Gas powder coating oven is used to cure powder coatings onto metal surfaces. They use natural gas or propane to generate heat, and they can typically reach temperatures of up to 400 degrees Fahrenheit.
Gas powder coating ovens are more energy-efficient than electric powder coating ovens, but they do produce emissions. It is important to properly ventilate the work area to remove these emissions.
Gas powder coating ovens are typically equipped with a number of safety features, including:
- Emergency stop button
- Overheating protection
- Fire suppression system
- Ventilation system
- Interlocking doors
These safety features help to protect workers, equipment, and the environment from potential hazards.
Safety guidelines for operating a gas powder coating oven:
- Wear appropriate personal protective equipment (PPE), such as gloves, safety glasses, a respirator, and long sleeves and pants.
- Make sure the oven is properly ventilated to remove fumes and dust.
- Ground the oven to prevent electrical shock.
- Do not overload the oven.
- Inspect the oven regularly for damage or wear and tear.
- Have a fire extinguisher nearby.
Additional safety tips:
- Never operate a gas powder coating oven in an enclosed space.
- Keep flammable materials away from the oven.
- Be aware of the signs of a fire, such as smoke, heat, and flames. If you see or smell any of these signs, evacuate the area and call the fire department.
- Train your employees on the safe operation of the oven.
By following these safety guidelines, you can help to prevent accidents and injuries.
Gas Powder Coating Oven
Gas powder coating ovens typically use gas as a fuel source for the heating process in powder coating applications. Powder coating is a method of applying a protective and decorative finish to a wide range of materials, including metals and certain plastics.
Here’s a breakdown of how a gas powder coating oven might work:
- Preparation of the Object: Before powder coating, the object to be coated is cleaned and prepared. This often involves removing any existing coatings, oils, or contaminants.
- Application of Powder: The powder coating material is applied to the object electrostatically. This creates a uniform coating on the surface.
- Curing Process in the Oven: After the powder is applied, the object is moved to the curing oven. This is where the gas heating system comes into play. Gas-fired ovens are commonly used for their efficiency and cost-effectiveness.
- Heating and Curing: The oven is heated using gas burners. The heat causes the powder to melt and flow into a uniform coating. The curing process typically involves maintaining a specific temperature for a set period, allowing the coating to chemically cross-link and form a durable finish.
- Cooling: After the curing process is complete, the object is allowed to cool. The finished product is a durable, high-quality coating that is resistant to various environmental factors.
Gas ovens are popular in powder coating applications due to their ability to provide consistent and controlled heating. They are also relatively cost-effective compared to some alternative heating methods.
Gas oven:
A gas oven is a type of powder coating oven that uses natural gas or propane as a fuel source to heat the curing chamber. Gas ovens are typically more energy-efficient than electric ovens, and they can heat up more quickly. However, gas ovens can also produce more emissions, so it is important to ensure that they are properly ventilated.
Convection oven:
A convection oven is a type of gas powder coating oven that uses fans to circulate hot air throughout the curing chamber. This helps to ensure that the temperature is uniform throughout the chamber, which is important for curing the powder coating evenly. Convection ovens are typically more efficient than radiant ovens, and they can also cure parts more quickly.
Radiant oven:
A radiant oven is a type of gas powder coating oven that uses infrared radiation to heat the curing chamber. Infrared radiation can penetrate the powder coating and heat the substrate directly, which can help to cure the powder coating more quickly than other types of ovens. However, radiant ovens can also create hot spots, so it is important to use them with caution.
Infrared oven:
An infrared oven is a type of radiant oven that uses infrared emitters to generate infrared radiation. Infrared emitters can be gas-fired or electric. Gas-fired infrared emitters are typically more efficient than electric infrared emitters, but they can also produce more emissions.
Curing zone:
The curing zone is the part of the gas powder coating oven where the powder coating is cured. The curing zone is typically heated to a temperature of 150-200 degrees Celsius (300-390 degrees Fahrenheit) for a period of 10-30 minutes.
Cooling zone:
The cooling zone is the part of the gas powder coating oven where the parts are cooled after they have been cured. The cooling zone is typically not heated, but it may have fans to help circulate air and cool the parts more quickly.
Temperature control:
Temperature control is important for gas powder coating ovens because the curing process is temperature-sensitive. If the temperature is too low, the powder coating will not cure properly. If the temperature is too high, the parts may warp or crack.
