TB Infection Control

To use Paul Jensen's words: *It all depends *and in all cases it will be
the specific design requirements and the unit manufacturers specification.
*
*Ceiling mounted units function well in square or oblong rooms with
moderate width/ length dimensions. These units provide a 360°
irradiation radius and if the rooms are to small there will be a lot of
reflection from the walls and it will affect the rooms occupants. When
using ceiling mount units care should be taken that only units with a
horizontal irradiation beam are used to prevent reflection from the
ceiling. Ceiling mount units are heavy, normally more than twice the
weight of wall mount or corner mount units. The load bearing capacity of
the ceiling/ roof structure must be investigated before a decision is
made. The correct unit position may interfere with other existing
services in existing buildings.

Wall mounting units are generally easier to install because they are not
as heavy as ceiling mounted units. Care must be taken when they are
fixed against partition/prefabricated walls. They work well when
installed against the walls of square and oblong shaped rooms. Care
must be taken to ensure that the units suit the application ...

To use Paul Jensen's words: *It all depends *and in all cases it will be
the specific design requirements and the unit manufacturers specification.
*
*Ceiling mounted units function well in square or oblong rooms with
moderate width/ length dimensions. These units provide a 360°
irradiation radius and if the rooms are to small there will be a lot of
reflection from the walls and it will affect the rooms occupants. When
using ceiling mount units care should be taken that only units with a
horizontal irradiation beam are used to prevent reflection from the
ceiling. Ceiling mount units are heavy, normally more than twice the
weight of wall mount or corner mount units. The load bearing capacity of
the ceiling/ roof structure must be investigated before a decision is
made. The correct unit position may interfere with other existing
services in existing buildings.

Wall mounting units are generally easier to install because they are not
as heavy as ceiling mounted units. Care must be taken when they are
fixed against partition/prefabricated walls. They work well when
installed against the walls of square and oblong shaped rooms. Care
must be taken to ensure that the units suit the application and prevent
reflection from walls. These units are also suitable for rooms with
ceilings higher than 2.8m. They will irradiate a volume above the safe
eye level, 6ft or 1.8m above floor level. It may be difficult to support
360° units on long pendants where there are high ceilings or no
ceilings. With correct designed reflectors to beam the irradiation
sideways, wall mounted units can be effectively used in in passage ways.

Corner mount units are mostly meant for small rooms and the type of unit
intended to use must suit the room size and required ceiling height.

Dries Meyer.
()

I agree that wall mounted units are the easiest and best way to go. The problem with all the UVC systems is that you need too many of them to give an effective result per hospital and in terms of upfront purchase, installation and maintenance many (most) government hospitals is South Africa cannot afford the systems.

Dear Hennie,

This is a response to both your recent postings (and I see that there is now a 3rd - you are hard to keep up with). Your statement contains many valuable points, and also many generalizations that do not apply across the board, and some that are untrue. This is not a discussion about ceiling mounted versus wall mounted, which are similar approaches, but about upper room UVGI versus other means of air disinfection.

As you know, there is an official (if unwritten) moratorium on using UVGI in South Africa pending better installation guidelines and better, less expensive, more effective and safer equipment. I think that is a wise move as there is much to do before UVGI can be wisely used in South Africa and other settings. I have never suggested that upper room UVGI is the best approach to air disinfection in any given setting, as this is a case by case decision. What I have said is that from a cost effectiveness perspective, under ideal conditions, natural ventilation is most cost effective, upper room UV next, air filtration next, and finally HVAC systems. There are also problems with each of these approaches. Natural ventilation requires both ...

Dear Hennie,

This is a response to both your recent postings (and I see that there is now a 3rd - you are hard to keep up with). Your statement contains many valuable points, and also many generalizations that do not apply across the board, and some that are untrue. This is not a discussion about ceiling mounted versus wall mounted, which are similar approaches, but about upper room UVGI versus other means of air disinfection.

As you know, there is an official (if unwritten) moratorium on using UVGI in South Africa pending better installation guidelines and better, less expensive, more effective and safer equipment. I think that is a wise move as there is much to do before UVGI can be wisely used in South Africa and other settings. I have never suggested that upper room UVGI is the best approach to air disinfection in any given setting, as this is a case by case decision. What I have said is that from a cost effectiveness perspective, under ideal conditions, natural ventilation is most cost effective, upper room UV next, air filtration next, and finally HVAC systems. There are also problems with each of these approaches. Natural ventilation requires both good building design and good climatic conditions, and does not work if windows are closed at night due to cold or security. Room air filtration (or internal UV) machines and HVAC are the most expensive and technically problematic in poor settings.

The number of UVGI units depends on the settings, but could be many units for large wards and the price does add up. However, if when optimally done it is the most reliable and cost effective, what choice is there? UV in a box is the equivalent of room air filtration machines and depends on airflow through the box and is NOT recommended because very few equivalent air changes per hour. Upper room UVGI can be used safely if properly planned and with good equipment. We are working to get safe designs available to the international community.

