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TEC Sales is proud to announce Steve Lytle has joined our team as a partner/business development.
Steve has over 20 years in the Electrical Industry. He has a diverse successful work history in Sales and Sales Management positions covering small and large Electrical Distributors, as an Electrical Manufactures’ Representative, and Senior Level Management with National and International Electrical Manufactures.
Steve has lived in Spring, Texas with his wife and three children for the last 13 years. Over the past Eleven years Steve was the Area Manager for Rexel Houston, helping them grow into the number one location in the world out of 2600 branches. His most recent position was with R.STAHL Inc. As their Chief Sales and Operational Officer for the past eight years, He provided the Sales and Operational leadership to help them grow into one of the world leaders in Hazardous location electrical and automation interface products and system solution manufactures.
Steve prides himself on helping others become successful. He continues to build strong industry relationships through his Christian beliefs, and leadership ability to become others’ trusted advisor. Please welcome Steve to our team.
Installing an enclosure cooling solution for a water or wastewater treatment plant will protect valuable electrical equipment and prevent the breakdown of critical operations.
Here are the answers to 10 Frequently Asked Questions about enclosure cooling systems and their use in water treatment facilities.
1. Why does a water treatment plant need an enclosure cooling system?
Electrical equipment used to operate water treatment facilities must be protected from excess heat. Components such as programmable logic controllers (PLCs), transformers, and variable frequency drives (VFDs) which are housed in electrical enclosures will begin to suffer in performance, reliability, and lifespan if they remain above their maximum allowable temperature for too long.
Choosing the right enclosure cooling solution, sizing it correctly, and maintaining it properly, will ultimately save money, reduce downtime, protect the environment, and ensure the safety and purity of the water exiting the plant.
2. What conditions must an enclosure cooling system located in a water treatment plant be able to withstand?
The cooling system must be shielded from the harsh conditions commonly found in these locations, due to corrosion and/or contaminants. For example, many enclosure air conditioners utilize aluminum filters that are not built to withstand the chlorine cleaning chemicals sprayed on enclosures in wastewater treatment plants.
3. What NEMA type should be used for a water treatment plant enclosure?
The National Electrical Manufacturers Association (NEMA) has specified different ratings for protective electrical cabinets, based on the environment in which they are located. Enclosure cooling systems fitted to these cabinets should have the same NEMA type rating.
Because of the harsh conditions often found in and around water and wastewater treatment plants, electrical enclosures for these locations should typically meet the NEMA 4X standard.
NEMA 4X is specified for indoor or outdoor use, providing protection from extreme weather and climate, and exposure to dust and corrosive materials. This type of enclosure is also watertight and designed to tolerate the high-pressure spray that occurs during the cleaning process.
NEMA 4X is the ideal electrical enclosure type for applications that are subject to corrosion and wash-down with cleaning solutions, or other sterilizing chemicals, and where high pressure cleaning equipment is utilized.
Enclosures with a NEMA 4X rating are especially suitable for use in hot, humid environments, such as found in Florida, and in coastal marine environments—a typical location for desalination plants—where equipment may be exposed to salt water and the corrosion rates of mild steel equipment are high.
4. What are the requirements for a NEMA 4X enclosure?
Though enclosures with a NEMA 4X rating are sometimes referred to as waterproof, this is not strictly correct because a NEMA 4X enclosure cannot be submerged in water. However, it should be water tight, and should not allow water to accumulate in places where mold could grow. Additionally, all NEMA 4X enclosures must be dustproof and resistant to damage caused by the formation of ice.
The NEMA 4X rating also specifies that the enclosure will meet minimum conditions of corrosion resistance, though they may not necessarily protect the enclosure completely in actual site conditions where long-term exposure to corrosive vapors, such as chlorine and other chemicals used for sterilizing water/wastewater treatment facilities, is present.
5. What type of cooling system meets the NEMA 4X requirements?
Once the NEMA type for an enclosure has been determined, an enclosure cooling system can be selected from one of two basic types: open loop or closed loop. An open-loop cooling system is one that allows ambient air to circulate through the enclosure, for example with a forced air fan.
A closed loop cooling system is one in which air inside the electrical enclosure has no direct contact with outside air. Rather than blowing air into it, a closed-loop system removes heat from the air inside the enclosure and transfers it to the air outside. This insures that the enclosure is not contaminated with ambient air, dirt, chemicals, dust, moisture or foreign matter so that sensitive components are protected and are kept at the required operating temperature.
NEMA 4X enclosures must be sealed to prevent contaminants, corrosive gases, solids, or liquids, from reaching the electric components within. For this reason, closed loop cooling systems are required for these enclosures.
