Wednesday, April 25, 2012

Reviewing ASHRAE DL Speakers

I made a couple of visits to speak at Canadian ASHRAE chapters last week in Montreal and Ottawa. Everyone was extremely friendly; we had a huge attendance at both chapters - over 125 in Montreal. My talk went well, even though I am not conversant in French. It seems English is pretty well understood there.

I heard repeatedly that I was one of the best speakers they had ever had. I often get that comment, and at the same time, I hear how dull and uninteresting most ASHRAE talks are, especially with the ASHRAE Distinguished Lecture (DL) speakers. There are lots of ASHRAE DL speakers. A good number of them, in an effort to establish international credibility and recognition (ASHRAE Officially dropped the “American” name when it became simply “ASHRAE”), are not fluent in English. More, it seems, are just plain dull.

Based on all the feedback I get, the reason folks like my talks is that they are interesting, sometimes humorous, informative, and always clearly making a point. Sadly, is seems many are informative, but miss the other attributes. I understand that we are mostly engineers. Engineers have a reputation for being linear thinkers and somewhat boring - but we don’t have to be. Dull speakers result in folks not ‘bothering’ to attend meetings, which is sad, because it reduces the potential for ASHRAE Engineers to gain new learning experiences. We have to make the talks interesting if we want our message to get out. This is assuming, of course, that we have a message. Sometimes I suspect, there is no message, just a data dump, which usually results in no message being retained.

So what’s my message (you suddenly ask)? Fill out the feedback forms when an ASHRAE DL speaks. Don’t be shy about your comments. If the speaker was boring, please let ASHRAE know. If he was terrific, let ASHRAE know that too. Maybe we can weed out the bad talks so more will attend the ASHRAE sessions.

Authored by: Dan Int-Hout, Chief Engineer Krueger

Thursday, April 12, 2012

Hospital Operating Air Systems and ASHRAE 170

There have been a number of recent calls regarding the application of the Krueger Sterilflo air curtain system and the requirements of ASHRAE 170, the Hospital Ventilation Standard. When we noted to the committee developing 170, the chair insisted that 170 did not prohibit an air curtain system, but does not endorse them either. He mentioned that there was (at that time) no ASHRAE peer reviewed paper on air curtain systems. Gerry Cook and I immediately prepared one, and it was presented at an ASHRAE seminar. The paper has been turned into a Krueger White paper which can be found at Nonetheless, the standard was published without mention of the air curtain type of hospital operating room air delivery system.

In short, the ASHRAE Standard wants to see a series of “non aspirating” laminar panels over the patient with the rest of the required airflow delivered vertically, but not necessarily from a non-aspirating diffuser. There are two realities that one must resolve in attempting to meet this standard’s requirement. The first is that no laminar panel system is truly “non aspirating”. The committee actually witnessed this fact in a manufacturer’s lab during one of the ASHRAE meetings. Laminar panels induce some air at the perimeter of their area. The second is that this induction adds to the mass of air traveling down towards the patient’s table, increasing the table velocity. There is also the “coke bottle” effect in which the colder air tends to contract the downward air pattern, also increasing the velocity at the table. Finally, the greater the number of adjacent panels, the greater the “mass effect” which also increases the local air speed at the table top. There is a great likelihood that an all panel system will exceed the velocities specified at the operating table with the required face velocities at the panels, due to all the effects listed.

An air curtain system keeps the size of the panels as small as possible (avoiding the mass effect), and the air curtain prevents the induced air from coming outside of the sterile area surrounding the patient. Tests have been conducted measuring viable particles during actual operations (a while back, as it is unlikely one could do so today with the potential liabilities that exist these days). These tests confirmed that the air curtain system is much less likely to create a non-sterile condition than a standard laminar panel system.

Meeting ASHRAE 170 is simply a matter of managing the areas of panels and air curtains to comply with ASHRAE 170.
Authored by: Dan Int-Hout, Chief Engineer Krueger

Tuesday, April 3, 2012

The New Facility is Operational!

After several months of construction, and much longer planning, the new Krueger Lab, Training, and Demonstration Center is operational. We held an Open House a couple weeks ago and the first of our revamped Krueger Institute of Technology training sessions last week. During training, we demonstrated diffuser performance with smoke at several different discharge temperatures, including tests against our unique double sided Cold Wall.

The Reverb Room is operational, nearly twice the size of the one in Tucson AZ, and with far greater airflow and sound isolation capabilities than ever before. The Throw Bay is twice as long as our previous one. In Tucson, with the highly accurate omni-directional anemometers and computer acquisition system, we discovered that one could see the effect of an opposite wall when within 20 feet of it, severely limiting the ability to get accurate throw data at high airflow rates. The ceiling is up to 12 feet high against the Cold Wall on one side, against a raised floor on the other.

We have a full scale Hospital Operating Room set up with our Sterilflo particulate control system (air curtain and downblow panel). We give thanks to Steris for their lighting and operating table donations, which help demonstrate real world velocities at the patient location to assure compliance to ASHRAE 170.

We have a “standard” 2400 cu.ft. Acoustical Demonstration Room (‘In-Situ”) for demonstrating the radiated sound transfer from ceiling plenum located sound sources, such as fan terminals and fan coils. This space has a 3ft deep plenum with open sides, as required by many acoustical demonstration specifications; in addition, we have installed rails and a winch so we can rapidly change out units as requested.

We have an operational Fume Hood Laboratory with several operational variable volume vertical sash fume hoods and Krueger ceiling displacement TAD and RadiaFlo diffusers to demonstrate face velocities at the hoods with full airflow.

We have installed a raised floor against one wall of the double-sided Cold Wall. This raised floor has several different perimeter systems as well as an array of passive interior floor high induction swirl air outlets. The air system is configured to demonstrate displacement ventilation air outlets as well. This room also has several operational chilled beam units in the ceiling and includes a humidifier to show the response of the sensible cooling coils to room humidity levels.

Finally, we have a theater type training room with seating for 40 and power and internet connections for all. This space is conditioned using displacement ventilation.

The entire space surrounding these individual areas, including the workshop, has exposed duct work, which showcase the complex system of space conditioning and laboratory air delivery. All systems are controlled through an internally programmed LabView system with over 50 pressure transducers, several theatrical smoke generators, and connected flat panel monitors with iPad accessible on-screen displays.

We look forward to having many visitors come through to see this new series of spaces for both training and product evaluation, development, and demonstration.

Authored by: Dan Int-Hout, Chief Engineer Krueger