Like most labels used to classify luminaires, “vapor tight” encompasses a wide range of fixtures with often-subtle differences that can greatly impact appropriate applications. For the general consumer, these differences mean little on paper but can be the difference between a successful lighting upgrade and hours of filling out warranty claim paperwork.
Housing Material
Advances in material science are leading to more material blends in fixture housings, but most vapor tight housings are still made from one of two materials: fiberglass or polycarbonate.
The classic vapor tight (think fluorescent tubes inside an enclosure) pairs a fiberglass housing with either a polycarbonate or acrylic lens. Fiberglass offers superior chemical and UV resistance for demanding applications. If you walk into a poultry barn, wastewater facility, or food processing plant and look up, these are the vapor tights you’re most likely to see.
As lighting manufacturers searched for more cost-effective materials and processes to produce vapor tight housings, many turned to polycarbonate and injection molding. In addition to being more cost effective at volume, injection molded polycarbonate vapor tight housings are lighter and often offer greater impact resistance than fiberglass. These factors make polycarbonate the housing material choice for practically all imported vapor tights. If you’ve ever bought a vapor tight from your local Lowe’s or Home Depot, chances are it had a polycarbonate housing.
Each of these materials excels in different areas, which is why many manufacturers offer both. Working on a budget and just concerned with your fixture surviving a wet location? A polycarbonate fixture is a great option. Outfitting a barn, food processing, or manufacturing facility? Check the spec sheet and make sure you are choosing a fixture with a fiberglass housing.
| Material | Fiberglass | Polycarbonate |
|---|---|---|
| Impact Resistance | Good – can crack under sharp impact | Excellent – great for high-abuse areas |
| Chemical Resistance | Excellent – one of its strongest features | Okay – ammonia, cleaners, and degreasers can lead to stress cracking |
| Heat | Excellent – won’t soften or deform | Good – softens at 125-135°C |
| UV Resistance | Excellent – holds up outdoors for years | Good – can yellow over time |
Gasket
Despite giving vapor tight luminaires their water-and-dust proof characteristic, gaskets rarely get more than a line on a spec sheet. Instead, gasket quality is implied by the IP ratings (we’ll discuss these later) listed on a spec. Not all gaskets are the same, and understanding materials and installation methods ensures that your vapor tight performs to spec.
When fixture specs do mention a gasket, the material listed is almost always either polyurethane or silicone. Looking back at the classic vapor tight build, polyurethane was the gasket material of choice. Housings were designed to last decades while fluorescent tubes needed to be replaced every few years. Polyurethane’s strength against abrasion and tears meant that repeated opening of the fixture to replace tubes did not lead to gasket failure. Like polycarbonate housings, silicone has risen as a popular gasket material choice following the advent of LED. Silicone provides many of the benefits of polyurethane but is not as abrasion or tear resistant. What silicone lacks in tear resistance, it makes up for with excellent performance in extreme cold and hot environments (-55°C to 200°C).
Arguably the most important consideration when choosing a gasket is how the manufacturer installs it. Classic vapor tights use pour-in-place to dispense polyurethane foam into a channel on the fixture housing. This method sets the gasket in place and prevents the contractors from having to position or reposition the gasket during install. Pour-in-place is not limited to polyurethane, either. Silicone gaskets can also be installed this way. The other common manufacturer installation method uses a rope or die-cut gasket with an adhesive backer to set the gasket in place. Though popular, this does create two potential headaches: a frustrated installer who has to reposition a gasket that comes unstuck when a lens is removed, or a frustrated purchaser who has to fill out warranty paperwork when a fixture is full of water because that frustrated installer did not reposition the gasket properly.
Though cliché, “a chain is only as strong as its weakest link” often holds true. Gaskets are a small part of a vapor tight design but are the difference between fixtures that are watertight and those that end up looking like fishbowls.
IP Rating
Talking IP Ratings immediately after gaskets may seem a bit redundant, so we won’t go too far into the weeds here (for an IP testing and ratings deep dive you can check out this guide).
There is really only one question you need to ask to determine whether a “standard” vapor tight is sufficient for your project: Will the fixtures be sprayed/washed down? For fixtures going in a parking garage, under a canopy, or inside a warehouse, an IP65 rating will typically get the job done. Livestock barns, food processing facilities, or car washes are much more demanding and are better served by fixtures with an IP66 rating for spray or IP69 fixtures for washdown.
If you’re in the electrical industry, you probably wouldn’t have to look very hard to find someone with a horror story of a non-washdown-rated vapor tight that stepped into the ring with a pressure washer. Those fights never make it past the first round.
Other Things to Consider
Rather than a paragraph for each of these, below is a list of other things to consider before selecting a vapor tight.
- Mounting – Surface mount, chain-hang, pendant? See what accessories are included versus optional.
- Lens – Did you choose a fiberglass housing for its UV and chemical resistance? Make sure you are pairing that with an acrylic lens and not polycarbonate.
- Thru-Wiring – Is the housing set up for thru-wiring or is someone going to have to drill holes on the jobsite?
- NSF – Make sure you see an NSF logo on the spec sheet for any fixtures you plan to buy for food and beverage processing.
- CRI – Inspection tables or color-critical work? Check to see if the manufacturer offers 90+ CRI as an option.
Final Thoughts
An online search for “vapor tight LED fixture” returns page after page of similar looking luminaires from manufacturers’ websites and online retailers like Walmart and Amazon. Sift through several spec sheets and you’ll find a lot of similar language: wet-location, IP rated, watertight. This guide is meant to make finding the differences easier – small things to skim for that determine appropriate fixture application.
Interested in a full deep-dive into the world of vapor tights? Or, have a fixture application you need help with? Reach out – I’m always available to talk about your next lighting project!