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Why a led panel light turns yellow after a period of application?

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Why a led panel light turns yellow


How to choose the right led panel light for your lighting application?


Led panel lights have been a very popular lighting product applied to the led commercial lighting application such as shopping mall, super market, office etc. There are several common specification of the led panel lights with dimension like 600X600mm, 1200X300mm, 600X300mm etc, most of these lights look similar with the outside shape, white color with frame structure, slim and modern design, easy to be installed to the false ceiling. As the panel light is with high energy efficiency and lumen output, usually used to replace the traditional fluorescent lamps.


If we check the components of the led panel lights, we could get the following related most important components:


1: Light guide plate-  to transmit and distribute the light evenly outwards and maximize the uniformity of light


2: Led chips- key point to decide whether it is a high efficacy or low efficacy led panel light


3: Led driver- if to use a high PF led driver or a low PF led driver


4: Aluminum frame- if it is with good heat-dissipation, anodized, strong structure or not.


Based on the points above, the point 1 about the light guide plate is a common point that would be neglected by normal users who want to purchase the led panel lights, there are several main light guide plates as follows for led panel lights of today:


Types of led panel light guide plates comparison


    Comparison Items

Material

Material

Material

    Led guide Plate

PMMA

polymethyl methacrylate

    PSA-polystyrene anti- 

    yellow, antioxidant

    PS-polystyrene

     transmittance(%)-average

    92%

    90%

    90%

    water absorption(%)

    2%

    0.02%

    0.02%

    expansion rate   (%)60°C   

    85% RH

    0.26

    0.10%

    0.09%

    Anti-UV

    best

    better

    bad

    yellowing (   years/rate)

    yellowing after   5 years

2% rate of yellowing   after 3 years

    3~5% yellowing after 1 year

    Price

    high

    Medium

    normal

    Advantages

Maximum resistance to yellowing

    high resistance  to yellowing

normal resistance   to yellow, cost efficient

    Disadvantages

high cost, high expansion rate to squeeze the led lights, make it produce blue or purple 

lowexpansion rate, high cost than polystyrene material


longtime application under high temperature and high humidity willincrease the rate of yellowing


 Total life   time for panel light

50,000hrs( normal temperature and humidity)-no yellowing

30,000hrs( normal temperature   

and humidity)-no yellowing

30,000hrs(not guarantee the yellowing)- the rate 3~5% yellowing



From the comparison, we could see that the PMMA has the longest life time with 50,000hrs, and the PS is not so good, although it could last for 30,000hrs time, but the rate of the yellowing is like 3~5%, which means you need to replace this percentage of the led panel lights during each year with 3 years, there is a good option if you choose the PSA  guide plate panel light, it could last for 30,000hrs without yellowing and this  is a balanced way considering  PMMA has a higher pricing. However, the PMMA also has a disadvantages that would turn the light color to be blue or purple due to its higher expansion rate.


Generally speaking, if you want a led panel light do not have any yellowing issues within 50,000hrs, PMMA is the choice, if you want a led panel do not have yellowing  issues with 30,000hrs, PSA is a better choice, if you want just a simple led panel light that could have about 30,000 hrs  but could accept the rate of the yellowing, the PS is the choice, as simply,  the price of PMMA is highest, PSA is the middle level, while PS is the cheap level.  Based on your project requirement and acceptance, you could have your options to make. 


yellow panel.jpg


In terms of the LED light panel driver, led driver has types of high power factor or low power factor,  the flicker of the led panel light  is generally caused by the driver ripples. A high power factor value led light usually comes with flicker that could not be perceived by our human eyes, but it could be visible if you check the light through a screen of the cell phone.  Low power factor panel light consumes a lot of energy and power with high cost for panel lights with higher wattage, as a result, most of the led panel lights are with high power factor driver.


For the aluminum frame of the LED panel lights shall use quality aluminum materials, well-shaped and designed with fast heat dissipation, anodized, anti-corrosion, strong structure.


Conclusion:


When you are considering  a suitable led panel light for your lighting application, you may need  to consider the following  points for your reference:


1:how many years of the led panel lights that  you need it to keep normal situation and do not turn yellow?


        - this will help you to choose the light guide plate, as the guide plate price is a main point of the panel light price.


2:Whether a high lumen output  led panel light is needed?


        - lumen efficacy of the led panel light usually comes with 70~110 lumen /watt,  higher lumen means higher price, choose the suitable lumen efficacy of the panel light is the best  way.


3:How many years of warranty that you need for your led panel lights?


        - this is an overall consideration, related with the panel guide plate materials, led driver life time whether is 30,000hrs or 50,000hrs, total components  come together for you to evaluate the product life time if worth 5 years warranty, for example, even you use a PMMA guide plate panel light, the led driver is 30,000hrs , this is not the right combination for a 5 years warranty panel light  even if  you may get  5 years warranty offered by some of the suppliers.

About our led panel light products:


About our led panel light products:


HYSPECTRUM offers a wide range of the led panel lights for different specification, our led panel light is from 90lm to 110 lm per wattage, energy efficient and modern design, our normal led panel light is with PSA material to provide a 3 years warranty,  for 5 years warranty led panel light is also available based on your  requirement, for product details, please visit our product  link:  https://www.hyspectrum.com/led-panel-light/

Shanghai HYL Technology Co.,Ltd.

Building No.3-5, No.118, Lane 3588, Qi Lian Shan Road, Shanghai , China

enquiry@hyspectrum.com

+86-21-400-038-5933

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