- 1). Understand the different types of sodium vapor light fixtures. Low pressure sodium lights contain sodium vapor only, while high pressure fixtures contain sodium mixed with mercury under high pressure.
- 2). Determine what color light each fixture emits. Different light fixtures can emit light over various portions of the light spectrum, which can dramatically impact the appearance of the lighting. Low pressure sodium lights tend to produce light that is yellow or green in color, and is considered unattractive by most people. High pressure lights have a more natural, pleasing color that ranges from orange to pink. According to Energy Savers, the color produced by high pressure lights has a Color Rendition Index of 25, which is considered poor, while low pressure lights have a CRI of -44, which is considered extremely poor. Because of their low CRI rating, low pressure lights should only be used where the appearance of the lights is a very low priority.
- 3). Evaluate the life expectancy of each bulb. According to Energy Savers, high pressure sodium lights generally last from 16,000 to 24,000 hours, while low pressure lights only last from 12,000 to 18,000 hours. If the fixtures are in an area that's difficult to access, stick to high pressure lights, which will require maintenance less often.
- 4). Think about the size available for each fixture. High pressure lights contain smaller bulbs, which result in a more compact fixture, while low pressure lights require much larger bulbs and larger fixtures. If limited space is available, look for high pressure sodium lights.
- 5). Compare efficiency levels for each fixtures. According to the US Naval Observatory, low pressure sodium lights are the most efficient lights available in terms of lumens produced per watt of energy consumed. This may contribute to lower utility bills, especially in large applications such as street lights or stadiums.
- 6). Review the environmental impact of each of these types of lights. According to the New Jersey Department of Environmental Protection, high pressure lights may be subject to some restrictions because they contain mercury. This mercury content can pose a concern if the bulb is broken, or during disposal, when mercury is released into the atmosphere or local water bodies.
- 7). Consider light pollution. Because low pressure sodium lights have little color perception (or a low CRI), they contribute very little to light pollution. According to the US Naval Observatory, high pressure sodium lights have a higher CRI, and can thus contribute to light pollution levels. Light pollution is a concern for scientists and astronomers, as well as for many environmentalists.
SHARE
