature: 0-50 °C (32-104 °F)
• Weight: 47 kg (103 lb)

iSave 40 (Code: 180F7011)

• Geometric displacement: 626 cm³/rev (38.2 in³/rev)
• Pressure:
  • Differential pressure HP in - HP out max.: 5 bar (72.5 psi)
  • HP max. outlet pressure: 83 barg (1200 psig)
  • HP min. inlet pressure: 20 barg (290 psig)
  • HP max. inlet pressure: 83 barg (1200 psig)
  • HP inlet min. pressure, intermittent: 3 barg (44 psig)
  • LP inlet max. pressure: 5 barg (72 psig)
  • LP inlet max. pressure intermittent: 10 barg (145 psig)
  • LP outlet min. pressure: 1 barg (14.5 psig)
  • LP differential LP in - out at HP max. flow: 1.2 bar (17.5 psi)
• Speed:
  • Min. speed: 600 rpm
  • Max. speed: 1200 rpm
• Flow:
  • HP outlet flow range at max. differential pressure: 21-41 m³/h (92-180.5 gpm)
  • Lubrication flow at 60 barg (871 psig) max.: 0.8 m³/h (3.5 gpm)
  • LP inlet max. flow: 67 m³/h (295 gpm)
• Torque:
  • Torque at max. differential pressure operation: 102 Nm (75 lbf-ft)
  • Max. starting torque (stick/slip): 150 Nm (110 lbf-ft)
• Temperature:
  • Media temperature: 2-40 °C (36-122 °F)
  • Ambient temperature: 0-50 °C (32-104 °F)
• Weight: 123 kg (271 lb)

Electrical

General Requirements

• A Variable Frequency Drive (VFD) is required to allow the motor to apply a constant torque from low speed to maximum speed.
• A VFD or soft starter must be used for ramp-up to prevent torque from exceeding the maximum allowable operation torque.
• The VFD must be able to deliver 140% start torque. Danfoss VFD types FC 301 and FC 302 are compatible.

iSave with IEC Motor (400 V, 50 Hz)

iSave 21 Plus (5.5 kW / 7.5 HP)

• Code number: 180F7016 (horizontal/vertical)
• Motor size: 5.5 kW (7.5 HP), IEC 132 S frame, 4 pole
• Speed: Nominal 1450 rpm, Min. 500 rpm, Max. 1500 rpm
• Rated current: 11 A
• Torque: Nominal 36 Nm (26.5 lbf-ft), Min. 27 Nm (20 lbf-ft)
• Protection: IP 55, Insulation Class B
• Sound pressure level max.: 78 dB(A)
• Weight: 105 kg (231 lb)
• Footprint (horizontal/vertical): 0.31 m² (3.34 foot²)
• Note: Differential pressure HP in - HP out max. is limited to 3 bar [44 psi].

iSave 21 Plus (7.5 kW / 10 HP)

• Code number: 180F7017 (horizontal/vertical)
• Motor size: 7.5 kW (10 HP), IEC 132 M frame, 4 pole
• Speed: Nominal 1450 rpm, Min. 500 rpm, Max. 1500 rpm
• Rated current: 15.2 A
• Torque: Nominal 49 Nm (36 lbf-ft), Min. 36 Nm (27 lbf-ft)
• Protection: IP 55, Insulation Class B
• Sound pressure level max.: 79 dB(A)
• Weight: 116 kg (255 lb)
• Footprint (horizontal/vertical): 0.32 m² (3.45 foot²)

iSave 40 (11 kW / 15 HP)

• Code number: 180F7001 (horizontal), 180F7003 (vertical)
• Motor size: 11 kW (15 HP), IEC 160 L frame, 6 pole
• Speed: Nominal 970 rpm, Min. 600 rpm, Max. 1100 rpm
• Rated current: 22 A
• Torque: Nominal 108 Nm (80 lbf-ft), Min. 95 Nm (70 lbf-ft)
• Protection: IP 55, Insulation Class B
• Sound pressure level max.: 84 dB(A)
• Weight: 254 kg (560 lb)
• Footprint (horizontal/vertical): 0.5/0.16 m² (5.38/1.72 foot²)

iSave 40 (15 kW / 20 HP)

• Code number: 180F7004 (horizontal), 180F7005 (vertical)
• Motor size: 15 kW (20 HP), IEC 180 L frame, 6 pole
• Speed: Nominal 970 rpm, Min. 600 rpm, Max. 1200 rpm
• Rated current: 30 A
• Torque: Nominal 146 Nm (107.7 lbf-ft), Min. 129 Nm (95 lbf-ft)
• Protection: IP 55, Insulation Class B
• Sound pressure level max.: 84 dB(A)
• Weight: 305 kg (672 lb)
• Footprint (horizontal/vertical): 0.54/0.17 m² (5.81/1.83 foot²)

iSave with NEMA Motor (High efficiency 460 V, 60 Hz)

iSave 21 Plus (7.5 kW / 10 HP)

