ANSI FL 1 - standard for measuring the performance of light fixtures

ANSI/NEMA FL 1-2009 is the full name of the recognized standard for measuring the performance of lighting fixtures. We are most interested in flashlights, both tactical and civilian, which need to be categorized and compared based on firmly defined criteria.

Classification according to this standard is crucial not only for pricing but also for how a given flashlight can assist you in specific situations in the field, making it a key element of your equipment.

The ANSI/NEMA FL 1-2009 standard was issued by the American National Standards Institute. The specific series of FL 1 standards is defined as Flashlight Basic Performance and was compiled by the Flashlight Standards Committee. Although these standards were intended for the American market, they have gradually become recognized worldwide, partly because no other such comprehensive set of standards existed elsewhere at the time.

Laboratory Conditions

There are naturally also amateur measuring devices that can measure light performance almost anywhere. However, "to be valid," the parameters (specifically see below) of handheld flashlights or headlamps must be measured under predefined laboratory conditions. Due to this, variations between individual flashlights caused by external influences can be minimal and essentially negligible. Therefore, ANSI FL 1 can be considered an objective source of information about the flashlight in question.

The laboratory conditions for the ANSI FL 1 standard are established as a controlled environment with a temperature of 21 °C (or a range from 18 °C to 24 °C) and relative humidity of 50 to 80%. It is under these working conditions that the specified parameters of flashlights are guaranteed.

What Parameters Are Measured

According to the ANSI/NEMA FL 1-2009 standard, the following parameters of flashlights are measured:

• luminous flux in lumens,
• beam intensity (in candelas)
• range,
• runtime on a single battery charge,
• impact resistance and water resistance.

Sometimes luminous intensity is incorrectly listed as a value in lumens. This misleading term can be found not only in flashlights but also in backlit displays of televisions or computer monitors.

How It Was Before

As the name of the standard suggests, it was created relatively recently, in 2009 (and came into practice approximately a year later). Until then, manufacturers measured the performance of their lighting devices in various ways. Nowadays, using the ANSI/NEMA FL 1 standard is not mandatory, but it is in the interest of every manufacturer to have the light performance of their flashlights measured according to this standard. This allows their products to be better and more objectively comparable to the competition – which ultimately is the mechanism that encourages progress and the effort to develop new products.

Previously, each manufacturer set their own method for measuring the performance of lighting fixtures. Performance was compared, for example, with candles (the intensity of light from one or two million candles), which was an inaccurate and misleading comparison. The brightness of one candle cannot be precisely defined because how do you define a single candle? It somewhat resembles the famous Cimrman phrase "a hundred thousand mice lined up in a row, ..."

There were also marketing gimmicks like "high luminous flux LED" which again says little. The number of watts of an LED light source was not indicative either, because each manufacturer naturally stated the highest possible performance under ideal conditions, to which the flashlight could realistically only rarely come close.

If any manufacturer initiated measuring the luminous flux itself before the introduction of the ANSI FL 1 standard, it was usually done without objectivity – even though it was not their fault. ANSI FL 1 deliberately deducts a certain reserve from the maximum luminous flux to account for losses incurred in the optical system of the flashlight, or possibly (although compared to classic bulbs only negligible) heating of the LED source. This reserve was generally not subtracted by manufacturers before 2010. However, they neither lied nor told the whole truth.

What Is Measured?

The individual parameters of ANSI/NEMA FL 1 standards have precisely specified procedures that laboratories must follow in testing flashlights. But what exactly is measured using these procedures?

Luminous Flux

Luminous flux (directly translated from the English "output" also "light output") is a value given in units called lumens, which indicates the total amount of emitted light energy. This figure is measured in a so-called integrating sphere, which is naturally calibrated and standardized, and the value of the luminous flux is read in the time interval from 30 to 120 seconds after the flashlight is turned on.

Beam Distance

Beam distance is defined by ANSI standards as the distance between the flashlight and the point at which the light beam has an illumination intensity of at least 0.25 lux. This value is close to the illumination intensity of moonlit landscape during a clear full moon.

Runtime on a Single Battery Charge

Runtime on a single battery charge is defined as the total amount of time that passes between the initial luminous flux value (calculated as half a minute after the flashlight is turned on with fully charged batteries) and the moment when the luminous flux value decreases to 10% of this initial value.

Water Resistance

Water resistance for flashlights is based on the standardized IP protection rating system. For flashlights, four ratings are used: IPX4 (resistance to water splashing from all directions), IPX6 (resistance to powerful water jets), IPX7 (resistance to short-term immersion in water up to one meter deep for up to 30 minutes), and IPX8 (ability for continuous immersion to a pre-defined depth for up to 4 hours).

Impact Resistance

Impact resistance is measured in meters and is typically gradaed in half-meter intervals (from one meter upwards). This parameter determines the height from which the device can fall onto a concrete surface and continue to function correctly. If the flashlight's impact resistance is less than one meter, this parameter is not specified.

Beam Intensity

Beam intensity, also known as luminous intensity in candelas, is the light intensity value in the center of the flashlight's beam. The candela is a unit of energy. This value is measured with a calibrated luxmeter by taking measurements at distances of 2, 10, and 30 meters.

Perceived Brightness

An interesting aspect is the concept of perceived brightness, which is not linear. This means that when the beam intensity of one flashlight is half that of another specific flashlight, it is not perceived as half. Respectively - if the intensity of one flashlight were to theoretically double on paper, the increase would be perceived as significantly less than 100%.

Shortcomings of ANSI FL 1 Standardization

Standardization ANSI FL 1 naturally has its shortcomings. These, for example, concern some not entirely objective results for runtime on a single battery charge. This is due to the use of different types of batteries, which behave differently over time (discharge). Battery voltage fluctuates, or rather decreases, and this often happens non-linearly. Therefore, the runtime value on a single battery charge should be considered as more of an estimate.

Another issue concerns impact resistance. While the external components of the flashlight may be resilient enough to stay together, even if it is dropped three times an hour for a whole week, the delicate electronics within the flashlight could naturally degrade slightly with each fall. Therefore, impact resistance should again be considered an estimation. Respectively, one should keep in mind that if a flashlight with a stated 1 m impact resistance is dropped from a meter onto concrete once a week, nothing is likely to happen. But it certainly should not become a regular occurrence.