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How does the STL Professional Germicidal Air Processor (PGAP) compare to air purifiers using HEPA filters.

  • HEPA filters usually consist of many layers with smaller and smaller pores to trap particulates and bacteria. As the pores get plugged up by the filtered dust or germ, the ability of the filter to pass through clean air quickly reduces.
    So while a HEPA filter may work well during the first few days of operation, its efficiency quickly reduces after a week or two.

  • Cost of replacement HEPA filters can be very expensive.

  • HEPA filters trap the bacteria and some viruses but do not kill them. Depending on the filter construction, the filter may be providing a a niche for some germs to grow.
    When you want to replace that HEPA filter, someone has to remove the old filter very very carefully.

The PGAP actually kills the bacteria and viruses, and there is no filter to replace.

How do we know the PGAP can kill bacteria and viruses

PGAP uses high intensity UVC that is well documented to have the ability to kill germs. In fact many hospitals use UVC to sterilize their rooms and working tools. 
STL PGAP uses highest quality European made UVC lamps and then conservatively design the unit to kill off over 99.9% of bacteria and viruses in the first pass.

What is the operating life of the UVC lamps

The high quality UVC lamps we use in our PGAP units have a rated life of 9,000 hours. That is over 1 year if running at 24/7 full time. If operated only for 8 hours a day, it can last over 3 years.

Is the UVC lamp dead after 9,000 hours?

No. The UVC output decreases over usage-time. After 9,000 hours of usage, the UVC energy output is reduced by about 20%. That means some 80% of the UVC power still remains.
For mission critical applications, we recommend that the lamp be replaced after about 9,000 hours of operation.

Is maintenance service available?

We recommend having the unit inspected, checked and internal cleaned once every 6 months.
Contact STL by email at or WhatsApp 91438685 for up to date details on this service.

How do I maximize air processing efficiency?

  • Place the unit where airflow is not blocked

  • Place the unit near where there is most number of people

  • Place the unit near the air inlet of your air conditioning system

  • You can also consider raising the unit by placing it on a short table. Please make sure children and babies do not look up into the air inlet or down the air outlet within 6 inches of the unit to avoid injury.

How does Professional Germicidal Air Processor (PGAP) compare with Plasma air purifiers?

Plasma means ionized particles in the air. This gives the particles a tiny electric charge, typically a negative charge. When the dust particulates, bacteria, or viruses in the air are so charged, they will be attracted to the floor or walls or onto the clothing as someone walks by. The result is significant reduction in the amount of floating dust, bacteria and viruses in the air near the plasma generator.

However there are two major issues with plasma air purifiers:

  1. Plasma only gives the dust/bacteria/viruses an electric charge so that they tend to attach to a nearby surface. Plasma air purifier does not kill the bacteria or viruses. 

  2. The dust/bacteria/viruses that accumulate on the floor or walls near the plasma air cleaner are only weakly attached. If disturbed (e.g. someone walking near it), the particles will detach from the surfaces and bloom back into the air.

In a PGAP unit, over 99.9% of the bacteria and viruses are killed instantly.

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