Frequently asked questions on the utilization of extraction and filtration technology for removal and separation of viruses, bacteria, or disease germs
What size is the Covid-19 virus?
The size of the virus is between 80 nm and 160 nm (0.08 microns to 0.16 microns).
Extracted from dental procedures viruses are being transported by droplets and aerosols. Their size is even bigger than the virus – ranging from 200nm (0.2 microns) to 1,000nm (1.0 microns).
What are the mechanisms of filtration?
Size, weight and velocity of particles are crucial for filtration.
- Inertial impaction - Bigger particles are mostly captured by inertial impaction, or sieving (see below). They are being carried by the airstream and because of the inertia of their mass they hit filter media fibers and accumulate.
- Interception - Due to their smaller size and lesser weight, those particles are following the airstream more easily. They get stuck to the media fiber when following the flow stream around the fiber.
- Sieving - The space between two filter media fibers is narrow enough to sieve particles from the flow stream.
- Diffusion - Particles the size of e. g. viruses are small enough to NOT being impacted by the flow stream. They are following Brownish Motion and being captured by the mesh of different sized media fibers eventually.
What is Most Penetrating Particle Size (MPPS)?
Those are particles penetrating the filter entirely. Physics has it, that the size of the most penetrating particles ranges from 100nm (0.1 micron) to 300nm (0.3 microns). Particles within that range are too small for being intercepted (see What are the mechanisms of filtration?) but big enough not being filtered by diffusion.
What filter has the highest efficiency at Most Penetrating Particle Size (MPPS)?
HEPA filters (in Germany and Europe) are being tested according to the standard DIN EN 1822. The test aerosol the filters are being evaluated ranges from 100nm (0.1 micron) to 300nm (0.3 microns), exactly the most critical size spectrum -> Most Penetrating Particle Size (MPPS).
Particles smaller than 100nm (0.1 microns) and bigger than 300nm (0.3 microns) are being filtered at a higher efficiency than the MPPS.
There are several different standards for measuring the efficiency of filter:
HEPA (High Efficiency Particulate Absorption)
According to DIN EN 1822
Efficiency from H13 (99.95%) to H14 (99.995%) @ 0.1 to 0.3 microns
ULPA (Ultra Low Particulate Air)
According to DIN EN 1822
Efficiency from U15 (99.9995%) to U17 (99.999995%) @ 0.1 to 0.3 microns
MERV (Minimum Efficiency Reporting Value)
ASHRAE Standard 52.2-2007
Efficiency from MERV 1 (65%) to MERV 20 (99.999% @ 0.1 to 0.2 microns)
What is MERV and how does it relate to HEPA and ULPA?
H13 and H14 filters are considered Medical Grade Filters. The U15 certified (DIN EN 1822) ULT filter, does provide for an even higher efficiency.
What filter efficiency do the ULT filtration units have?
The main filter of all ULT filtration units is an U15 filter. This filter has an efficiency of 99.9995% at 0.1 to 0.3 microns. This class is equivalent to the highest MERV class – MERV 20.
How do I know that the filter is certified HEPA/ULPA?
Each and every ULT filter – first supply and replacement – is being tested individually according to DIN EN 1822. Each filter has a serial number and an individual test report. The test report is labeled to the side of the filter cassette.
What is the most efficient way of capturing extraoral aerosols?
There different capturing elements available on the market. Every process requires a unique way of capturing, due to the proposition of the contaminants.
The reach of each capturing element is given in times the diameter of the tube. For instance, an extraction arm with DN63 has a reach of 0.7 – that means the reach is 70% of the diameter of the arm -> 4.4.
The distance (reach) from the inlet of the capturing element to the patient’s mouth should not exceed 4 – 5 cm (2”).
What is the difference between a flexible extraction arm and a three joint extraction arm?
Flexible extraction arms are corrugated. Extracted aerosols settle inside the pleats of the arm and cannot be cleaned properly. Even disinfecting the outer surface of those arms is hard because of the corrugated surface.
How do I passivate the captured viruses and bacteria inside the ULT units?
The available heat unit RegBox150 provides for 65 degree Celsius (150 degree Fahrenheit) hot air for 60 minutes. The ULT filter unit (Jumbo, 160, 200) needs to be connected to the RegBox150 unit, with the motor running. After 60 minutes of flushing the filter with heated air, viruses and bacteria will be reduced, the filters will be dried and the moisture inside the extraction arm is removed. The RegBox150 will power down after 60 minutes automatically.
What do I need to do after every patient?
We recommend replacing the capturing element with a new one. Disinfect the used one before using it again.
Do the aerosols harm the filter?
No.The aerosol pre-filter is particularly designed to handle moisture from dental procedures.
How often do the filters need to be changed?
We recommend as follows:
Pre-filter once a week
U15 main filter every 6 – 8 weeks
What do I need to do, when replacing the filters?
Please read the manual carefully first. Passivate the filters by using the Heat-X unit as described, before changing.
How do I dispose the filters?
Please consult your local waste management provider.
Where do I get replacement filters?
Please contact your local Dental supply representative.
What sound level do the ULT evacuators have?
JUMBO DENT / ULT 160.DENT
54 dB(A) at 100% power
47 dB(A) at 50% power
58 dB(A) at 100% power
Some dental tools and equipment are even louder than 80 dB(A).
High cfm = high filtration efficiency?
Most manufacturer of air filtration devices advertise cfm as the main criteria for efficiency, making the end user believe the higher the better. Wrong – the cfm out there are usually the max. cfm capacity of the blower (fan) with no filters applied. With filters applied the pressure increases, reducing cfm tremendously. For instance, a blower with max. values of like 1,900 cfm @ 14” wc (3,450 Pa) provides for nominal 710 cfm @ 10”wc (2,000 Pa) with filters applied to the filtration unit – and it is getting even less than that with accessories like extraction arms or ducts attached.
Bottom line is that the entire system needs to be evaluated – from the capturing element, to the extraction arm, to the filters, to the blower. A well-balanced air filtration unit makes the difference.
On a side note: an extraction arm with a diameter of 2” and a length of 55” can physically only handle as much as approx. 60cfm. There is no sense in going big with the blower.
Does the ULT extraoral aerosol evacuator replace any other safety measures in place?
No. The ULT extraoral aerosol evacuator does NOT replace any other safe measures. It adds an additional safety measure to the already existing set-up.
In the case you have further questions not mentioned here, don't hesitate to contact us: