Application Note: Control, data acquisition and calculation using your dataTaker equipment

Customer Requirement

A Sydney company required a controlledatmosphere environment as part of pilottesting of a new process. To reduce costs,existing equipment was used whereverpossible. The hostile atmosphere producedwas found to be incompatible with availablehumidity sensor technologies, requiring thesemeasurements to be derived in real time usingmeasurements from secondary sensors.

Equipment

• DT500 data logger
• DeLogger 4 Pro
• Dehumidifier
• Relays
• Peroxide Dispersal System
• Sensors: 4–20mA H₂O₂ Sensor ; RTD temperature sensors; Humidity measurement (calculated from wet and dry bulb temperatures)

dataTaker Solution

By using the programmable Alarm functions of the DT500 and its digital outputs, the DT500 ensures the initial atmosphere is adjusted to pre-set temperature and humidity levels. Alarms operate relays and solenoids interfaced to heating elements, a refrigerative dehumidifier and the dispersal system.

Programmed ‘interlocks’ (Alarms) ensure that each subsequent step is not started until its precursory conditions are met. Once these conditions are attained, the DT500 controls a relay which activates the dispersal system introducing the nebulised peroxide into the controlled atmosphere.

Conditions and levels are monitored and logged in internal memory. As mentioned, humidity cannot be directly measured, so the DT500 calculates this using known relationships from other measured atmospheric variables. During each trial the data is returned via serial connection to the PC running DeLogger 4 software for real time graphing as well as display on a user friendly mimic screen.

At the end of each run, data is unloaded to a Replay file for further analysis.