Question 1

What is UV light?

Accepted Answer

Ultraviolet light (UV) is supplied by the Sun in 3 bands of light/ energy

UV A band – Phototherapy, Cosmetic, Wound healing
UV B band – Cosmetic (Sun tanning), Skin disorders
UV C band – this frequency provides the required energy to inactivate the DNA structure in Air, Surfaces, and Water

Question 2

How UV-C works?

Accepted Answer

Germicidal ultraviolet (UVC) light kills cells by damaging their DNA. The light initiates a reaction between two molecules of thymine, one of the bases that make up DNA. UV light at this wavelength (shortwave UV or UVC) causes adjacent thymine molecules on DNA to dimerize. The resulting thymine dimer is very stable. If enough of these defects accumulate on a microorganism's DNA its replication is inhibited, thereby rendering it harmless.

Ultraviolet photons harm the DNA molecules of living organisms in different ways.
In one common damage event, adjacent bases bond with each other, instead of across the "ladder".  This makes a bulge, and the distorted DNA molecule does not function properly.
The longer the exposure to UVC light, the more thymine dimers are formed in the DNA. If cellular processes are disrupted because of DNA damage, the cell cannot carry out its normal functions. If the damage is extensive and widespread, the cell will die.

The LIGHT SPECTRUM ranges from the infrared at wavelengths longer than visible light to the ultraviolet at wavelengths shorter than visible light. Ultraviolet (UV) radiation is electromagnetic radiation of a wavelength shorter than that of the visible region.

Question 3

UV-C dosages VS microbes?

Accepted Answer

Sani UV-C assists clients with various applications depending on the sterilization required.

Although UV-C lights provide visible light, the light that is actually doing the work is invisible to the naked eye. This invisible light in its correct thermology is what we call radiation or irradiation.

Make sure to never work with UV-C without guidance from an expert or without the correct safety wear.

If you could see the invisible UV-C irradiation, this is what it would look like.

Germicidal Effectiveness of UV light frequency

Microbes are measured in their own value, as Joules.

To ensure the effective deactivation of microbes like viruses, bacteria, or fungi the most acceptable wavelength would be  UV-C 253,7 nm.

Irradiation sterilization effectiveness against bacteria, fungi, and viruses  over time

Germicidal irradiance emitted from a lamp is measured in microwatts per cm2 to deactivate or sterilize over a specific time.

The inverse square law of light shows reduced effectiveness over distance

Question 4

UV-C measuring devices?

Accepted Answer

This energy's effectiveness is measured using a UV-C meter and safety PPE.

The meters are great for guidance and calibrated devices are used by Sani UV-C when applying or designing effective fixtures.

Golidilux calibrated UV-C single most accurate variable

Question 5

UV-C Technology

Accepted Answer

There are many types of lamps that artificially produce UV. There are UV lamps for tanning, counterfeit money detection, blacklight stage lamps and lamps for mineral displays, lamps that produce Ozone, and germicidal UV lamps.

We are looking at the germicidal UV lamps, which emit shortwave UV light in the ultraviolet section of the specter also known as UVC or germicidal UV.

Here we will discuss the artificial UV production by the different UV lamps and the specs of the different types of UV lamps. Many times, people refer to the UV lamps as UV bulbs as in regular light bulb. Even though bulb is not the correct term, replacement bulb, UV bulb or bulbs are widely accepted in the industry as a reference to the UV lamps.

Question 6

UV-C using LED

Accepted Answer

The use of LED are relatively new to the market. Although effective the use of Light emitting diodes are expensive for long term use with shorter lifespans due to reliability.

Does Sani offer LED?
Our fixtures are designed for function and effectiveness with the aim to obtain maximum energy at the best operating cost. LED technology isn’t where we expect to see if as yet.

Can UV-C LED be a replacement for the UV-C Lamps?
For specific applications LED would if it is cheaper to maintain over time than that of lamps.

Are LED`s more powerful than Lamps?
LED lights use less power, also emit 2 wave angles. Where Lamps do use more power but provide 3 wave angles providing better irradiance over distances and corners.

Question 7

UV-C Lamps

Accepted Answer

Lamps have been used for years and although easier to replace do have to be replaced around 9000 hours ( 1 year). The use of UV-C 253,7 nm is proven yet must be applied to ensure safety and effectiveness. UV-C 253,7 nm is extremely effective but has risks when exposed to skin or eyes.

Although safer UV-C 222 nm technology has been developed we do find variances in effectiveness and use against specific families of bacteria.

Sani UV-C makes use of globally available lamps to ensure lamp availability for fixtures is made easy.

Does Sani offer 222nm? 
As yet the use of 222 nm lamps or LED is extremely expensive and not easy to maintain.

Can UV-C 2222 nm be a replacement for UV-C 253,7 nm?
With various families of bacteria and fungi when sterilizing or irradiance is used, we can find using variations and combinations of light the effective application. 
UV-C 222 nm is a weaker form of UV-C 253,7 nm. The use of UV-C 222 nm is suitable for public areas where if used in medical environments would cause risk. UV-C 253,7 nm is seen to be effective against stubborn larger gram-negative bacteria.

