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PollutionEngineering November 2012 : Page 37

Advertorial S BETE FOG NOZZLE HOWTO: Factors that Infl uence the Nozzle Material Selection Process Sometimes, selecting the right nozzle material can be simple. Other times, it can be very complex and confusing. Depending on how harsh (or mild) the environment is in any given process, determining the right material for a nozzle may be as easy as matching an installed material that has proven to high pH environments. Corrosion and erosion are material related. Chemical attack causes corrosion while suspended solid particles abrading the surface lead to erosion. There is a very wide range of materials from which a nozzle can be made; proper selection of the nozzle material will minimize corrosion and ero-sion problems. Erosion. Abrasive wear, or erosion, can cause the nozzle to wear out pre-maturely, leading to increased flow and degraded spray formation. This leads to increased process fluid costs and unacceptable process quality. Hardened stainless steel, Cobalt Alloy 6, tungsten carbide, and ceramics are commonly used in applications where abrasive fluids are sprayed. Weight. There are times when mini-mizing structural weight is an impor-tant consideration. A nozzle made from a strong yet lightweight material such as titanium can be the perfect answer. Initial Cost vs. Total Cost. There are exceptions, but materials can generally be ranked in the following order in terms of cost (from lowest to highest): brass, carbon steel, plastics, stainless steels, cobalt-base alloys, nickel-base alloys, ceramics, refrac-tory metals and precious metals. Beyond the initial cost of a nozzle, it is extremely important to consider the long-term costs of having a nozzle in a material not suited for the application. How much do the operating costs increase due to frequent shutdowns for nozzle replacement? What is the cost impact to a poor quality product or process due to a spray nozzle that wears out too quickly and performs poorly? Once the right material is determined, BETE can supply your nozzle no matter how exotic or routine that material may be. BETE uses three basic manufactur-ing processes: injection molding, CNC machining and investment casting. weather the conditions just fine. Other times, there are factors that can lead to confusion about which material is best. Temperature. Melting or softening of material establishes maximum temperature limits. However, these temperature limits must be reduced when corrosion, oxidation, or chemical attack are also present. Corrosion. Material performance and reliability varies with exposure to differ-ent chemical types and concentrations. It is important to consider the properties of the environment where the nozzle is installed and the properties of the fluid spraying through the nozzle. Plastics offer superior corrosion resistance at relatively low cost, but can only be used in low-temperature applications. In general, met-als can be ranked in the following order of corrosion resistance (from lowest to high-est): carbon steel, brass, stainless steels, nickel-based alloys, refractory metals and precious metals. Ceramics have excel-lent corrosion resistance except in very Injection molding is used for large quanti-ties of nozzles made from plastics such as PVC, ABS and PVDF. CNC machining is often used for metal alloy and plastic noz-zles that have relatively small quantities. Investment casting at our in-house foundry offers the flexibility to produce complex shapes in common or specialty alloys that provide a unique performance advantage to our customers. Having a foundry on our premises in Greenfield, Massachusetts means that we have total control of production quality and sched-ule at every step. BETE Fog Nozzle T (413) 772-0846 NOVEMBER 2012 37

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