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LED Lighting and MIL Spec Compliance

Considering military sales for your LED lighting products – many elements are evaluated through the process.  This article provides some basic guidance but remember that some specific applications may include very specific evaluation methods.  Consider the discussion here – please contact us for your specific needs.

LED Lighting – A “HOT” Topic for Ships

BY STEVE FERGUSON

It is nearly impossible to enter a home improvement, department or general merchandise store without bumping into an array of options for household lighting using Light Emitting Diode (LED) technology. Why not, with the promise lifetime operation with greatly reduced consumption of electricity? Price per bulb is still a factor but that is dropping quickly so a investment cost versus operation cost review is becoming more favorable. Increasing, the light spectrum from LED sources is becoming very close to natural light, providing higher quality lighting.

Can’t Stand the Heat? Wasted heat from lighting puts additional demands on the power grid. The heat by-product from many lighting technologies causes added air conditioning demands and other heat removal methods, especially in confined spaces. LED technologies operating with greater efficiency help reduce the heat production, not only reducing direct electricity demand but also reducing the electrical demand associated with the added heat load. LEDs typically use 75% less energy than an equivalent incandescent (incandescent lighting release about 90% of their energy as heat, for compact fluorescent lights it’s about 80%) .One could go on and on about the benefits but core to this article is how adoption of this technology affects military ships. For many years, general lighting has been traditionally provided by fluorescent fixtures. The conversion from the traditional T8 and T12 styles requires a change in fixture or fitting the existing fixture with LED-based tubes.

Let’s consider some things that have generated a lot of interest in lighting conversion to LED technology.

  • Reducing heat load (more efficient operation reduces heat loads)
  • Reducing electrical consumption and fuel use to generate the electricity
  • Spare parts (longevity allows for fewer spare parts being required, less space, less weight, less loading/unloading, less activity in changing lights)
  • Weight (LED tubes are significantly lighter)
  • Retention of used tubes (mercury content of fluorescent tubes often meant keeping the used item until return from deployment for recycling. Recycling LED tubes may be accomplished but without the concern about hazardous materials)
  • LED lights are “solid state” devices and are less susceptible to the breakage of their gaseous cousins

There are estimates that the conversion on a large ship can remove 90,000 lbs (45 tons, or the weight of about three F-18s) from the ship’s physical load.

The US Navy has implemented a program to support the conversion and about every distributor of LED lighting considered bidding. Many soon encountered that the Navy had an established a qualification program to ensure reliability in the harsh shipboard environment. A couple of primary options were apparent: either build a complete fixture with embedded technology to replace existing fixtures or build LED tubes that fit the existing fixtures.

New fixtures seemed to be the obvious choice – get rid of the weight – which meant that lighter housings, no heavy ballast and using lightweight LED strips, presented the greatest benefit. One downside exists: an LED means replacing the complete fixture, unless the LED array allowed exchange at the array level. Also, the initial cost for complete upgrade could be a bit higher.

Building LED tubes that fit existing fixtures has generated a large interest because of the ease in conversion and continuing maintenance, ie., dealing with a disposable component instead of replacing a fixture. Most tube technologies call for bypassing the ballast in a text fixture. Note that tube recovery and rework with a new LED strip allows for a reduction of waste and separation of parts and supports recycling of most of the plastic materials. These are important environmental considerations, especially when on extended deployment.)

Standard For Lighting MIL-DTL-16377J Once the qualification requirements were understood, many suppliers realized that, as distributors, controlling manufacturing quality adequately to meet the obligations was too difficult and several dropped out of the bidding. MIL-DTL-16377J (SH) (with Supplement 1 and Notice 1) issued June 2014 provides the detail specification for lighting fixtures and associated parts. Supporting this specification standard, many (slant or /) standards dealing with specific lighting applications were in existence and many needed updates to include this technology (solid state lighting (SSL) as part of the options. This topic is quite broad, so we will focus this discussion to MIL-DTL-16377/86A(SH), which addresses vital lighting by replacing fluorescent tubes.

The /86A standard (Feb 2015 is current) has been updated recently to resolve questions and clarify many of the evaluation requirements. I suspect that more updates are to follow to allow alternate methods to demonstrate acceptability. Three variants of tubes are listed in the /86A standard (12 & 35W, 1.5 & 1 inch diameter, 24”& 457/8” lengths).

The standard provides a table of first article test and inspection requirements that apply to the tube to confirm acceptability. I like to categorize the list to organize the general nature of the test and evaluation program and report content, as indicated in the table below. The table identifies the particular requirement paragraphs of MIL-DTL-16377J and there you may encounter reference to other standards. There are a few critical details the may be overlooked, in our experience with these programs indicates.

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