Types of UV Lamps

High Output Germicidal UV Lamps
The most recent addition to the UV lamp line of products is the type of High Output germicidal UV lamps. The HO lamps are the consequent result of constantly applied know-how and the latest lamp manufacturing processes. High UV output over a great temperature spectrum, long life, and good behavioral patterns are the pointers for High Output UV lamps. Only high-quality raw materials are used in lamp production. Fine-tuning with the automatic electronic ballasts guarantees the lowest tolerance and maximum UV stability.

With a life duration of 12,000 hours and almost linear performance degradation, high-output UV lamps are setting the standards for the development of high-performance UV technology.

The most important factor in using germicidal UV lamp technology is the knowledge about their behavior under real working conditions (e.g. the effect of air stream cooling). It is definitely not just the lamp's performance under laboratory conditions that count. Only by gaining this knowledge can high-quality disinfecting technology be achieved.

Taking the example of air stream cooling the High Output lamps do show their real advantage. While classic UV lamps heavily depreciate under real working conditions inside an air duct, this is not the case with High Output UV lamps.

Cold Cathode Germicidal UV Lamps

The Cold Cathode Germicidal UV Lamps are instant-start lamps with a cylindrical cold cathode type of electrode. These lamps are available in different sizes and may be operated either from single lamp transformers or in series through the medium of high-voltage transformers.

UV Lamp Aging 
The decrease in UV lamp output over the typical lifespan of 8,000 - 12,000 hours can vary between 15-40%. The manufacturer should be consulted for information on the end-of-life output of UV lamps. The decrease in UV output should be accounted for in the design phase such that the lamp output does not decrease to a point where the air treatment system becomes ineffective. The most conservative approach is to size the system based on the end-of-life of the lamp UV output. Selecting lamps based on end-of-life UV output will avoid the lamps aging problem.

The lamps should be kept clean and free of dust at all times. If dust accumulates on the lamp it will absorb the UV and convert it to heat, therefore lowering the effectiveness of the UV lamp. Appropriate filtration of the air prior to the UV lamps is recommended

Question 8

Why is UV-B harmful while UV-C (germicidal UV) is not?

Accepted Answer

The difference has to do with the ability of UV rays to penetrate body surfaces. UVC has an extremely low penetrating ability. It is nearly completely absorbed by the outer, dead layer of the skin (stratum corneum) where it does little harm. It does reach the most superficial layer of the eye where overexposure can cause irritation, but it does not penetrate to the top of the lens of the eye and can not cause cataracts. UVC is completely stopped by the ordinary eye glasses and by ordinary clothing.

Question 9

How much UV exposure is considered safe?

Accepted Answer

The National Institute for Occupational Safety and Health (NIOSH) has established safe exposure levels for each type of UV. These safe exposure limits are set below the levels found to cause eye irritation, the eye being the body part most sensitive to UV. For germicidal UV (253.7nm) the exposure limit is less than 0.2µW/cm² over 8 hours.

Question 10

How can people be certain they are not overexposed to UV?

Accepted Answer

When upper room UV is first installed it must be checked with a sensitive UV meter to make sure reflected UV is less than 0.2µW/cm² at eye level. UV air cleaners must be installed well above eye level - usually 7 feet above the floor. UV tubes (lamps) within the air cleaners should not be directly visible from within 30 feet. Safety is assured if UV measurements at eye level meet NIOSH standards.

Question 11

What are the symptoms and signs of UV overexposure?

Accepted Answer

UV overexposure causes an eye inflammatory condition known as photokeratitis. For 6 to 12 hours after an accidental overexposure the individual may feel nothing unusual, followed by the abrupt sensation of foreign body or "sand" in the eyes, redness of the skin around the eyes, some light sensitivity, tearing, and eye pain. The acute symptoms last 6 to 24 hours and resolve completely without long-term effects. Overexposure of the skin resembles sunburn but does not result in tanning.

Question 12

What precautions are needed with overhead germicidal UV?

Accepted Answer

Fixtures must be turned OFF when cleaning, inspecting or changing the lamps. Persons hypersensitive to sunlight may need to wear protective glasses, and clothing or use sunscreen on exposed skin.
No special protection is needed for most people

Question 13

Indoor Air Pollution. UV & Air Pollutants

Accepted Answer

Most people take the quality of indoor air for granted and assume the air is clean and safe to breathe. According to the American Medical Association 50% of all illness is caused or aggravated by polluted indoor air.

The air in today's buildings can contain different microbial contaminants such as bacteria, viruses, mold, fungi, and spores. Bioaerosols are airborne microbes, their fragments, toxins, and waste products.

Numerous studies have found high concentrations of such contaminants in the air handling equipment and in the air inside the places where people live and work.

These indoor air pollutants can make the air quality less than desirable, may even cause unhealthy effects ranging from allergies to tuberculosis, and are actually the cause of death to an estimated 8.5 million people annually.

Some studies state that properly designed and installed UV air cleaners will eradicate or greatly reduce microbial contaminants from the indoor air. This is why the indoor air quality in public buildings has been addressed by specific requirements of UV installation inside the HVAC systems.

When the problem of residential indoor air quality became apparent, ultraviolet technology became the proven answer to effectively controlling airborne microbial pollutants. The artificially generated UV can reduce or virtually eliminate all DNA-based air pollutants that regular filtering systems do not catch.

UV-C Basics

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