Hazardous Locations are a tricky opponent for electrical panels and controls. To safely be in a HAZLOC they either have to be rated for that Environment or they need to be enclosed in a Cabinet that is purged and pressurized to keep any explosive gases, fumes, or dusts out of the Cabinet.
This is no new thing, however as the Industrial revolution 4.0 continues to grow and progress products are continually being added to HAZLOC areas. For example, robotic controls, analyzers, motors and switch gears now use electronic accessories to meet the needs for, speed, process control and energy efficiency, which often renders the equipment unsuitable for use in hazardous locations.
While the demand for these new devices continues to grow, not all of these items are able to be made intrinsically safe. And the items that are not will need to be enclosed in a cabinet where heat will build and you need to manage that heat load while retaining the positive pressure a purge and pressurization is putting on the panel.EXAIR HazLoc Cabinet Cooler Systems are rated for Class I Div 1 & 2, Class II Div 1 & 2, and Class III environments.
First, we need to know what Class, Division, Group and Temp Code your area falls in.
Area Classification Methods
The NFPA (National Fire Protection Association) establishes area classifications using three factors. Identified as Classes, Groups and Divisions, these factors are combined to define conditions of specific areas.
Class Ratings – Classes are used to define the explosive or ignitable substances that are present in the atmosphere.
Class I – Flammable gases or liquid vapor.
Class II – Ignitable metal, carbon or organic dusts.
Class III – Ignitable fibrous materials.
Division Ratings – Divisions are used to define the degree of hazard by determining the explosive or ignitable substance’s expected concentration in the atmosphere.
Division 1 – Contains substances under normal conditions
Division 2 – Contains substances under abnormal conditions
Group Ratings – Groups are used to define substances by rating their explosive or ignitable nature, in relation to other known substances.
TYPICAL CLASS I SUBSTANCESGroup A – Acetylene
Group B – Hydrogen or > 30% Hydrogen by Volume
Group C – Ethyl Ether & Ethylene
Group D – Acetone, Ammonia, Benzene & Gasoline
TYPICAL CLASS II SUBSTANCESGroup E – Aluminum, Magnesium & Alloys
Group F – Carbon, Coke & Coal
Group G – Flour, Grain, Wood, Plastic & Chemicals
Temperature Class – A Temperature Class is a term that is allocated within a hazardous area or zone to instruments and equipment. The classification or rating signifies the levels of thermal energy allowed in a particular area or produced by specific equipment. EXAIR products are Able to be used in locations at or lower than T3C.
EXAIR Cabinet Cooler Systems are available, from stock, to suit most any electric/electronic panel heat protection need:
Cooling capacities from 275 to 5,600 Btu/hr. Call me if your heat load is outside this range…we can look at customized solutions too.
When choosing products for use in classified areas, it’s critical to ensure safety through compliance, and the HazLoc Cabinet Cooler Systems allow you to do that, with simplicity and reliability. If you’d like to discuss an enclosure cooling application, in or out of a classified area, give us a call.
Jordan Shouse
Application Engineer
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Here is a question; what is an eductor? Eductors are also called ejectors, Venturi jets, aspirators, jet mixers, or jet pumps. Eductors use either compressed gas or liquid to generate a vacuum by a Venturi effect which is based on Bernoulli’s equation. (You can read more about the person here, “People of Interest: Giovanni Battista Venturi March 15, 1746 – April 24, 1822 By Tyler Daniel”.) They can be used for vessel evacuation, gas sampling, pump priming, venting, and blending. EXAIR Line Vacs work on this same principle in creating a Venturi vacuum by using compressed gas. In this blog, I will cover the design, verification, and testing that EXAIR provided for a customer’s special.
For this customer, the design was based around our 2” and 1” 316SS Line Vacs. They required ISO flanges on the vacuum and exhaust sides to match their piping connections for gas sampling. They would supply nitrogen to the inlet port as a carrier gas to generate the venturi and to mix with the sample gas. Since the accuracy of the test is dependent on the amount of each gas, we had to test the operations of the Line Vacs at different conditions.
First, EXAIR designed these special Line Vacs to get approval. Once the customer approved, EXAIR had to make a strong effort to meet the other criteria that was requested. Generally, with our standard Line Vacs, we use our test data with estimated conveyance rates, inlet flow rates, and vacuum pressures measured at 80 PSIG (5.5 bar). For these special Line Vacs, we had to do a bit more work because it was for gas sampling. This was not a problem for us. EXAIR has many calibrated instruments to accurately measure different conditions. For this customer, we had to measure the inlet flow, suction pressure, velocity, and maximum back pressure at different inlet pressures. We also had to create another chart showing the exhaust velocities with a back pressure present.
From these details, the customer could calculate the amount of nitrogen that would be introduced to the gas sample at different pressures and backpressures. And, as an added preference, they requested us to do a leak check after assembly. We were willing to buy the flange blanks and add this test procedure to the router. We looked for leaks between the cap and body of the special Line Vac, as well as the flanges to verify that gas was not escaping. EXAIR tries to support our customers to the best of our abilities. For this customer, we worked together to provide the needed information for their setup.
The reason that I wrote this blog was to show that EXAIR has the capabilities to make special items for specific applications. If we need to use different materials, design configurations, and even present test data, we can decide the best course of action. With special products, they are unique to customers in fit, form and function as a solution, whether for end-users or OEMs. For the special Line Vac above, we presented the data as related to an eductor for this customer’s decision to place the order. If you would like to see if EXAIR can make a special product for you, please do not hesitate in contacting an Application Engineer at EXAIR. We will be happy to work with you.
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.
