In municipal and industrial wastewater treatment, aeration is part of the secondary treatment process. The activated sludge process is the most common option in secondary treatment. In industrial use, a common method of aeration is air diffusion method, in which air is diffused into a receiving vessel containing counter-current flowing water, to remove dissolved gases, such as carbon dioxide, Hydrogen Sulfide or methane, and to oxidize dissolved metals such as iron. If air header flow rates being supplied by compressors are not sufficient, the secondary treatment process will be incomplete and may yield contaminated water to rivers and other environmental water sources.
To verify that proper flow rates are supplied to the lab’s pneumatic valves, an ECA Current Alarm Trip is used to alarm on low airflow conditions. The ECA comes standard with two SPDT alarm outputs and a TX option (24VDC @ 25mA) that powers the loop powered Airflow Sensor so no additional wiring to a separate 24DC auxiliary power supply is needed. Setpoints for the two alarms are set with front panel potentiometers adjustable from 0-110% of input span. This is very useful for NAMUR compliant type Airflow Sensors as one of the two alarms can be set at >21mA, indicating a failed transmitter condition per NAMUR standards. Field configurable via selectable jumpers, each alarm function can be site configured for high/low and Failsafe/Non-Failsafe relay action. This fast acting 50msec response time alarm, also comes standard with an adjustable deadband capability of 1-20%.
- Powers and Receives 4-20mA Signal from Airflow Sensor
- Dual field configurable alarms capable of alarming on
NAMUR failure output range from Airflow Sensor
- Relays rated 5A, 250VAC
- 50msec response time
- Adjustable deadband for each alarm