Uniformity:
Uniformity is important for gas powder coating ovens because it ensures that all parts are exposed to the same temperature and time profile. This helps to prevent variations in the quality of the cured powder coating.
Efficiency:
Efficiency is important for gas powder coating ovens because it helps to reduce costs and energy consumption. Efficient ovens use less energy to cure the powder coating and they can process more parts per hour.
Energy consumption:
Energy consumption is an important consideration for gas powder coating ovens because they can be energy-intensive. Efficient ovens use less energy to cure the powder coating, which helps to reduce environmental impact.
How to use a gas powder coating oven
Here is how a gas powder coating oven operates:
- The parts to be coated are prepared. This involves cleaning and degreasing the parts to ensure that the powder coating will adhere properly.
- The powder coating is applied to the parts. This can be done using a variety of methods, including electrostatic spraying, fluidized bed dipping, or manual dipping.
- The parts are placed in the gas powder coating oven. The oven is heated to a specific temperature, which is typically between 350 and 400 degrees Fahrenheit.
- The powder coating melts and flows over the parts, forming a smooth, continuous film. The curing process typically takes 10 to 20 minutes, depending on the type of powder coating and the desired finish.
- Once the powder coating has cured, the parts are removed from the oven. The parts are now coated with a durable, long-lasting powder coating finish.
Gas powder coating ovens are a versatile and efficient way to apply powder coatings to a wide variety of parts. They are used in a wide range of industries, including automotive, aerospace, appliance, and furniture manufacturing.
Here are some safety guidelines for operating a gas powder coating oven:
- Always wear appropriate personal protective equipment (PPE), such as gloves, safety glasses, a respirator, and long sleeves and pants.
- Make sure the oven is properly ventilated to remove fumes and dust.
- Ground the oven to prevent electrical shock.
- Do not overload the oven.
- Inspect the oven regularly for damage or wear and tear.
- Have a fire extinguisher nearby.
Gas powder coating ovens are a versatile and efficient way to cure powder coatings. By following the safety guidelines and operating instructions, you can ensure that your gas powder coating oven is safe and effective.
Powder coating of metals is often favored by manufacturers because its finish is tougher than conventional paint. Powder coating is abrasion resistant and will not crack, chip, or peel as conventional paint will. Powder coating is typically done through a two-step process:
First, the coating is applied to the part electrostatically with powder coating equipment, and then the newly powdered part is cured in an industrial gas powder coating oven under heat to form a skin.
This process is very efficient since the powder wraps around the back of the part for better coverage and ensures 95% material usage of the powder. The powder coating is a dust-like substance that behaves quasi-fluid. with the help of this material property, the powder coating flows through the hoses and gun of powder coating equipment and reaches the part already ionized with – ion.
This helps the particle hang on the part and stay there till the part is grounded again. The parts that are coated with powder are either manually, or automatically with the help of a conveyor taken into the gas oven, which inside there is a 200 C temperature to melt the powder coating on the parts
Benefits of powder coating and curing in an oven: Heavy-duty construction and quality components Excellent uniformity and heating rates for consistent, high-quality curing results No powder blow-off – reduces rework Uniform heat distribution provides quality cured finishes and optimum cure cycles Quick heat-up rates so you can cure more loads per day Roof-mounted blowers conserve valuable floor space at your facility Fully adjusted and factory tested prior to shipment to reduce installation and start-up times Available with our exclusive energy-efficient oven upgrade
Environmental impact:
Gas powder coating ovens can have an environmental impact due to the emissions they produce. These emissions can include carbon dioxide, nitrogen oxides, and volatile organic compounds (VOCs). However, gas powder coating ovens are typically more energy-efficient than electric ovens, which can help to reduce their overall environmental impact.
Safety:
Safety is an important consideration for gas powder coating ovens because they use natural gas or propane, which are flammable fuels. It is important to ensure that gas powder coating ovens are properly installed and ventilated to prevent the risk of fire or explosion. Operators should also be trained on how to operate the ovens safely.
Maintenance:
Regular maintenance is important for gas powder coating ovens to ensure that they are operating safely and efficiently. Maintenance tasks include cleaning the ovens, checking the burners and ignition systems, and calibrating the temperature controls.
