Laboratory Ventilation

Scott Ward Labconco - Jacob Olson UNL BSM Author

04/03/2018 Added

372 Plays

Description

Those who work in laboratories with occupancy controls and/or who use, intent to use, or select and purchase chemical fume hoods will find this colloquium particularly informative.

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[00:00:05.170]Environmental Health & Safety and the Office of Research
[00:00:07.810]would like to welcome you today to the Laboratory Safety
[00:00:11.530]Colloquium on laboratory ventilation.
[00:00:13.960]We actually have two speakers today.
[00:00:16.730]These colloquia are offered in recognition
[00:00:19.730]of the commitment by faculty and staff at UNL
[00:00:23.220]to assure a safe and healthy environment
[00:00:25.110]for teaching and carrying out your very meaningful research.
[00:00:28.910]So I wanna let you know, we will be passing out
[00:00:32.260]a sign-in sheet, if you could please print
[00:00:35.030]your name, department, and email.
[00:00:39.098]And then, we just had our tornado drill,
[00:00:42.440]so don't need to really worry about that.
[00:00:46.100]There are two surveys, as I mentioned,
[00:00:48.080]because we have two speakers.
[00:00:50.370]We're gonna begin with one, and then we'll go directly into
[00:00:52.860]the second one, and then we'll have questions after that.
[00:00:56.220]So, there is our appropriate safe operating procedure
[00:01:04.550]provided by EHS, and that is in the back
[00:01:10.627]if you want that as a refresher.
[00:01:14.640]So as I mentioned, today's topic is laboratory ventilation.
[00:01:19.590]Our first speaker is Scott Ward.
[00:01:23.610]Scott is here representing Labconco.
[00:01:26.670]He earned a Bachelor of Science in Physical Sciences
[00:01:30.040]from Kansas State University, with majors
[00:01:32.230]in chemistry and biology.
[00:01:33.850]He has been with Labconco for 32 years,
[00:01:37.040]designing laboratory safety ventilation systems
[00:01:39.970]all over the Midwest and Rocky Mountain regions.
[00:01:42.600]He's currently president of the Kansas Laboratory
[00:01:45.490]Education Association, and a member of the KLEA
[00:01:49.130]board of directors, the not-for-profit group
[00:01:51.720]responsible for continuing education credit programs
[00:01:54.870]for the state of Kansas laboratory employees.
[00:01:58.610]And our second presenter is Jacob Olson,
[00:02:01.752]here from Facilities Maintenance & Operations.
[00:02:05.860]Jake earned a B.S. in Mechanical Engineering
[00:02:08.330]from here, at UNL.
[00:02:09.960]He has worked at UNL for over 15 years
[00:02:13.120]with Facilities Maintenance & Operation.
[00:02:15.050]He is a Facilities Manager and Controls Engineer
[00:02:18.680]responsible for control engineering and design,
[00:02:21.660]controls operation, electronic, manufacturing,
[00:02:24.864]and building recommissioning programs.
[00:02:27.400]So Scott, welcome to UNL, and Jake,
[00:02:30.240]thank you. Welcome to our colloquium.
[00:02:34.150]Thank you very much, Elizabeth.
[00:02:37.640]For those of you who are not familiar with Labconco,
[00:02:39.710]we're a Kansas City firm.
[00:02:40.940]We manufacture all of our ventilation products
[00:02:43.400]in Kansas City, Missouri.
[00:02:46.070]Essentially, we've been manufacturing fume hoods
[00:02:50.050]and other pieces of equipment there since 1924.
[00:02:55.250]I like to start off with this, just to give you an idea
[00:02:57.990]of the lifespan of the laboratory fume hood industry
[00:03:04.100]here in the United States.
[00:03:06.770]1936, we started manufacturing
[00:03:09.320]the first available productions.