6. What types of closed loop cooling systems are available for water treatment plant enclosures?
Two basic types of closed loop cooling systems are air conditioners and air to air heat exchangers. Both have benefits and drawbacks to be considered when selecting a cooling system for a water or wastewater treatment plant enclosure.
In the case of an air conditioner, hot air from the electrical enclosure is drawn out, passed through an evaporator coil that cools it, and is then returned to the enclosure without ever encountering the outside air. The same method is used in the case of an air to air heat exchanger, except the heated enclosure air is passed over the evaporator side of a heat pipe.
7. Which type of closed loop cooling system is right for a water treatment plant enclosure?
A heat exchanger can only approach the same temperature inside the enclosure as it is outside, so if the ambient temperature is higher than the maximum allowable temperature for the components, it will not protect them from excess heat. In that case, an enclosure air conditioner is the only choice for maintaining a safe temperature inside the enclosure.
An enclosure air conditioner represents an extremely effective method of cooling an enclosure and will work efficiently even if the ambient temperature is much higher than the enclosure’s air temperature. It will also control humidity much better than a heat exchanger, which may be important for sensitive electrical components.
8. How should an enclosure cooling system for a water treatment plant be selected and sized?
Selecting a properly sized cooling system is critical for optimal operation and maximum efficiency. Specifying too large a system will result in higher costs than necessary, and may adversely affect the operation and efficiency of the system. A system that doesn’t have enough cooling capacity, however, will impact the reliability and lifetime of the electrical components.
An online Enclosure Temperature Management (ETM) calculator can simplify the process of selecting and sizing an enclosure cooling system. The calculator gathers information about a specific application and then calculates the cooling capacity of a suitable air conditioner or heat exchanger.
An ETM calculator takes into account metrics such as:
· Enclosure dimensions
· Desired temperature
· Ambient temperature
· Heat load
· Enclosure material
· Enclosure color
· Location of the unit
9. What are some options available to protect an enclosure cooling system in a water treatment plant from corrosion and contaminants?
Although not mandatory, NEMA 4X enclosures are generally manufactured from stainless steel as this provides the ideal substrate to resist the corrosion and weathering tests required to achieve the NEMA rating. If the enclosure will be located in a marine environment, 316 stainless steel is preferable to 304 stainless steel, due to its increased corrosion resistance.
Some manufacturers offer optional stainless steel air filters to help the enclosure withstand chlorine exposure. It’s also important to ensure that any exposed copper refrigeration tubing is protected with a corrosion resistant coating to prevent premature failure.
10. Where can I get assistance in selecting an enclosure cooling system for a water treatment plant?
Thermal Edge works with wastewater treatment facilities and many other types of industries to provide enclosure air conditioners that are both reliable and efficient. We also offer a suite of options and accessories, including corrosion protection and specialized filters, to ensure the best protection of your valuable electrical equipment.
For more information and help selecting and sizing an enclosure cooling system for a water treatment facility, contact Thermal Edge today.
It is generally accepted that industrial control panels need some form of enclosure cooling to ensure that internal temperatures do not exceed equipment-safe working limits. In most instances, the heat load is such that the panel needs to be, at the very least, fitted with cooling fans. However, due to a desire to prevent equipment becoming contaminated by dirt and dust, closed loop solutions are often specified. Here’s how to assess the right cooling solution.
The Purpose of Enclosure Cooling
In the absence of forced cooling, the rate of heat dissipation from an enclosure is low. The internal temperature will rise until a thermal equilibrium is reached where the rate of heat generation is equal to the rate of heat dissipation through the walls and vents as a result of convection and conduction.
A review of the maximum recommended operating temperatures of control panel equipment shows that while some devices can tolerate temperatures as high as 140 °F, a significant proportion can only reliably operate at temperatures that do not exceed 104 °F.
The purpose of enclosure cooling is to increase the rate of heat removal to keep the internal enclosure temperature below 104 °F. For safety’s sake, it is recommended that industrial control temperatures should be kept at or below 95 °F.
How to Assess Industrial Control Panel Cooling Requirements
The internal temperature of an electrical enclosure is directly related to the heat load inside the enclosure, the ambient temperature and the rate of heat removal. These may be assessed as follows:
Internal heat load:
The first step is to assess the heat load of the equipment installed inside the enclosure. Itemize all pieces of equipment, and ascertain how much heat they generate. For items such as relays and contactors, the heat generated is approximately equal to their coil wattage. Similarly, the heat loss of a PLC can be derived from the power consumption of its power supply. For thermal devices like thermal magnetic breakers, the power loss can be obtained from technical documentation.
The calculation of the heat generated by variable frequency drives (VFD), rectifiers and inverters is slightly more complex because it depends on the efficiency of the device at its operating current. As an illustration, a 10 kW VFD with an efficiency of 90 percent will generate 1 kW of waste heat. The total internal heat load is the summation of the heat loss of each item of equipment.