Airflow:
Airflow is important for gas powder coating ovens because it helps to distribute heat evenly throughout the curing chamber and to remove fumes and VOCs. Proper airflow can help to prevent the buildup of hot spots and the emission of harmful pollutants.
Heat distribution:
Heat distribution is important for gas powder coating ovens because it ensures that all parts are cured evenly. If the heat is not distributed evenly, some parts may not be cured properly, while others may be damaged.
Insulation:
Insulation is important for gas powder coating ovens because it helps to trap heat and improve energy efficiency. Proper insulation can help to reduce the amount of heat that is lost from the curing chamber, which can save energy and reduce costs.
Construction materials:
The construction materials used to build gas powder coating ovens should be durable and able to withstand the high temperatures and harsh conditions of the curing process. Common construction materials include steel, aluminum, and stainless steel.
Size:
The size of a gas powder coating oven is an important consideration because it determines the number of parts that can be cured at the same time. The size of the oven should be based on the production needs of the facility.
Capacity:
The capacity of a gas powder coating oven is the maximum number of parts that can be cured at the same time. The capacity of the oven should be based on the production needs of the facility.
Loading and unloading:
The loading and unloading of parts into and out of a gas powder coating oven should be done safely and efficiently. Proper loading and unloading procedures can help to prevent injuries and reduce downtime.
The Parts to be Coated are Prepared
Degreasing is the process of removing dirt, oil, and grease from the parts. This is important to ensure that the powder coating will adhere properly. Degreasing can be done using a variety of methods, including solvent cleaning, vapor degreasing, and alkaline cleaning.
Sanding is the process of removing any rust or corrosion from the parts. It can also be used to create a rougher surface, which will help the powder coating to adhere better. Sanding can be done using a variety of tools, including hand sanders, power sanders, and blast cabinets.
Once the parts have been degreased and sanded, they are ready to be powder coated.
The Powder Coating is Applied to the Parts
There are three main methods for applying powder coating to parts:
- Electrostatic spray: This is the most common method of applying powder coating. The powder is charged electrostatically and then sprayed onto the grounded part. The electrostatic charge attracts the powder to the part, resulting in a uniform coating.
- Fluidized bed dipping: The parts are dipped into a fluidized bed of powder coating. The fluidized bed is a tank of powder that has been agitated to create a fluid-like state. When the part is dipped into the fluidized bed, the powder coats the part evenly.
- Manual dipping: The parts are manually dipped into a vat of powder coating. This method is less common than electrostatic spray and fluidized bed dipping, but it can be used for small parts or complex shapes.
Once the powder coating has been applied, the parts are placed in a gas powder coating oven to cure the powder coating. The curing process melts the powder coating and flows it over the parts, forming a smooth, continuous film.
The choice of application method will depend on the size and shape of the parts, the type of powder coating being used, and the desired finish quality.
The Parts are Placed in the Gas Powder Coating Oven
Once the powder coating has been applied, the parts are placed in a gas powder coating oven to cure the powder coating. The curing process melts the powder coating and flows it over the parts, forming a smooth, continuous film.
The parts are typically placed on racks or hangers and loaded into the oven. The oven door is then closed and the oven is heated to the specified curing temperature. The curing time will vary depending on the type of powder coating and the desired finish quality.
Once the curing process is complete, the oven door is opened and the parts are removed. The parts are now coated with a durable, long-lasting powder coating finish.
Here are some safety guidelines for loading and unloading parts from a gas powder coating oven:
- Wear appropriate personal protective equipment (PPE), such as gloves, safety glasses, and a respirator.
- Be careful not to overload the oven. Overloading the oven can restrict airflow and increase the risk of fire.
- Allow the parts to cool completely before handling them.
- Use caution when removing the parts from the oven, as they may be hot.
By following these safety guidelines, you can help to ensure that the process of loading and unloading parts from a gas powder coating oven is safe and efficient.
The Powder Coating Melts and Flows Over the Parts, Forming a Smooth, Continuous Film
Yes, the powder coating melts and flows over the parts, forming a smooth, continuous film. Here is an image of the powder coating melting and flowing over the parts:
The melting and flowing of the powder coating is an important part of the curing process. During the curing process, the powder coating particles melt and fuse together to form a solid film. This film is what protects the parts from corrosion and other damage.