[00:03:13.230]If you see a fume hood like this,
[00:03:15.090]I'll just start this off right away and say
[00:03:17.566]that up until June of 1980 here in the United States,
[00:03:22.940]the vast majority of laboratory fume hoods
[00:03:25.130]that were manufactured by all of the different manufacturers
[00:03:28.760]were made out of a space-age material
[00:03:30.700]that came out in the early 1930s,
[00:03:32.690]manufactured by Johns Manville, and it's a material
[00:03:35.870]called transite asbestos.
[00:03:39.270]So before you drill, screw, move, sand,
[00:03:45.180]or do anything to a laboratory fume hood that looks
[00:03:47.760]anything like that device in the upper right-hand corner,
[00:03:50.840]check with the safety department before you're messing
[00:03:54.140]or moving parts on a laboratory fume hood.
[00:03:57.840]We're located at 8811 Prospect in Kansas City, Missouri.
[00:04:01.750]And I'll start off today with the history
[00:04:03.700]of laboratory fume hoods.
[00:04:06.159]One of my most favorite pictures in my library,
[00:04:11.120]I have a picture for those of you who've ever heard of this,
[00:04:13.100]called the Alchemist.
[00:04:15.885]And my favorite is The Alchemist's Experiment Takes Fire,
[00:04:21.370]giving you an idea of the--
[00:04:24.080]That was painted in 1586, so you know,
[00:04:28.404]laboratory fume hoods have been around for a long time,
[00:04:31.770]and this is just a cut shot of Edison's laboratory.
[00:04:35.830]Well, what are these devices?
[00:04:37.410]These are ventilated enclosures
[00:04:39.100]where you can work with harmful or toxic materials
[00:04:41.410]and handle them safely.
[00:04:43.150]You have to know how to use the laboratory fume hood.
[00:04:45.600]You have to know how the human is supposed
[00:04:47.230]to interact with this device, to do that.
[00:04:50.370]The key thing is, when you see people working
[00:04:54.330]in laboratory fume hoods, why does he not have a mask on?
[00:05:00.470]Sometimes it's hard to get models to put masks on
[00:05:03.310]when they're taking pictures, so you know, we wonder--
[00:05:06.649]PPEs is essentially the primary (laughs) protection device
[00:05:11.500]when you walk into a laboratory, and you should have
[00:05:13.390]all of that on when you're standing in front of a fume hood.
[00:05:16.430]The key word here is "ventilated."
[00:05:18.320]There is an exhaust device on the roof.
[00:05:21.080]When you walk up to a fume hood,
[00:05:23.260]that exhaust device on the roof is pulling air from the room
[00:05:26.745]across the room into the enclosure,
[00:05:31.350]capturing, containing, and removing
[00:05:33.200]whatever's being generated by this piece of equipment,
[00:05:36.930]getting that material behind the baffle and out.
[00:05:40.540]If the exhaust fan's not working correctly,
[00:05:43.160]that's a major-league problem.
[00:05:44.620]Fume hoods are just like airplanes.
[00:05:46.520]There are Bernoulli principles built right into this device.
[00:05:50.840]The air has to go over a surface,
[00:05:52.990]the surface makes the air do something,
[00:05:55.120]and the air makes the material be contained
[00:05:57.530]inside the hood, if used properly.
[00:05:59.820]So if we don't have the proper volume of air
[00:06:01.990]going over a surface, the plane is not going to fly.
[00:06:05.930]And if the plane doesn't fly, you're not gonna be safe.
[00:06:08.910]So in a ventilated device,
[00:06:10.790]we have to take air out of the building.
[00:06:12.590]He's gonna be talking a little bit about the fact
[00:06:15.060]that I can't take air out of the building
[00:06:17.161]if air isn't coming into the building.
[00:06:19.480]So it's a very complex system of sourcing outside air
[00:06:23.700]and exhausting it through the laboratory.
[00:06:26.490]When you're talking to people about laboratory fume hoods
[00:06:29.050]and their function, you wanna use
[00:06:30.350]some certain terminologies.
[00:06:32.190]Capture; when I'm generating something
[00:06:35.010]or I'm boiling a beaker inside of a hood,
[00:06:37.550]you physically see the vapor come off of that beaker
[00:06:39.940]and it starts to move to the back of the hood.