If a control panel is installed so that it’s exposed to the sun or to heat radiation from nearby equipment, this must be factored into the calculation. Take note of the extent of solar radiation, the color of the panel, its materials of construction and if it has insulation.
Determine the maximum expected ambient temperature as this will represent the worst case scenario. If using climate data, don’t use the average maximum temperatures as these are always lower than the highest temperatures that are expected.
Although the simplest cooling solution is to ventilate the enclosure, this is not always possible because of high ambient temperatures or the presence of excessive dirt, dust, pollution or even driving rain or water sprays. If any of these conditions exist, closed loop cooling will be required. This means that the enclosure should be completely sealed and cooled using an air conditioner or air to air heat exchanger.
Calculating Enclosure Cooling Requirements
Although it is possible to calculate the enclosure cooling requirements manually, the calculation is complex, and unless appropriate factors are known and understood, significant errors are possible. A more effective method is an online enclosure temperature management (ETM) calculator that incorporates the appropriate factors.
Using the calculator is simple once all the necessary information is entered, and it’s easy to compare the three alternative cooling solutions and choose the one that’s most suitable. The cheapest solution is filtered fans. This is ideal if the environment is clean and the ambient temperature is lower than the allowed cabinet temperature. If there’s a need to seal the cabinet and use closed loop cooling an air to air heat exchanger provides similar cooling capacity to filtered fans — although like fans, the ambient temperature must be lower than the enclosure temperature. For those locations where ambient temperatures exceed the enclosure temperature, the only option is an enclosure air conditioner that, due to its refrigeration ability, can bring the internal temperature down below ambient temperature.
Air to air heat exchangers are an ideal solution for cooling electrical enclosures—when used correctly. What is the right way to use an air to air heat exchanger? Here are some tips.
Replace filtered fans that don’t cool enough
When components are failing inside electrical enclosures that rely on filtered fans for cooling, it’s time to consider a more powerful cooling solution.
As electrical components have decreased in size and increased in number and power, equipment inside electrical enclosures has become more tightly packed. These components are more likely to be exposed to waste heat caused by operating inefficiencies. The cooling capacity of a filtered fan may not be adequate for removing this heat, along with any additional heat from insolation, and/or nearby sources, such as ovens and boilers.
Air to air heat exchangers remove heat using a process similar to mechanical air conditioning, but without the compressor. Instead, they use a “heat pipe,” a sealed copper tube which contains liquid refrigerant under a partial vacuum. The lower section of the tube is in contact with heated air from the electrical enclosure. When the heat hits the refrigerant inside the tube, it vaporizes and then flashes to the top of the pipe, which is in contact with air from outside the enclosure.
Because the outside air temperature is lower than the enclosure temperature, the refrigerant vapor gives up heat to the air and returns to the liquid phase. The liquid falls to the bottom of the pipe, repeating the cycle endlessly, so long as there is a negative temperature differential between the outside air and the enclosure.
Protect electrical equipment from contaminants
No matter how well a filtered fan may cool an enclosure, or how well the filter blocks out contaminants, it will not be able to prevent every bit of dirt, dust, moisture, and chemical fumes from getting inside. Electronic equipment such as variable frequency drives (VFDs) and PLCs do not operate well in the presence of these contaminants.
Unlike a filtered fan system, an air to air heat exchanger operates as a “closed loop” system with no exposure to outside air. A baffle at the midpoint of the heat pipe coil, provides an airtight seal between the two air systems. In this way the air inside the enclosure is separated from–and is not contaminated with–ambient air, dirt, chemicals, dust, moisture or foreign matter. As a result, sensitive enclosure components are protected and are kept at the required operating temperature.
Specify the correct size
Because the heat pipe relies on a temperature differential, the ambient air temperature must be cooler than the enclosure operating temperature for it to work. This means an air to air heat exchanger can only be used in situations where the ambient temperature is lower than the desired enclosure temperature. The greater the temperature difference, the greater the quantity of heat that can be removed by the heat exchanger.
When sized properly, a heat exchanger will provide cooling to a temperature slightly higher than the ambient temperature. The delicate electronics, for example in programmable logic controllers (PLCs) may have maximum operating temperatures not far above room temperature. The operating temperature should be 10 to 20 degrees higher than the maximum ambient temperature.
A large heat exchanger removes 40 watts per degree Fahrenheit. So, assuming a temperature difference of 20 °F, the total quantity of heat that it can remove is 800 watts or 2,730 BTU/hr. (Use this online Enclosure Temperature Management Calculator for help in calculating the correct size of an air to air heat exchanger for your application.)
Choose the right options
Air to air heat exchangers come in a range of NEMA types to suit different applications. Typically, heat exchangers are used for NEMA Types 12, 4, and 4X, because they require a closed-loop cooling system sealed against outside air.