• Code number: 180U0013 (horizontal/vertical)
• Motor size: 7.5 kW (10 HP), NEMA 215TC frame, 4 pole
• Speed: Nominal 1760 rpm, Min. continuous 500 rpm, Max. continuous 1500 rpm
• Rated current: 12.4 A
• Torque: Nominal 40 Nm (29.4 lbf-ft), Min. 20 Nm (14.7 lbf-ft)
• Protection: IP 55
• Sound pressure level max.: 78 dB(A)
• Weight: 152 kg (335 lb)
• Footprint (horizontal/vertical): 0.38 m² (4.09 foot²)
• Note: Differential pressure HP in - HP out max. is limited to 3 bar [44 psi].

iSave 21 Plus (11 kW / 15 HP)

• Code number: 180U0052 (horizontal/vertical)
• Motor size: 11 kW (15 HP), NEMA 254 frame, 4 pole
• Speed: Nominal 1765 rpm, Min. continuous 500 rpm, Max. continuous 1500 rpm
• Rated current: 18 A
• Torque: Nominal 59.7 Nm (44 lbf-ft), Min. 31 Nm (23 lbf-ft)
• Protection: IP 55
• Sound pressure level max.: 79 dB(A) (Tested with IEC motor)
• Weight: 206 kg (454 lb)
• Footprint (horizontal/vertical): 0.45/0.16 m² (4.85/1.72 foot²)

iSave 40 (15 kW / 20 HP)

• Code number: 180U0012 (horizontal), 180U0002 (vertical)
• Motor size: 15 kW (20 HP), NEMA 286TC frame, 6 pole
• Speed: Nominal 1175 rpm, Min. continuous 600 rpm, Max. continuous 1200 rpm
• Rated current: 24.2 A
• Torque: Nominal 119 Nm (88.2 lbf-ft), Min. 95 Nm (70 lbf-ft)
• Protection: IP 55
• Sound pressure level max.: 84 dB(A)
• Weight: 324 kg (715 lb)
• Footprint (horizontal/vertical): 0.65/0.23 m² (7.0/2.48 foot²)

Mechanical / Hydraulic

• Connections:
  • iSave 21 Plus: 2” Victaulic connections
  • iSave 40: 3” Victaulic connections
• Mounting:
  • Both iSave 21 Plus and iSave 40 can be mounted horizontally and vertically.
  • For vertical mounting of iSave 40, the electric motor must be placed at the top.
  • Horizontal iSave units without a base plate require support for both the iSave and motor, avoiding stress on the bell housing.
  • Horizontal iSave units with a base plate require a rigid mounting surface (e.g., concrete foundation, optional base frame, or suitable steel substructure).
  • Vertical iSave units are recommended to be mounted directly to the floor with bolts.
  • Flexible hoses are recommended between hard piping and the iSave to minimize vibrations and noise.
• Noise Level:
  • Noise levels are measured at max. speed, 80 barg pressure, and 5 bar booster pressure for the complete unit (iSave + motor).
  • Noise is influenced by speed (higher rpm = more pulsations/vibrations), pressure (higher pressure = more noise), mounting (rigid = more noise), connections (pipes = more noise), and VFD settings.

Noise Level (dB(A)) at 3 bar Booster Pressure

iSave 21 Plus

iSave 40

Feed Water

• Filtration: A true graded density, melt-blown depth filter cartridge rated at 3 µm (nominal) is recommended for incoming water to ensure optimum service life. Proper filter housing and cartridge end sealing are important; a second stage filter solution is recommended if there is a high risk of water bypass.
• Corrosion Resistance: All critical parts are made of Super Duplex 1.4410/UNS 32750 or Duplex 1.4462/UNS 32803, offering excellent corrosion resistance.
• Flushing: Always flush the iSave with fresh water when the system is shut down to minimize the risk of crevice corrosion.
• Salinity: Salinity increase at the membrane at 40% recovery rate is 2-3%.

Service and Maintenance

• Warranty: Danfoss guarantees 8,000 hours of service-free operation, or a maximum of 18 months from the date of production, provided the iSave has been running according to Danfoss specifications.
• Maintenance: Periodic inspection is recommended to replace worn parts and prevent potential breakdowns. Poor filtration is identified as the number one cause of iSave damage.
• Repair: In case of irregular function, contact Danfoss High Pressure Pumps.

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Disclaimer: This summary is based on extracted text and may not include all figures, footnotes, or the latest revisions from the official OEM PDF datasheet. Contractual data must always match the specific OEM PDF revision used on the project.

Official datasheet (PDF)

Lenntech datasheet mirror