[00:06:42.630]That's called capturing that emission in an air stream.
[00:06:47.700]Containment is a scenario, is a term which is used
[00:06:51.890]when there is a physical barrier
[00:06:53.983]between the human's breathing zone
[00:06:56.380]and the material being generated inside the hood.
[00:07:00.780]Containment means that there's very little chance
[00:07:03.740]that the exhaust system will disrupt
[00:07:07.550]the removal of that effluent air,
[00:07:10.480]you know, you're gonna have a relatively safe scenario
[00:07:13.220]if the sash is down, you're not gonna have to worry
[00:07:15.180]about material ejecting out of the fume hood itself.
[00:07:18.160]So containment is a very important terminology
[00:07:21.450]when you're describing to people
[00:07:22.670]how your fume hood is functioning.
[00:07:25.290]Finally, removal.
[00:07:26.910]Removal is the hardest scenario of all.
[00:07:29.770]I've got to get this material from this point
[00:07:32.515]to the back of the hood, up to the duct work,
[00:07:36.310]out through that duct work, get it to the exhaust blower,
[00:07:39.700]and then I've got to eject that air
[00:07:41.910]above the envelope of the structure that I'm in.
[00:07:46.050]I may be in a one-story building,
[00:07:47.470]I may be in a 10-story building,
[00:07:49.450]but that building has an envelope
[00:07:51.850]as the atmosphere blows over it.
[00:07:53.760]This morning there's a slight breeze;
[00:07:55.730]which direction is it blowing, that's the way
[00:07:58.040]the effluent's gonna go away from my building.
[00:08:00.370]If I don't get it above the rooftop,
[00:08:02.230]if I've got a parapet on the top of the roof,
[00:08:04.410]I'm gonna have turbulence across the roof
[00:08:06.360]and I could eject that air up there
[00:08:08.240]but it could blow right over to the intake of the building
[00:08:10.310]if they're up there, and be brought right back in.
[00:08:12.670]So removal is an extremely important scenario.
[00:08:18.870]Face velocity: you'll hear "face velocity"
[00:08:21.130]used a lot on laboratory fume hoods.
[00:08:24.040]Face velocity is the feet per minute
[00:08:27.030]that air is moving through the opening,
[00:08:30.270]from the work surface, now, a lot of fume hoods
[00:08:32.590]have air foils at the bottom.
[00:08:34.630]We are talking about the work surface
[00:08:36.620]that is under the air foil.
[00:08:38.570]From the work surface to the bottom
[00:08:41.390]of the handle of the fume hood.
[00:08:43.730]When you say "I want an 18-inch opening,"
[00:08:46.040]you do not measure from the air foil, you measure
[00:08:48.380]from the work surface to the bottom of the handle;
[00:08:51.140]boom, that's where I'm supposed to be
[00:08:53.120]and my velocity should be this, okay?
[00:08:56.440]So by using the square footage of the opening
[00:08:59.764]and the volume of air that can be in on the bypass
[00:09:03.070]and under the air foil, we can calculate the volume of air
[00:09:06.530]that a fume hood will use, and make sure
[00:09:09.550]that it's operating properly.
[00:09:12.070]This is the equation for doing that.
[00:09:14.840]Vast majority of it is, what's the square footage
[00:09:16.920]of the opening, from the work surface
[00:09:18.710]to the bottom of the handle, multiplied by the speed;
[00:09:21.950]that gives you a cubic foot per minute
[00:09:23.700]being exhausted from that hood.
[00:09:25.840]Why is that important?
[00:09:27.670]In Lincoln, Nebraska, let's just say
[00:09:29.710]I've got a five-foot fume hood.
[00:09:30.920]Here's a four-foot fume hood, it uses 750 CFM.
[00:09:34.600]A five-foot fume hood uses a thousand cubic feet
[00:09:37.020]of air per minute to do its function.
