Installation of temperature and humidity sensors in explosive (Ex) environments

09-06-2021

We installed temperature and humidity sensors in the adhesives and chemicals warehouse.

In installations with elevated concentrations of explosive vapours and gases, the temperature and, where appropriate, the relative humidity must be measured by means of equipment specially designed to avoid the risk of explosion during operation. These devices must not generate high operating temperatures or sparks which could arise in the electrical circuit. Even a slight spark could cause ignition and explosion.

In our case it was a warehouse for adhesives and chemicals. The customer brought to our attention several non-standard requirements.

• Requires measurement of both temperature and relative humidity.
• The device must be designed for explosive atmospheres (Ex).
• The record of the measured values must be transmitted to the company Ethernet network.

Solution:

• For recording temperature and humidity we used an intrinsically safe sensor from Comet system s.r.o. T3110Ex with built-in temperature and humidity sensor. The sensor displays the measured values on the display and sends the measured data to the transmitter via a 4 - 20 mA current output. This transmitter is ATEX certified and therefore suitable for this purpose.
• A cable was run through the wall to the adjacent room where the wiring box was installed.
• The output from the transducer passed through a MM 7087+ zener barrier, which is suitable for current loops of 4 - 20 mAh.
• The P2520 web sensor then converted the 4 - 20 mA current loop to an Ethernet network.
• The customer can view the measured data on a computer or other device that is connected to the network. A web browser is sufficient or from ModbusTCP, SNMPv1, SOAP, XML.
• He can transfer the record to Comet Database or his own database using the above mentioned communication protocols.
• If internet access is provided, WebSensors can also transfer data to the COMET Cloud internet storage.