Ed

While we're on the subject of costs of UVGI, from my understanding of these systems, the bulk of the costs go into the lamp. This was the same problem with fluorescence microscopes. I know for a fact that many companies have been investing in designing UV lamps using LEDs. Power is a big problem, but stacking multiple LEDs has been one way around (at present).

Would anyone have an update on where the technology is at present viz a viz LED based UV lamps? That'll give us an indication whether Upper Room UVGI has a near term future in terms of sustainable implementation.

Thanks
Sriram

uvc led's with sufficient output for germicidical usage are probably 18 -24 months away, and will be expensive. ....probably 3 years until they become sufficiently ubiquitous and affordable.. On affordability, who is tasked to determine what is affordable dollar rate per m3 of uvc irradiation in 3rd world countries? The criteria re safety et al are established and known, but the affordability determines the rest. Any ideas?

Ed is correct. The discussion is about upper volume UVGI versus other air disinfection methods.

I will repeat the basic principle for upper volume UVGI because it seems to me that this principle is unknown to some participants.

The principle is: Slow moving infected air circulating through a large volume of upper air irradiated with a low dose of UV-C.

This was clearly confirmed in the Riley experiment with a 36W nominal rated UV-C lamp and a ceiling fan. The results of this experiment can be easily found on the Internet.

UVGI and air circulation must be combined in the design to provide an efficient installation.

To date the most cost effective method for air disinfection, in most cases, was found to be upper volume UVGI, but only if the installation was correctly designed.

The RSA is privileged to have the Goniometer test lab run by Prof Wilhelm Leuschner, where the parabolic curves of UVGI units can de determined. I must however still find the manufacturer/ supplier who can use the excellent information provided to do a proper design. Most "designs" are done by incompetent salesmen who over design with cheap low efficacy units and do not allow for the ...

Ed is correct. The discussion is about upper volume UVGI versus other air disinfection methods.

I will repeat the basic principle for upper volume UVGI because it seems to me that this principle is unknown to some participants.

The principle is: Slow moving infected air circulating through a large volume of upper air irradiated with a low dose of UV-C.

This was clearly confirmed in the Riley experiment with a 36W nominal rated UV-C lamp and a ceiling fan. The results of this experiment can be easily found on the Internet.

UVGI and air circulation must be combined in the design to provide an efficient installation.

To date the most cost effective method for air disinfection, in most cases, was found to be upper volume UVGI, but only if the installation was correctly designed.

The RSA is privileged to have the Goniometer test lab run by Prof Wilhelm Leuschner, where the parabolic curves of UVGI units can de determined. I must however still find the manufacturer/ supplier who can use the excellent information provided to do a proper design. Most "designs" are done by incompetent salesmen who over design with cheap low efficacy units and do not allow for the important air circulation.

We also have a large number of upper volume UVGI units in the market. The problem is that most of them are not worth the paper on which they are advertised. I am to a certain extend "privileged" to have had the opportunity to test most of the units on the market for Clients who wanted an "as installed test" done before they awarded a tender. The results were shocking. I found ceiling units with two small fans with the air inlet sides opposing each other and apart from this the outlet airflow was restricted by ± 50% because the outlet air is directed to the inside of a disk. Units with internal reflectors to limit the output of the lamps which lowered the efficacy of the units with more than 40%. Units designed for 5 x horizontal reflectors, sold with 4 x reflectors to lower production cost, sold at the same price of the 5 x louvred units. This is but a few examples.

Then there are the manufacturers/ suppliers who do not know the difference between upper volume UVGI units and small wall mount units. When tenders call for upper volume units, they quote with cheap, small, highly inefficient wall mount units. I have tested the air flow of several of these units. One could only laugh at the results.

The biggest problem is that manufacturers of these units do not know the difference between the nominal air flow rating of a fan and the actual airflow measured at the outlet grill of the unit. They do not have air flow meters and one of them told me he had a meter, but lend it to somebody else. He could not use a meter when I handed him mine. The units are advertised with for instance 60, 70 or 80m³/h air flow fans. I tested most of these and found actual air flows of 3.84 to 17.4m³/h. The main problem is that these units are not capable of providing the 10 t0 12 ACH as required for TB facilities. One of these small units is advertised to provide air disinfection for an area of 200m². Air disinfection can only be applied to a volume of air. I made a calculation and found that with a ceiling height of 2.7 meters, 31 of these units will be required, not one as advertised.

Some of the above units also boast that they include titanium dioxide as a silver bullet to all TB infected air disinfection problems. To my knowledge the CDC, Harvard, Pennsylvania State University or any other reputable entity accepted titanium dioxide for TB infected air.

