Definitions/Terms

CCRO	Closed Circuit Reverse Osmosis
CC Mode	System operation where FEED flow = PERMEATE flow (no concentrate to drain).
CC₁	First closed circuit cycle (following PF mode). Lowest permeate conductivity and pressure.
CC_FINAL	Last closed circuit cycle (right before PF mode). Highest permeate conductivity and pressure.
One Cycle	One cycle is the volume of the system passing through all the membranes in series. The concept is similar to a stage in traditional RO. The duration or time for one cycle is equal to the system volume divided by the circulation flow rate).
Total Cycles	1 PF cycle + all closed circuit (CC) cycles.
CC Cycles	Total cycles minus 1 PF cycle.
CC or Cycle Recovery	The recovery rate during CC Mode (approximately 50%). Same as traditional recovery calculation (Recovery = Permeate / Feed).
CC Sequence Duration	The time in closed circuit (where concentrate flow = 0).
Conc. Recycle	Concentrate flow rate per pressure vessel (PV). Default is 20 gpm (4.54 m³/h) per PV. Increasing will decrease cycle recovery (and associated warnings).
PF	Plug Flow
PF Mode	System operation where the unit is flushed with feed water (results in reduced permeate flow rate). Concentrated brine equal to the volume of system is flushed to drain during PF.
PF Recovery	Recovery rate during PF Mode (the default is set at 20%). Same as traditional recovery calculation (Recovery = Permeate / Feed).
Feed Ratio	Increased feed water flow rate during PF mode. Ratio of Feed Flow (PF Cycle) over Feed or Permeate Flow during CC Cycles. Default is 120% which is CC flow rate x 1.2.
PF Sequence Duration	The time in PF mode (time period when concentrate is flushed to drain).
Average Recovery	The average recovery (not to be confused with PF or CC recovery).
Complete Sequence Duration	PF + CC sequence duration.
CC System Volume	The volume of the RO unit (the volume flushed to drain during PF Mode).
Recirculation	The circulation pump flow rate (100% of concentrate is recirculated). This is equal to the Conc. Recycle input (flow calculator) x number of pressure vessels.
Pressure Vessel Size	Length of pressure vessel (PV), default is # Els per PV + 1x element spacer. Default value is 6 (i.e. 5x elements and 1x element spacer).
Permeate Volume Per Batch	Volume of permeate produced during PF and CC modes (one batch). This may impact permeate tank sizing.
Average Flows	The average of the PF and CC modes.
Average Flux Rate	The average of PF and CC modes. Same flux rate as traditional RO (steady-state).
CC Flux Rate	The flux rate during CC Mode.
PF Flux Rate	The flux rate during PF Mode.