The SideCar system, a specialized, yet uncomplicated and efficient process, to aerate RBCs. An understanding and application of the following rationales are important when designing or operating a SideCar aeration system.
SideCar Aeration functions just like all diffused aeration systems. Whether a single or multiple SCs operating from a single air source these principles apply.
The goal is for the system to create practically equal air flow (+/- 10%) through every Flexcap diffuser across the entire system over the range of design air rates. No throtting of valves is required to “balance” or “control” flows to portions of the system. Blowers are sized/selected to compensate for nominal tolerances in system pressures and dimensions.
Equalization of system air flow (as with all diffused aeration systems) relies on creating as close as possible identical pressure. This is accomplished by generous sizing of air supply piping to minimize pressure loss and setting the tops of all diffusers at the same (+/-½” max) submergence. If tank floor elevations are sloped or differ tank-to-tank the air header supports (rollers or trolleys) are selected or designed to create this uniform submergence.
The air application rate (typically ~5 CFM/ft. of RBC media length for continuous “Process” air and 2X that for occasional “air scour”) is determined by the blower capacity and number of RBCs on line. For example, if a single 250 CFM blower services two (2) 3-stage RBCs to air scour the RBCs one at a time, the full capacity of that blower would be ramped up to a single RBC by systematically closing the stage valves on the alternate unit. Conversely, for a “soft start” or 0.5X air application rate (2-3 CFM/ft.) specified in the manual, one blower can provide air to four (4) SideCars.
Valves on blower discharge and RBC supply pipes are for ON-OFF isolation purposes, FULL OPEN or CLOSED, not for throttling or air flow balancing. It is impossible to observe or estimate air flow under an RBC.
Pressure gauges, typically on each blower discharge pipe before check valves and at the extremity of air supply piping by SC take-off, are for monitoring (not control) simply to assure adequate pressure. (1.0 PSI = 2.31’ water = 27.68” water) typical SC “Process” operating pressure at manifold inlet 2.5 – 2.7 PSI for 25’ diameter RBC depending on tank depth and perhaps 0.1 PSI higher for 2x air scour. These respective pressures should not vary much from initial startup over the life of the system.