The melting and flowing of the powder coating is also important for achieving a high-quality finish. The smooth, continuous film that is created by the melting and flowing of the powder coating gives the parts a uniform appearance and protects them from scratches and other blemishes.
Here are some factors that can affect the melting and flowing of the powder coating:
- Type of powder coating: Different types of powder coatings have different melting points and flow characteristics.
- Curing temperature: The curing temperature must be high enough to melt the powder coating particles, but not so high that it causes the powder coating to overheat and decompose.
- Curing time: The curing time must be long enough to allow the powder coating particles to melt and fuse together completely.
- Airflow: Proper airflow in the oven is important for ensuring that the powder coating particles are heated evenly and that the powder coating cures properly.
By carefully controlling the type of powder coating, curing temperature, curing time, and airflow, manufacturers can ensure that the powder coating melts and flows properly, resulting in a high-quality finish.
Once the Powder Coating has Cured, the Parts are Removed from the Oven
Once the powder coating has cured, the parts are removed from the oven. Here is an image of parts being removed from a gas powder coating oven:
The parts are typically removed from the oven using racks or hangers. It is important to allow the parts to cool completely before handling them, as they may be hot.
Here are some safety guidelines for removing parts from a gas powder coating oven:
- Wear appropriate personal protective equipment (PPE), such as gloves, safety glasses, and a respirator.
- Be careful not to overload the racks or hangers. Overloading the racks or hangers can cause them to collapse, which could damage the parts or injure workers.
- Allow the parts to cool completely before handling them.
- Use caution when removing the parts from the oven, as they may be hot.
By following these safety guidelines, you can help to ensure that the process of removing parts from a gas powder coating oven is safe and efficient.
Small Gas Powder Coating Oven
The dimensions of our small powder coating oven start from 1,2m x 1,2m x 1,2m. This is for lab powder coating applications. The lab-type oven is used to cure powder coating for samples and small items in a small number
Powder coating companies that are doing custom coating can have some special requests for small items and samples. They don’t want to heat up a big oven for this and require a small lab-type box oven.
This small oven can also be used for powder coating at home. Some people try to make their own DIY powder coating oven but this usually takes a long time for construction and can have some serious mistakes in manufacturing that can cause inefficiency and even danger to human life.
The powder coating cost usually increases in such DIY powder coating oven types. If the curing won’t be effective, you will need to use a powder coat remover to get the powder off the powder-coated metal has the entire powder coating process once again. The powder coating prices are not that low to let you repeat the same process again and again.
Gas Powder Coating Oven Characteristics
Temperature Controller
An Electronic Temperature Controller controls temperature conditions. It is a non-profiling type 1/16 DIN single channel controller that features automatic control. Either a time proportioned heat output or a 4-20 ma control signal is used for precise temperature control
Overtemperature Protection
An Electronic Temperature Controller is provided for temperature protection. The Electronic Temperature Controller will remove power to the heating system when an over-temperature condition is detected. Alarm circuitry may be included as an option.
Process Timer
A Process Timer is provided, which has five user-selectable timing ranges from 0.01 seconds to 9999 hours. The timer will automatically start timing once the process setpoint temperature is reached. When the total preset time has elapsed, power to the heat control circuitry will be disabled.
Additional Features
EMS Powder Coating Equipment ovens are designed with the capability to incorporate many other optional features for safety purposes, enhanced process control, and a simplified operator interface. Consult a Gruenberg Applications Engineer or our Service Department for more information or questions.
Operating Parameters and Requirements
This equipment is designed to operate safely when the following environmental conditions are met:
- Indoor use only.
- Within a temperature range of 5°C to 90°C (max).
- Maximum relative humidity 90%.
The listed chamber specifications are based on operation at 24° C ambient temperature, the altitude at sea level, and a 60 Hz power supply. Chamber operation utilizing a 50 Hz power supply may derate the listed performance specifications. Equipment damage, personal injury, or death may result if this equipment is operated or maintained by untrained personnel.
Operators and service personnel must be familiar with the location and function of all controls and the inherent dangers of the equipment before operating or maintaining it. TPS shall not be liable for any damages, including incidental and/or consequential damages, regardless of the legal theory asserted, including negligence and/or strict liability.
