A company from the Middle East contacted me about cooling a gas sampling device that was placed inside an enclosure. The Middle East is well-known for Oil and Gas and hot ambient temperatures. The sampling system was used by a Petroleum company to measure the composition of gas samples. This type of device had a refrigerant system to keep the sample at a predetermined temperature. Since the ambient conditions were very high, they noticed incorrect readings with their calibration gas. They wanted to use an enclosure to protect the instrument from the environment and to use the Vortex technology to cool the surroundings of the gas sampling instrument to help it work properly.
Like with any A/C unit, the higher ambient temperatures will reduce the cooling capacity of a refrigeration system. The customer gave some details of what they needed. They wanted to target an internal temperature at a maximum of 35oC (95oF) which would allow for proper readings. The enclosure measured 2000 mm X 1200 mm X 1000 mm (79” X 47” X 39”), and it was made from 316SS with insulation inside. The area was classified as a Class 1 – Div2 which means that there is a potential for an explosive gas to be present. The sampling machine generated about 170 watts (580 BTU/hr) of heat inside. The maximum ambient temperature was 50oC, and the instrument grade air that was being used for the Cabinet Cooler was only at 6 bar (87 PSIG). With all this information, I had a lot to consider to determine the correct cooling capacity.
The first thing that I needed to decide was if they had a purge system on the hazardous panel. They sent a diagram setup of the panel as shown below. They did have a Z-purge system as reference as #4 in the diagram. (This was the correct type of purge system for a Div2 area). They also showed a check valve on the cold air side to reduce the potential risk for ingress. With the design of the EXAIR HazLoc Cabinet Coolers, we use a poppet valve to keep any dangerous liquids or gases from entering. So, they could remove it from their item list which saved them money.
With the calculation for the total heat load, I recommended the model HZ4840SS-316-240. When they installed the EXAIR system to their enclosure; they were extremely happy with the compact size and the ease of installation. Now, when a sample bottle came in for test, they were able to attach it to the gas sampler and allow for the Z-Purge system to evacuate the enclosure. Once the purge system cycled, the solenoid valve for the Cabinet Cooler as well as the gas sampling system started operating. With the instant cold from the HazLoc Cabinet Cooler, the gas sampling equipment was able to find the composition of the gas accurately and consistently.
The EXAIR HazLoc Cabinet Cooler Systems are designed to keep your electrical panels cool within hazardous areas like the Class I – Div 2 above. The certification is under UL Classified for Class I, Class II, and Class III areas with both Div1 and Div2. System shutdowns from electrical components overheating or incorrect measurements with gas sample analysis are costly and potentially dangerous. If you would like to discuss in more details about the different types of EXAIR HazLoc Cabinet Coolers, an Application Engineer at EXAIR will be happy to help you.
John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb