The first is IP rating. IP or "Ingress Protection" ratings are used to define a light fixture's level of sealing effectiveness against intrusion from foreign bodies, specifically dirt and moisture. In most industrial fixtures this rating ranges from IP65 to IP69 — with the higher the number indicating a higher level of ingress protection. As mentioned, new housing designs utilizing LED technology have led to more fixtures with higher IP capability. In most industrial settings you simply can't have a fixture with a rating too high.
Chemical resistance is another important and often overlooked factor to consider, especially in wet and hose down applications where chemicals are almost always present. Polycarbonate, due to its workability, cost, and general durability, is one of the most widely used materials for lenses. Although durable in many instances polycarbonate can be susceptible to stress cracking, crazing, and color change over time if certain chemicals (especially acid based) are present. If exposure to chemicals may be a factor, be sure to check compatibility with the manufacturer. Other separating factors of industrial LED fixtures are lifetime ratings and maintenance considerations. LED lifetime is generally a result of two constituents: quality of construction (heat dissipation) and quality of components. The ability to properly and efficiently remove the heat generated from individual LEDs will significantly increase the overall lifetime of the fixture. High quality fixtures that do just that are now typically rated up to 100,000 hours. Extended lifetimes result in less maintenance and greater payback over time. Other potential maintenance and installation cost reduction features to be on the lookout for include quick-connect cabling and the ability to daisy chain fixtures when making extended runs. With the potential for impactful energy savings and the development of fixtures suited for specific applications there has never been a better time to consider LED lighting in industrial environments.