Once the correct cooling capacity and NEMA type have been determined, several other options are available to accommodate individual set-ups. For example, a corrosion protection package may be specified to provide coatings on metallic parts that could be damaged in the presence of corrosive chemicals or vapors.
For hazardous industrial sites such as refineries, the ambient may contain flammable gasses, vapors or flammable liquids. Using a closed-loop cooling system, such as an air-to-air heat exchanger, with a Hazardous Location designation helps protect the valuable electrical components from these hazards.
Hazardous Location units are available which conform with all requirements of UL and CUL for Class 1, Division 2, Groups A, B, C and D, and Temperature Code T6.
Though filtered fan systems will save money upfront, in the long run air to air heat exchangers may cut the cost of cooling an electrical enclosure. Heat exchangers can be the most efficient method of cooling, as the excess heat is the engine which drives the system. In addition, an air to air heat exchanger will protect valuable components from excess heat, as well as from harmful contaminants, contributing to fewer repairs over time and an overall longer equipment life span. The only power requirement is to operate two air circulating fans.
For more information about selecting and sizing an air to air heat exchanger enclosure cooling system, contact the experts at Thermal Edge.
The selection of an enclosure air conditioner is relatively simple provided you pay attention to the details and correctly size the unit. Proper selection is important because an air conditioner that’s too large will cycle frequently, causing relatively wide temperature fluctuations that contribute to thermal stresses. In addition, the frequent cycling could reduce the service life of the compressor by as much as 50 percent. Conversely, if the air conditioner is too small, there’s a serious risk that the enclosure temperature will get too high, potentially causing equipment damage and reduced life.
These guidelines will help you select the right air conditioner enclosure for any application.
Establish Environmental and Ambient Conditions
As a first step, identify exactly where the enclosure will be placed. Then establish the ambient temperature range in that location. Be sure to correctly identify the maximum ambient temperature. If the unit is outdoors,obtain climate data from local authorities and look at historical maximum temperature records. take note of weather extremes and note if dust or dirt is a problem and whether any corrosive chemicals are present. Record the maximum humidity and obtain records for the dew point at that location.
Determine the optimum enclosure temperature. This should be somewhat lower than the lowest maximum equipment temperature specified in manufacturers’ catalogs. Remember that equipment life is shorter at high temperatures, so choose a moderate temperature. A temperature of 95 °F is generally considered to be a good compromise between cooling requirements and equipment life.
Identify the Total Heat Load
Calculate the total heat load of the equipment inside the enclosure. Information is available from manufacturers’ catalogs and data sheets. You can use the device power consumption as a starting point. The heat loss can be calculated by multiplying power consumption by the inefficiency of the device. For example, if a device is 90 percent efficient, 10 percent of the power consumed is converted into heat.
If the enclosure is outdoors, take note of whether it’s shaded or in direct sunlight. Also note if it has insulation, its materials of construction and color.
Determine Enclosure NEMA Rating
Enclosure air conditioners work on a closed loop cycle in a sealed enclosure, so make sure there are no openings or ventilators. Ideally, the enclosure should have a minimum NEMA rating of 12. If it’s outdoors, subject to water sprays or high levels of dust it’s likely to require a NEMA 4 rating, although a NEMA 4X is often specified. NEMA Type 4X enclosures are also required in locations subject to corrosive liquids or vapors. The enclosure air conditioner must have the same NEMA type rating as the electrical enclosure.
Identify Any Special Requirements
Identify any special requirements that may affect enclosure cooling. These may include situations where you need to monitor and manage the temperature of a specific item of equipment. This can be achieved using a remote temperature probe. Other points to look for are the positions of the air inlets and outlets to ensure that equipment will not block the airflow and any constraints that may restrict where the air conditioner enclosure is mounted.
Calculate Capacity of the Air Conditioner
The required air conditioner capacity is calculated using the total enclosure heat load, ambient temperature and the required internal temperature, while taking into account the effects of solar radiation, enclosure finish and insulation. Although it’s possible to perform the calculation manually, it’s easier and often more accurate to use a specialized online Enclosure Temperature Management calculator.
Using the result determined by the calculator, select an air conditioner model that is the next size up. Don’t go smaller as there’s a risk the unit will not have sufficient capacity in hot weather.
There are various air conditioner models available with different profiles, so choose a model that suits the width of your enclosure, taking special note of the location of the air inlet and outlet to ensure that the air flow is not restricted. Select a unit with an appropriate supply voltage and the correct NEMA type rating.
Identify any options that are required, and include the heater package if there’s a risk of condensation in cool weather. Don’t forget to consider other options such as the facility tomonitor the air conditioner remotely. If you need help or assistance, speak to our Sales Teambefore finalizing your choice.