Selecting the Correct Blower

TMC Fluid Systems' Aquaculture Blowers are specially designed for aquaculture applications. These blowers deliver a constant flow rate of air, independent of the discharge pressure conditions. The flow rate is dependent, largely on the operating speed. Due to these constructional features it has the following distinct characteristics:

1. The flow is largely dependent on the operating speed
2. The input Power is largely dependent on the total pressure across the machine.
3. The suction and Discharge pressures are determined by the system conditions.
4. The temperature rise in air discharged is largely dependent on the working pressure.

Blower Selection: The right selection and installation of an air blower can result in substantial energy savings. For proper selection of blower, air volume and air pressure are the most important parameters. Air Volume: Is the quantity of air required generally measured in m3/hr (or cfm). It is the total air requirement of the plant and depends on the plant capacity or the quantity of water to be aerated. Detailed calculations are needed to establish the required air flow rate, based on initial oxygen levels, final oxygen levels desired, BOD demand, and oxygen transfer efficiency, etc. However, as a rule of thumb, air requirement per 100-tons of water can be taken as approximately 100-m3/hr for medium pore diffusion aeration systems (i.e. using stones). Accordingly, the total air requirement can be calculated based on the total quantity of water that needs to be aerated. Air Pressure: Is the minimum air pressure required to enable air to bubble through the water, through the immersed stones, after overcoming the total pipeline pressure drop from where the blower is mounted and installed all the way to the diffuser tank. Power: The power consumed by the blower is directly proportional to the air pressure. Consequently, pipe sizing and installation, system resistance, pressure drop across valves and elbows and bends should be adequately addressed. For a tank with a depth of 1.5-meters, the optimum pressure requirement should be about 2.5-psi (approximately 1,700-mmWg). A pressure gauge, installed at the discharge of the blower delivery line provides the total back pressure load on the blower. Higher back pressure indication may be due to:

1. High line losses due to small diameter distribution grid / piping
2. High air flow
3. Choked suction filter
4. Insufficient number of diffusers