Observe all safety warnings and operating parameters listed in this manual, as well as all Caution, Danger, and Warning signs or labels mounted on the equipment to reduce the risk of equipment damage and personal injury.
Automation:
Automation can be incorporated into gas powder coating ovens to improve efficiency, consistency, and safety. Automated systems can handle tasks such as loading and unloading parts, controlling temperature and curing times, and monitoring oven performance. This can help to reduce operator error, improve product quality, and minimize the risk of accidents.
Monitoring:
Monitoring systems can be used to track the performance of gas powder coating ovens and identify potential problems. These systems can monitor temperature, airflow, and other critical parameters to ensure that the ovens are operating safely and efficiently. Alarms can be triggered to alert operators to potential problems, allowing them to take corrective action before a problem occurs.
Data logging:
Data logging systems can be used to collect and record data from gas powder coating ovens. This data can be used to track oven performance over time, identify trends, and troubleshoot problems. Data logging can also be used to create reports for quality control and regulatory compliance purposes.
Troubleshooting:
Troubleshooting is the process of identifying and resolving problems with gas powder coating ovens. Common troubleshooting tasks include checking burners and ignition systems, calibrating temperature controls, and addressing airflow issues. Operators should be trained on how to troubleshoot common problems with the ovens they operate.
Types of gas powder coating ovens:
There are several different types of gas powder coating ovens available, each with its own advantages and disadvantages. The most common types of gas powder coating ovens include:
- Convection ovens: Convection ovens use fans to circulate hot air throughout the curing chamber, ensuring even heat distribution.
- Radiant ovens: Radiant ovens use infrared radiation to heat the curing chamber, which can cure parts more quickly than convection ovens.
- Infrared ovens: Infrared ovens use infrared emitters to generate infrared radiation. Infrared emitters can be gas-fired or electric.
Applications of gas powder coating ovens:
Gas powder coating ovens are used in a wide variety of applications, including:
- Automotive manufacturing: Gas powder coating ovens are used to coat car parts, such as bumpers, wheels, and frames.
- Appliance manufacturing: Gas powder coating ovens are used to coat appliances, such as refrigerators, stoves, and washers.
- Industrial manufacturing: Gas powder coating ovens are used to coat industrial equipment, such as machinery, tools, and parts.
Benefits of using gas powder coating ovens:
There are several benefits to using gas powder coating ovens, including:
- Energy efficiency: Gas powder coating ovens are typically more energy-efficient than electric ovens.
- Faster curing times: Gas powder coating ovens can cure parts more quickly than electric ovens.
- Uniform coating: Gas powder coating ovens can provide a more uniform coating than wet paint applications.
Limitations of gas powder coating ovens:
There are also some limitations to using gas powder coating ovens, including:
- Emissions: Gas powder coating ovens can produce emissions, such as carbon dioxide, nitrogen oxides, and VOCs.
- Safety: Gas powder coating ovens use flammable fuels, so it is important to ensure that they are properly installed and ventilated.
- Cost: Gas powder coating ovens can be more expensive than electric ovens.
Safety considerations for gas powder coating ovens:
There are several safety considerations for gas powder coating ovens, including:
- Proper installation and ventilation: Gas powder coating ovens should be installed and ventilated by a qualified technician.
- Training: Operators should be trained on how to operate gas powder coating ovens safely.
- Fire protection: Gas powder coating ovens should be equipped with fire suppression systems.
- Personal protective equipment (PPE): Operators should wear appropriate PPE, such as gloves, safety glasses, and respirators, when operating gas powder coating ovens.
Maintenance tips for gas powder coating ovens:
To ensure that gas powder coating ovens are operating safely and efficiently, it is important to perform regular maintenance. Maintenance tasks include:
- Cleaning: Regularly clean the ovens to remove dust, debris, and overspray.
- Inspection: Inspect the ovens regularly for signs of wear and damage.
- Calibration: Calibrate the temperature controls regularly.
- Servicing: Have the ovens serviced by a qualified technician annually.
Selecting the appropriate gas powder coating oven for your specific needs is crucial for achieving efficient and high-quality powder coating results. Here’s a comprehensive guide to assist you in making an informed decision:
- Assess Your Production Needs:
- Determine the size and volume of parts you intend to coat.
- Consider the desired curing times and production throughput.
