FAQ

FAQ General

[laɪlək]

Lilac is a pale violet colour.

Li.LAC uses ultraviolet light for disinfection.

Li.LAC was designed and is produced by LAC Labs.

Hence the name Li.LAC.

The irradiance chamber and the stainless-steel grill are optimized to accommodate three handheld microphones or three handheld transmitters.

It is also possible to disinfect other items.
Each Li.LAC is shipped with a spiral spring and a "Cable Tray" to support smaller objects like lapel or headset microphones or beltpacks.

Intense UV-C light (like the one used inside Li.LAC) has a wearing effect especially on plastics, foams and paint and powder coatings. We have done multipe long-time exposure tests with various microphones. The results show that the aging / wearing effect implied by UV-C disinfection inside Li.LAC  is negligible compared to the normal aging that happens to the microphones (due to mechanical impacts, dirt, humidity, temperature etc.).

The exact test results can be found here.

We do recommend that you do a test run with your specific microphone to ensure the compatibilty of the materials with exposure to UV-C light. The microphone membrane should not be exposed directly to UV irradiation. For handheld mics / transmitters we recommend to place them inside Li.LAC with the microphone grille (including foam) attached. For lavalier or headset mics we recommend to cover the membrane with a protection cap or foam windscreen. Also, we suggest to follow the recommendations of the microphone manufacturers.

Since the UV-C radiation does not penetrate the inside of the handheld or beltpack transmitter's housing, batteries can remain in the microphone without any problems.
The transmitter can also remain switched on.

But even the "naked" battery could theoretically be disinfected in Li.LAC. This could lead to accelerated aging of the plastic housing of the battery (see also here).

As most uv-c devices Li.LAC might leave a residual odor after the disinfection has completed.

This odor is not caused by ozone, as the uv-c lamps inside Li.LAC are so called "ozone-free" and do not produce any ozone.

The slightly sulfuric smell is a result of the uv-c light destroying and interacting with organic substances on the microphones.

We recommend to "air" the microphones for a few minutes after the disinfection to reduce the odor.

The UV-C sources inside Li.LAC are low-pressure mercury vapor lamps of the latest generation.
These lamps have a high efficiency at the dominant wavelength of 254nm.

Eyes or skin should not be exposed to direct or reflected ultraviolet energy emitted by these lamps. Exposure of skin to UV-C light can produce rapid sunburn and skin cancer. Exposure of the eyes can produce extremely painful inflammation of the cornea and temporary or permanent vision impairment, up to and including blindness in some cases.

The irradiation chamber of Li.LAC is light tight and no harmful UV radiation is emitted outside the chamber. The UV-C lamps can only be activated with the hatch closed.

A safety switch immediately deactivates the UV-C lamps, if the chamber gets opened while the disinfection process is running. The ultraviolet emission through the gap around the hatch is <0.5µW/cm².
The UV-C emissions outside of Li.LAC are below the limit values for classifying a photochemical hazard according to DIN62471:2009.

Operating conditions: room temperature (0°C to 40°C)

Power supply and mains voltage: 110-240V~ or 220-240V~ ±10%, 50-60Hz, 50W

UV-C wavelength: 254nm

UV-C irradiance @ microphone head: >800µW/cm²
UV-C irradiance @ microphone shaft: >350µW/cm²

UV-C lamps life time: 9000h (according to lamp manufacturer). We recommend to replace the UV-C lamps after 5000 disinfection cycles in order to ensure an optimum disinfection level.

Dimensions (WxHxD): 482mm x 132mm x 390mm (430mm incl. handles), 19" 3U rack format

Weight: 11kg

FAQ Disinfection

Ultraviolet germicidal irradiation (UVGI) is a disinfection method that uses short-wavelength ultraviolet (UV-C) light to kill or inactivate microorganisms by destroying nucleic acids and disrupting their DNA, leaving them unable to perform vital cellular functions. UVGI is used in a variety of applications, such as food, air, surface and water purification.

The electromagnetic spectrum

UV light is electromagnetic radiation with wavelengths shorter than visible light but longer than X-rays. UV is categorised into several wavelength ranges, with short-wavelength UV-C considered "germicidal UV". Wavelengths between about 200 nm and 300 nm are strongly absorbed by nucleic acids. The absorbed energy can result in defects including pyrimidine dimers. These dimers can prevent replication or can prevent the expression of necessary proteins, resulting in the death or inactivation of the organism.

References and more information on UVGI can be found here.

Li.LAC uses two low pressure mercury vapor lamps that emit UV light at a wavelength of 254nm (253.7nm to be exact).

The effectiveness of disinfection through UV-C depends on the duration of exposure, the intensity and wavelength of the UV radiation and the microorganism's ability to withstand UV during its exposure.

In air and surface disinfection applications the UV effectiveness is estimated by calculating the UV dose which will be delivered to the microbial population.

The UV dose is calculated as follows:

UV-dose H [mJ/cm2] = UV-irradiance E [μW/cm2] × exposure time [seconds]

The threshold dose H90% [mJ/cm²] for inactivation of different organisms (LD90, 90% inactivation) with UV radiation of 254nm can be found e.g. in DIN 5031-10:2018-03.

Examples according to DIN 5031-10:2018-03 are:

Microorganism

H for 90% inactivation [mJ/cm²]

Bacteria Escherichia coli

0.7 to 3

Bacteria Staphylococcus, Streptococcus

2 to 5

Influenca virus

3.5

For example for bacteria Staphylococcus the reduction at dose H is:

 Reduction by %
 Reduction by decades
 H [mJ/cm²]
 90
 1
 5
 99
 2
 10
 99.9
 3
 15
 99.99
 4
 20

The UV-C irradiance inside Li.LAC was tested and verified at the accredited test laboratory Opsytec Dr. Gröbel GmbH (DAkkS registration number: D-PL-20284-01-00). According to the test certificate the lowest irradiance inside Li.LAC is: Emin = 373µW/cm².

