Praxair TAFA 8200 Advanced HP/HVOF Gun
The Model 8200 gun, also referred to as a torch, has key benefits of a lower heat transfer to the substrate including less barrel loading & wear, less heat loss to the water, less heat generated for removal by dust collection systems, & less combustion by-products produced. The new Model 8200 gun sets a new standard in the HVOF market.
Benefits of the Model 8200 Torch:
The new Model 8200 Advanced HP/HVOF gun reduces the energy required to spray a pound of powder by approximately 20+%. This reduces fuel and oxygen consumption, permits the use of a smaller water chiller (25% smaller), and importantly, reduces heat input into the substrate.
- Fuel and oxygen consumption reduced by 33%.
Typical fuel consumption has been reduced from 6 gph to 4.2 gph (30% reduction) and typical oxygen consumption has been reduced from 2000 scfh to 1250 scfh (38% reduction). Assuming fuel cost is $4/gal and oxygen is $0.01/cf, this reduces the
- Heat generated to the ambient air has been reduced by 24%.
Under typical operating parameters, the heat generated and transferred to the ambient air for the Model 5220 Standard gun is approximately 570,000 Btu’s2. The new Model 8200 gun produces 24% less energy, 434,000 Btu3. This means that the dust collector capacity and fan size could be reduced, in most instances, from 10,000 cfm to 8,000 cfm (a potential cost savings of approximately $5500 / dust collector on new installations.
- Gun weight has been reduced by 14%.
Gunweight has been reduced from 9.5# (4.3 kg) with the 5220 gun to 8.3# (3.8 kg) with the 8200. In some simple applications, this might permit the use of smaller, less expensive robots and other manipulation. In these instances, the robot capacity could be reduced, from 16 to 10 kilograms (a cost savings of approximately $6500 / robot).
- 18% Shorter gun provides greater flexibility.
A shorter gun length (5220 with 4-inch barrel = 14 inches (356 mm), 8200 with 4-inch barrel = 11.5 inches (292 mm)) and overall smaller gun4 allows greater manipulation programming flexibility and also allows spraying in more restricted places.
- Lower environmental impact.
The 8200 gun’s improved fuel/oxygen mixing and injection design improves combustion characteristics and allows more complete burning of the liquid fuel. Combine this with the lower gas and fuel consumption, and this reduces the manufacturing process environmental impact such as the output of combustion by-products like carbon monoxide (CO).
The Model 8200 gun is interchangeable with the Model 5220.
Optional 3-Way Powder Splitting
Praxair Surface Technologies has introduced a unique 3-port powder feed system for the TAFA Model 5220 and 8200 HP/HVOF® guns. The new 3-way splitter and 3-port interconnectors allow a more balanced powder distribution to the powder injection ports. This allows for more consistent coating quality and reduced barrel wear. With the improved powder introduction into the flame, the overall target “spot” size on the coating substrate is reduced thus improving target efficiency.
3-Port Powder Injection System
This 3-port powder injection system reduces the powder buildup and wear in the barrel. This powder injection design allows for a more balanced and consistent introduction of powder into the supersonic gas stream with less powder near the edges of the flame. This leads to better target efficiency by having a more concentrated spray “spot” with slightly higher deposit efficiency. These benefits allow for longer run times, reduced barrel replacement and lowers maintenance shutdown requirements.
The Praxair Surface Technologies TAFA Model 5220 and 8200 guns are the heart of the JP-5000® and JP-8000TM HP/HVOF® systems. These elegantly simple and effective designs produce coatings of the highest qualities.
Of critical importance to both guns is powder injection into the flame at the Interconnector located at the low-pressure region after the converging/diverging combustion chamber nozzle. Proper powder distribution to the powder injection ports is important for minimizing barrel wear as well as producing consistent coating quality. In order for the Interconnector to perform properly, the powder must be supplied to the powder injector ports in as equal distribution as possible.
For a gun equipped with a 2-port Interconnector, the optimal way to achieve a 50/50 distribution of powder is to use two powder feeders supplying equal amounts of powder and carrier gas to each side of the gun. However, this is more expensive upfront because of the cost of the second powder feeder.
System Spray Setup
The typical system spray setup is a simple, and less expensive, use of a 2-port Interconnector on the gun, single powder feeder with a “T” powder splitter. Using this setup, powder distribution is theoretically supposed to be 50% to each powder injection port. However, the “T” splitter never gives a 50/50 powder split. It is usually a 60/40 or 70/30 split which, over time, is erratic.
Though this “T” splitting of the powder has worked extremely well throughout the years, this new option may work better for your application needs. With the 3-way powder splitting arrangement, powder distribution from a single feeder is intended to be divided 33/33/33. Even if this becomes unbalanced the amount of powder going to each injection port is more evenly distributed than what is achieved using a two way “T” splitter.
Additionally, having 3 separate powder streams flowing almost equal mass that intersect in the center of the flame not only reduces barrel wear, but can in some instances, eliminate or minimize barrel loading from fine particle sized or low melting powders.
Switching from a 2-way to 3-way powder split is easy, simply replace the Interconnector, powder splitter and tubing from the splitter to the gun. Then, while maintaining the same powder feed rate, adjust carrier gas flow higher to approximately 11.8 – 13.2 l/min (25 - 28 SCFH).