- Evaluate the type of powder coating materials you’ll be using.
- Evaluate Oven Types and Features:
- Convection ovens offer even heat distribution and are suitable for a wide range of parts.
- Radiant ovens provide faster curing times and are ideal for heat-sensitive materials.
- Infrared ovens offer targeted heating and can be energy-efficient.
- Consider Energy Efficiency and Emissions:
- Gas powder coating ovens are generally more energy-efficient than electric ovens.
- Choose an oven with efficient burners and insulation to reduce energy consumption.
- Implement proper ventilation systems to minimize emissions.
- Safety and Ergonomics:
- Ensure the oven complies with safety standards and has proper fire suppression systems.
- Choose an oven with easy loading and unloading mechanisms to minimize operator strain.
- Provide adequate training and personal protective equipment for operators.
- Cost and ROI:
- Obtain quotes from leading gas powder coating oven manufacturers.
- Factor in installation, maintenance, and operational costs.
- Calculate the return on investment (ROI) to justify the purchase.
Leading Gas Powder Coating Oven Manufacturers:
- Dürr Systems
- Eisenmann
- Gema
- Reliant Finishing Systems
- Sprayshop Equipment USA
Gas Powder Coating Oven Resources:
- Powder Coating Institute (PCI)
- North American Association for Powder Coating (NAPCO)
- American Coating Association (ACA)
- Powder Coating Research Institute (PCRI)
Gas Powder Coating Oven Safety Data Sheets (SDS):
- Obtain SDS for the specific powder coating materials you’ll be using.
- Understand the potential hazards and handling precautions for each material.
- Implement proper storage, handling, and disposal procedures.
Gas Powder Coating Oven Installation Manuals:
- Follow the manufacturer’s installation manual precisely for safe and proper setup.
- Ensure the oven is installed in a well-ventilated area away from flammable materials.
- Connect electrical and gas connections according to local codes and standards.
Gas Powder Coating Oven Troubleshooting Guides:
- Familiarize yourself with common troubleshooting procedures for the specific oven model.
- Identify potential troubleshooting scenarios and their corresponding solutions.
- Contact the manufacturer’s technical support for assistance if necessary.
Gas Powder Coating Oven FAQs:
- Consult FAQs provided by manufacturers or industry resources to address common questions.
- Find answers to frequently asked questions about oven selection, operation, maintenance, and safety.
- Stay informed about latest advancements and best practices in powder coating technology.
Gas Powder Coating Oven Glossary:
- Understand the terminology used in gas powder coating ovens and related processes.
- Familiarize yourself with key terms such as curing zone, airflow, insulation, safety interlocks, and VOCs.
- Effectively communicate and collaborate with colleagues and suppliers using industry-standard terminology.
Location and Installation of the Gas Powder Coating Oven
- Oven Classification – Electric Heated Units: NFPA 86 Class B ovens are heat utilization equipment operating at approximately atmospheric pressure wherein there are no flammable volatiles or combustible material being heated in the oven.
- Oven Classification – Gas Heated Units: NFPA 86 Class A: “Class A ovens and furnaces are heat utilization equipment operating at approximately atmospheric pressure wherein there is a potential explosion or fire hazard that could be occasioned by the presence of flammable volatiles or combustible materials processed or heated in the furnace.”
- Do not locate units in areas of wide ambient temperature variation such as near vents or outdoor entrances.
- Do not place the unit near combustible materials or hazardous fumes or vapors.
- Do not install the unit in a corrosive environment. A corrosive environment may lead to poor performance and deterioration of the unit.
- Ventilation: The oven should be installed in an area where there is good air ventilation. Allow a minimum of 5 inches between any wall and any oven side.
- Do not position the oven in a manner that would make it difficult to operate your main power disconnect switch.
- Make sure the oven is leveled when set up. The floor of the chamber should be leveled with a Spirit Level to +/- 1/8” (3.175 mm) front to back and side to side.
- Sometimes control panels are removed to facilitate shipment. When required, replace the panel securely and reconnect numbered electrical wires to matching numbered terminal blocks.
Very Important! Upon completion of the initial installation of the chamber and upon completion of any maintenance procedure, make sure that all access panels that have been removed are reinstalled securely before operating the unit.
