A typical high-power white LED used in lighting is shown below in Fig. 1. The die emits blue light and is coated with phosphor. The phosphor absorbs a portion of the blue light and re-emits the light as other colours to fill in other parts of the visible spectrum and thereby provide white light. The spectral characteristics of the blue and the phosphor can be varied to produce practically any colour temperature. Typically a silicone dome is overmolded on top of the die and package. The LED is a completely solid-state device and has no air, glass or fragile filaments. This makes the LED extremely resistant to shock and vibration. The phosphor coating on the glass of the bulb makes it a large source size and therefore difficult to control the light distribution precisely.
Source: 2011 PCIC Presentation
Traditional light sources such as mercury vapour, high pressure sodium (HPS) and low pressure sodium (LPS) have poor spectral content and colour rendering. This leads to visual fatigue and confusion when working with coloured wires, safety plaques, liquids, objects or smoke.
http://www.lightingassociates.org/i/u/2127806/f/tech_sheets/High_Pressure_Sodium_Lamps.pdf http://ioannis.virtualcomposer2000.com/spectroscope/mercurylamp.html - Clear Mercury vapor lamp HQA 80 Watt, from OSRAM, at different operating stages after startup. From left to right: @3 seconds, @7 seconds, @15 seconds, @35 seconds, @1 minute.
LED lighting vs HPS - all you need to know
Dialight LED LightingTechnology Comparison: High Pressure Sodium
Technology Comparison Dialight Typical makeup of bulb material LED High Pressure Sodium
Power Consumption / Dimmability Dialight Energy savings and CO2 emissions reduction Replace 400W conventional light source with 150W LED High Bay for immediate energy savings of 60%, even more when you use dimming and proximity sensors. On average 100 Dialight DuroSite LED High Bays can reduce CO2 emissions by 125 tons per annum (12/7 operation). Dimming Dimming options for LEDs include STEP dimming for specified light level percentages or variable dimming for custom light output levels determined by the installer/customer. A special ballast is required to dim mercury vapor lamps. Light Source Watts Dimmability Dimming LimitHigh Pressure Sodium 100 – 500 Requires special 50% ballast LED 43 – 170 Yes 10%
Lumen Per Watt Efficiency Dialight Light Source Lumens/watt High Pressure Sodium 80-140 LED 114-160
Lifetime / Lumen Maintenance Dialight Light Source Lifetime in Hours (x1000) High Pressure Sodium 10-24 LED 100+
Color Quality Dialight LED High Pressure Sodium Light Source CRI Mercury Vapor 20-30 LED 70-90
Temperature Ratings Dialight Temperature Ratings Heat producing equipment is marked with a Temperature Code, to indicate the maximum surface temperature. HPS LED Ratings given at 40° C ambient temperature Light Source T Rating Mercury Vapor T2A – T3A LED T4A – T6
Mercury Content Dialight GE 400W Philips 1000W LED Mercury Content: 30 mg Mercury Content: 44 mg Mercury Content: 0 mg Disposal The Resource Conservation and Recovery Act (RCRA) and the Universal Waste Rule (UWR) regulate the disposal of lamps containing mercury. LEDs themselves contain no mercury or harmful materials, which require special handling or unique recycling. Light Source Mercury Content HPS ~ 6 mg/100W LED 0
Instant On/Off Dialight 400W HPS Lamp Startup Color Shift Warm up Time Restrike Time Light Source (minutes) (minutes) High Pressure Sodium 2 – 15 4–5 LED Instant Instant0
Operating Temperatures Dialight Light Source Operating Temperature (°C) HPS -30° to 65° LED -55° to 70°1