Tennessee Wastewater Operator Practice Exam

How are the pressure and airflow rates from integrally geared single-stage blowers adjusted to meet process requirements?

1. By changing the impeller size

2. By adjusting the IGV and/or the DDV

3. By modifying the motor speed

4. By increasing the number of stages

The correct answer is: By adjusting the IGV and/or the DDV

Adjusting the pressure and airflow rates in integrally geared single-stage blowers is achieved by manipulating the inlet guide vanes (IGV) and/or the discharge diverter valve (DDV). The IGV helps regulate the amount of air entering the blower, allowing for fine-tuning of the airflow and subsequently the pressure, while the DDV helps control the discharge of air, ensuring the system maintains appropriate operating conditions and efficiency. This method is particularly effective in meeting specific process requirements because it allows for on-the-fly adjustments without necessitating physical modifications to the blower hardware. This flexibility can be crucial in dynamic environments where process conditions may change frequently. Changing the impeller size is a more permanent alteration that would require significant downtime and modification of the blower itself. Modifying the motor speed might not provide the precise control needed for both pressure and airflow, and simply increasing the number of stages is not applicable in the context of single-stage blowers, effective control is achieved through the adjustment of IGV and DDV.