Exhaust Connection for Gas Powder Coating Oven
An exhaust port connection consisting of a 6” O.D. collar is installed with the exhaust blower assembly at the top of the oven. The exhaust housing includes a manual damper. A vent duct should be connected to the exhaust port collar and run to a location outside of the building (as necessary). This should be done in accordance with all local code regulations. Make sure the connection is secure.
Gas Supply Connection for Gas Powder Coating Oven
Gas-fired ovens may use either natural gas or liquid propane for combustion to heat the oven. You must follow your specific supply specifications listed on your General Arrangement Drawing D001 and when listed here.
Important! Please read the entire Gas Heating System section and all vendor manuals / cut sheets to familiarize yourself with all gas components before making your gas supply connection. The gas supply connection is made to a ball valve with a ½” FPT type connection. Make sure the connection is secure and is checked for leaks before operation.
Gas Supply – Liquid Propane: Pressure = xxx PSIG, xxxx CFH
Gas Supply – Natural Gas: Pressure = xxx PSIG, xxxx CFH
Air Circulation of Gas Powder Coating Oven
Gas-fired heating systems are normally installed in walk-in modular ovens. A high-volume airflow system is employed to provide maximum temperature uniformity. The type of air circulation system used depends on the configuration of the unit.
Single module units can only employ a horizontal front-to-back airflow type pattern using centrifugal type blower wheels to generate air circulation. Double module units can employ two different types of air circulation systems, as listed below.
- Horizontal front-to-back pattern using centrifugal type blower wheels.
- Compound horizontal pattern using propeller-type fans.
The heating and generation of airflow occur in the conditioning plenum, which is normally located on the right side wall of the oven.
Blower wheels or fans are driven with extended shafts by motors mounted in the control cabinet. Heating is achieved by a gas burner that directs a flame down into a vertical perforated flame tube mounted in the manifold next to the conditioning plenum. Thermocouples used for temperature sensing are normally mounted in the workspace on the plenum panel.
Airflow Description
Gas ovens using centrifugal type blower wheels for airflow generation employ a horizontal front-to-back type airflow system. The burner manifold is designed with a vertically mounted flame tube along with perforations on the back side of the manifold. Processed air is drawn into the burner manifold and conditioning plenum, and is heated as it mixes with hot air emitted from the flame tube.
Fresh ambient air is also drawn into the plenum where it mixes with the heated air. Conditioned air is discharged into the workspace through perforations near the front of the plenum housing. The air flows back through the workspace in a horizontal manner to condition the product and then returns to the plenum for reconditioning.
A portion of the processed air is exhausted through a port in the chamber ceiling by the exhaust blower. An air intake port with a manual slide damper is installed in the ceiling of each module to allow fresh ambient air to replenish the exhausted air. Slide dampers are mechanically locked to a predetermined minimum opening.
Heating System of Gas Powder Coating Oven
Important Note: Due to the diverse array of configurations available in a gas heating system, this section will describe basic system requirements, standard equipment used, and fundamental operation.
EMS Powder Coating gas heated ovens are designed to operate with either a natural gas supply or a liquid propane supply according to NFPA 86 (National Fire Protection Association) safety standards. To meet NFPA main gas train requirements, a Closed Position Indicator CPI is used for electrical indication of the safety valve’s closed position. A direct-fired type gas system is used in which the flame is shot through a burner manifold in the conditioning plenum.
Recirculating oven air is heated as it is drawn through the flame. Direct-fired systems are typically greater than 90% efficient. Since products of combustion enter the workspace with this type, it is reserved for those processes that are not emission sensitive.
However, many safety precautions are employed with a direct-fired system to compensate for the presence of an open flame. The following sections detail the standard gas heating components used and their operation. The actual components used will vary with your application, so it’s important to check your oven specifications.
Exhaust Blower of the Gas Powder Coating Oven
An exhaust blower is standard with all direct-fired systems to serve two purposes. Initially, the blower is used along with a purge air timer to purge oven air for a fixed time before the gas burner is fired.
When the purge cycle time is complete, the exhaust blower is used to maintain a constant exchange of oven air with fresh ambient air. Ambient air is drawn into the oven through slide dampers mounted atop each module.
A differential pressure switch is used to monitor airflow generation by the exhaust blower, and subsequently for the correct operation of the blower motor. These devices use a diaphragm to sense pressure and to mechanically trigger an SPDT Snap Switch when the proper pressure is developed across the blower wheel (or fan).