As for Hennie Mostert's comment the the University of Pretoria is busy with the development of an upper volume UVGI unit. I do not know of this insinuation. The only person that can provide an answer is Prof Wilhelm Leuschner.

The drawing up of a design standard for upper volume UVGI units and installation design standards remains a serous problem. This does not only apply to the RSA. I have been involved in the UVGI discipline since 1998 and was told from then up to this date that somebody or some Authority will be appointed or is appointed to do the work. Unfortunately there is no visible evidence to date. This is also why the "smoothest talking rep" for a UVGI manufacturing company gets the tender.

I was told by an ex donor for UVGI units that he will never do it again because manufacturers "smell money" and then they go "biz irk" with the high prices.

Dries Meyer.

At present it seems that the availability of LED UVGI is still, only to a certain extend available for micro type installations due to the low UV-C emission of the LED's.

I look at the lamp life of UV-C lamps supplied by manufacturers as a sales "insurance". They do not know under what conditions the lamps will be used. The lamp life depends on the environment in which it is used. If the lamp is used in conditions where the lamp temperature is above or below the optimal temperature provided by the manufacturer, the lamp life will be affected.

Grigory Volchenkof made extensive and very practical tests on UV-C lamp life. He submitted this to GHDonline before, but he maybe kind enough to do it again.

Dries Meyer.

The estimated cost of one additional equivalent ACH provided by upper room UVGI fixture (one Phillips TUV-30 lamp)in the patient room in our study was around 14,5 USD per year (capital, installation, maintenance, supplies, electricity costs included).

Dr. Grigory V. Volchenkov

Head Doctor
Vladimir Oblast TB Dispansery

Sudogodskoe shosse, 63
Vladimir 600023 RUSSIA

phone/fax work: +7(4922)323265
mobile +7 9206253227; +7 9190189226

PPlease don't print this e-mail unless you really need to. Thank you!

Dear all,
I agree with Ed that the responses to this discussions have gone a bit beyond the scope of this forum,but I also admit I have learned a lot reading your valuable inputs. It will certainly help me when advising those who might be thinking of using UVGI as an ultimate tool for air disinfection. Many thanks.Luciana
Sent from my BlackBerry smartphone from Virgin Media

As I already posted in "Room air cleaners" my story once again. I really think we sometimes loosing track of what is needed and asked in the first place. There might be so many future "better" solutions but in most LMI countries we have not the perfect situations we refer too. I don't directly see the problem with the initial purchase cost of these units. It is rather easy to find a sponsor for the units only. The first and main problem comes when the units get installed, regardless if this is UVGI, simple extraction or room air cleaners. A lot of these installations are done in an unprofessional way, either by instruction of doctors that attended a technical course and call them self engineers now, by a local electricians with no specific knowledge of UVGI or ventilation or by the in-house janitor because nobody else does the installation. Most of the time there is no money/funding available for local engineers or foreign specialist to help with the proper installation or inspection during installation, as this was not part of the initial application for funding of these units. Wrong installation brings in high risk.
The second problem comes ...

As I already posted in "Room air cleaners" my story once again. I really think we sometimes loosing track of what is needed and asked in the first place. There might be so many future "better" solutions but in most LMI countries we have not the perfect situations we refer too. I don't directly see the problem with the initial purchase cost of these units. It is rather easy to find a sponsor for the units only. The first and main problem comes when the units get installed, regardless if this is UVGI, simple extraction or room air cleaners. A lot of these installations are done in an unprofessional way, either by instruction of doctors that attended a technical course and call them self engineers now, by a local electricians with no specific knowledge of UVGI or ventilation or by the in-house janitor because nobody else does the installation. Most of the time there is no money/funding available for local engineers or foreign specialist to help with the proper installation or inspection during installation, as this was not part of the initial application for funding of these units. Wrong installation brings in high risk.
The second problem comes in during the operation period. Believe it or not, not but there are hospitals that use their UVGI and ventilation 40 minutes a day as there is not enough funding to pay the electricity bill. As with the fact that there is no money to appoint qualified engineers for installation, there is seldom money for maintenance. The staff sees it as an addition task to clean up equipment, where they already trying to coop with the over loaded facilities. Cleaning staff seldom knows how to clean equipment. Cleaning a mobile HEPA unit with a cloth on the outside is not regarded cleaning the unit. Block filters and intake grills are more common than the exception.
If people not get properly educated, the right people are not appointed for installation and funding is only available for the purchase of goods, we can discuss in lenght the benefits and disadvantages and the possible new inventions of the different pieces of equipment, but we will not find a proper solution for the LMI countries. Yes we need standards and parameters but with that come proper education and the responsibility by the people who order and install this equipment.

Hans Mulder
Environmental Architectural Consultant c.c.

Po Box 90777
Windhoek, Namibia
+ 264 61 255446 (office)
+ 264 81 252 4080 (cell)