After a 5 minute exposure the minimum dose inside Li.LAC calculates to:
H5min = 373µW/cm² x 300s = 112mJ/cm²

According to the above mentioned literature values, bacteria and viruses are inactivated to >99.99% after 5 minutes of irradiation inside Li.LAC.

Microbiological tests were not performed. This evaluation is transferable to other microorganisms based on literature data (for example DIN 5031-10:2018-03).
OSRAM provides a list of LD-90 (90% inactivating) doses for various microorganisms. NB: the values in the table on page 4 are in [Ws/m²] = [J/m²], 1Ws/m² = 1J/m² = 0.1mJ/cm².

Recent studies (here or here) show that the irradiation dose for inactivating 90% of corona viruses is between 4mJ/cm² and 12mJ/cm². Following the example calculation above, the dose for inactivating 99.99% of corona virus calculates to:
H99.99% = 4x 12mJ/cm² = 48mJ/cm²
The lowest UV-C dose inside Li.LAC after 5 minutes is well above this required value.

Yes, there is.

We wanted to know exactly how well the UV-C irradiation inside Li.LAC would inactivate viruses on the complex surface of a real microphone, including the metal grille and the foam underneath.

The departments Biomedical Engineering and Medical Microbiology & Infection Prevention of the University Medical Center Groningen (UMCG) have conducted comprehensive scientific studies to evaluate the effectiveness of Li.LAC.

Viruses were sprayed onto microphones*, similar to singing into the mic. The results show a reduction of 99.3% of the viral load on strongly contaminated microphones (including the metal grille and foam) after 10 minutes irradiation inside Li.LAC.

Read more

* Industry standard vocal microphones were used for this study.

The longer the UV-C radiation lasts, the better the disinfection.

Roughly one can say that doubling the disinfection time allows a better reduction of germs by about a tenth.
The optical proof of effectiveness for Li.LAC (see FAQ above) shows that after 5 minutes 99.99% of most viruses and bacteria on the surface of the microphone have been destroyed. The virological studies by the University Medical Center Groningen (UMCG - see FAQ above) not only looked at the surface of the microphone, but also at the complex microphone grill and the foam underneath. In these experiments, viruses were sprayed onto the microphone similar to singing into the mic. These studies show a reduction of 99.3% after 10 minutes of irradiation inside Li.LAC.

What does that mean in practice?

The reduction of viruses and bacteria after 5 minutes is already very good. After 10 minutes, the level of disinfection is even better.

If you need the microphone right away because the next performer is already waiting at the stage entrance, then the short program makes sense. If there is enough time, one can use the long program.

The irradiation chamber and the steel grille are optimized for disinfecting up to three handheld microphones or handheld transmitters.

All boundaries of the chamber are coated with aluminium, UV-C-optimized, diffusing mirrors.
The distribution of UV-C energy is NOT homogeneous within the chamber!

The microphone shaft (the lower half of the microphone) is exposed to an irradiation of approx. 350 to 600µW/cm².
This energy is sufficient for reducing microorganisms on flat surfaces (like the mic shaft) without wearing out UV-C sensitive plastic parts like for example the acrylic display glass on a handheld transmitter.

The microphone head (with metal grille and foam) are exposed to a higher irradiation of approx. 800 to 6000µW/cm².
The higher energy and the highly diffusing mirrors of the chamber ensure a sufficient all-side exposure of the metal grille and the foam underneath.

It is important to understand that any kind of shadowing effect (for example by putting too many items into the chamber) will reduce the effectiveness of the disinfection.
This is similar to getting tan lines on your arm because of wearing a watch during the summer.

FAQ Support

Please have a look at the "troubleshooting“ table below.

OR:
Send an email to support@lilac.works

 

Problem
Possible cause
Solution
Display remains dark
No electrical power 
Check if Li.LAC is connected to mains voltage.
Check if mains fuse is blown.
Display shows "LAMP ERROR"
One or both UV-C lamps are broken or missing

Replace both UV-C lamps.

Precisely follow the instructions in the user manual.

OR

Send us your Li.LAC for maintenance.

UV-C lamps got damaged or cracked

Very intense mechanical impact or vibration

The UV-C lamps contain a small amount of mercury.

Follow these instructions for handling a broken lamp.

Display shows "Lamp replacement recommended"
The UV-C lamps have been used for >4000 disinfection cycles.

Replace both UV-C lamps to ensure the effectiveness of disinfection.

Precisely follow the instructions in the user manual.

OR

Send us your Li.LAC for maintenance.

Display shows "XYZ ERROR"
An internal error was diagnosed.

Please contact support. Li.LAC needs to be sent in for repair.

It is important to keep the mirrors inside the irradiation chamber clean and dust free.
Please follow the cleaning instructions in the user manual.

We recommend to replace the UV-C lamps inside Li.LAC after 5000 cycles in order to ensure an optimum disinfection level. The display will show a warning message after 4000 cleaning cycles.
Please follow the "how to replace the UV-C lamps" instructions in the user manual.

OR:
Send us your Li.LAC for maintenance.

Please read and precisely follow the "how to replace the UV-C lamps" instructions in the user manual.

OR:
Send us your Li.LAC for maintenance.

The UV-C sources inside Li.LAC are low-pressure mercury vapor lamps of the latest gerneration.

They do contain a small amount of mercury and special care needs to be taken if the glass tube gets damaged.

Please follow the instructions "how to replace the UV-C lamps" inside the user manual.

AND

Follow the instruction provided by OSRAM.

Please click here to download the user manual.

Please click here to download the newest firmware.

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