Correct rotation of the motor is necessary for the switch to operate properly. If a loss of pressure/airflow were detected, the switch would open and remove power from the gas burner.
Loss of airflow may result from a motor malfunction, a loose blower wheel (or fan), or constricted air intake or exhaust ports. Blower Spark-Proof Design: The blower housing is designed with a non-sparking type construction. The housing and inlet rings are made of aluminum while the blower wheel is made of stainless steel. Should the blower wheel come off its shaft and strike the blower housing or inlet ring, no sparks can be generated between the two metals.
Oven Exhaust Issues
Gas convection cure ovens and some dry-off ovens are exhausted to remove raw fuel, byproducts of combustion, and any emissions from the coating materials. The coating materials may include compounds that are emitted by design, as well as decomposition byproducts from fallen powder or parts.
By necessity, ovens designed to cure conventional solvent-borne coatings must have much higher exhaust rates to remove hazardous solvents from the oven and work atmosphere. The removal of combustion byproducts is critically important to prevent the yellowing or darkening of light colors. General guidelines for powder cure ovens are:
- Three air turnovers per hour for non-appearance parts.
- Four to Six air turnovers per hour for dark colors.
- Six to Eight air turnovers per hour for clear coatings.
- Eight to Twelve air turnovers per hour for light colors and appearance parts.
Certain situations may require higher exhaust rates: - Curing solvent-borne or Ecoat in the same oven with powder. The
byproducts of these can interfere with powder cure or produce yellowing in light colors. - Curing multiple powder chemistries in the same oven environment can
produce gloss reduction and even wrinkling in a smooth coating. - Combination cure and dry-off ovens. High exhaust rates required to remove water vapor.
- Contaminated makeup air (plant air) is used rather than fresh outside air. The number of air turns in an oven is the rate at which fresh air replaces the initial air volume by the oven blower. The exhaust requirements can vary greatly with oven design.
Indirect burners represent far less of a problem with combustion gases than direct-fired burners. The air turns for direct-fired ovens should be higher. If the oven is exhausted over a period of time contaminants such as nitrous oxides and sulfur dioxide may build up to produce a condition known as a fouled oven.
In these cases, some coaters place buckets of liquid Ammonium Hydroxide or solid Ammonium Salts at the oven exit and entrance at shutdown to assist in neutralizing these acidic materials. Additionally, cleaning and servicing the burners may be necessary. The formula for determining Oven turns is:
Oven Turns = Make-up air exchange Rate/Oven Volume
Oven Residue
Many powder coating ovens have an oven fuzz that builds up in and around the cool zones such as the vestibule at the oven opening and around the exhaust fan. This material is generally made up of:
- Low molecular weight resins
- Flattening agents
- Blocking agents
- Degassing agents
- Decomposition products from the resin
The cause of build-up is generally caused by poor oven design or poor maintenance. This oven residue should be cleaned out by vacuuming or washing with a power spray washer.
Other factors which may contribute are: - The frequent line stops with a full load in the oven.
- Excessive oven temperatures
- Uneven heat in the oven results in hot and cool zones. This can result
from baffling, the placement of a cooling tunnel or poor insulation on the exterior facing walls.
Hazards associated with these residues are:
- Flammability
- Inhalation by workers
- Contamination of the finished part.
Note, even though not all residues represent fire hazards they should be treated as such.
Gas Burner – Combustion Blower
The three elements necessary for combustion are fuel, oxygen, and ignition. The combustion blower supplies a constant flow of fresh air to the burner. The air is mixed with gas by various methods in order to establish ignition and to sustain complete combustion. The combustion motor starts immediately when the OVEN ON switch is closed. A combustion airflow switch monitors airflow from the combustion blower. This is a differential air pressure type, which will shut down the burner if a loss of airflow is detected.
A burner is defined as a device used for the introduction of fuel and air into an oven at the required velocities, turbulence, and concentration to maintain ignition and combustion of fuel. A Blast type burner is normally
used. This burner delivers a combustible mixture under pressure, normally above 0.3 inch W.C. to the combustion zone. Various flame safety devices are installed within the burner.
Not only do we manufacture our powder coating equipment, we also ship them worldwide to your facility with care
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