[00:09:40.120]In this ZIP code, if I exhaust a thousand cubic feet of air
[00:09:43.890]through a fume hood, 24/7, 352,
[00:09:46.964]all the days that I'm running,
[00:09:49.540]it will be eight dollars a cubic foot of air
[00:09:52.410]exhausted out of the building,
[00:09:53.650]that's how much the electricity will cost
[00:09:56.050]just to make it comfortable for you to stand in the room.
[00:10:01.280]So for every five-foot fume hood on this campus
[00:10:04.150]and on the center campus, you're looking
[00:10:06.390]at eight thousand dollars a year in consumption,
[00:10:09.365]which is why his job is really important.
[00:10:12.720]If you look at all the rooftop exhausters in this building
[00:10:15.757]and if you can--
[00:10:17.090]Anybody know how many fume hoods are on both campuses?
[00:10:21.470]I'll bet it's a lot. (laughs)
[00:10:24.330]I don't know how many it is, but it's gotta be a lot.
[00:10:27.400]And if you imagine the average-size fume hood
[00:10:29.650]is a six, that's the most favorite,
[00:10:31.740]it's not too tough to figure that, you know,
[00:10:34.570]tuitions are gonna go up if we don't find a way
[00:10:36.870]to have people using laboratory fume hoods
[00:10:39.320]appropriately on the campus.
[00:10:42.620]Air foil, this is the Bernoulli device
[00:10:46.470]that's at the bottom of the sash pull;
[00:10:48.530]if I take the sash and close it completely
[00:10:50.709]I'm touching the air foil,
[00:10:52.740]I'm using the Bernoulli principle.
[00:10:55.150]As air moves over this surface, it speeds up.
[00:10:58.800]The air speeding up on this surface
[00:11:03.340]is designed so that it deflects that air down
[00:11:06.080]to a location six inches inside the glass of the fume hood.
[00:11:09.870]So if I'm standing there operating the glass sash
[00:11:12.070]of a fume hood, if I close it all the way to the air foil
[00:11:15.780]and then just make a pencil mark
[00:11:17.770]and I measure inside the fume hood six inches,
[00:11:20.980]that is where the air foil is designed to push the air
[00:11:24.470]on any fume hood that has an air foil.
[00:11:27.340]And I'll get into why in just a moment.
[00:11:29.440]It's important to know where that six-inch position
[00:11:32.530]inside the fume hood actually is.
[00:11:35.710]The sash, it needs to be transparent,
[00:11:37.990]it needs to be able to be cleaned,
[00:11:40.870]and it needs to be resilient to whatever
[00:11:42.850]you're using inside the fume hood.
[00:11:45.240]If you're doing preps with hydrofluoric acid,
[00:11:47.980]you do not want a glass sash.
[00:11:50.200]Hydrofluoric acid actually can damage
[00:11:53.545]regular borosilicate and laminated glass.
[00:11:58.510]It'll cloud it to the point that you can't see through it.
[00:12:01.700]The sash needs to remain transparent
[00:12:04.010]so that you can close the sash and visually see
[00:12:06.480]what's going on inside the hood from across the room.
[00:12:09.460]If the sash gets so dirty that you can't see
[00:12:11.590]what's going on inside, it needs to be cleaned.
[00:12:15.100]One of the safety issues right now is,
[00:12:17.360]how do I clean the back side of this sash?
[00:12:20.170]Anybody tried that?
[00:12:25.220]I've tried it.
[00:12:26.750]You get a sponge, and you reach in here
[00:12:28.820]and you start washing off the bottom;
[00:12:31.269]the liquid's dripping right here
[00:12:33.650]onto the center of your elbow.
[00:12:36.350]Does that liquid have hydrofluoric acid on it?
[00:12:38.939]I don't know.
[00:12:40.750]But I get to the top, I can't get to the top six inches
[00:12:43.940]because I have to pull the sash down to see it.
[00:12:47.530]There are devices called sash gliders now
[00:12:49.870]where you can put the decon solution inside the fume hood,
[00:12:52.300]put it on one half, the other's a supermagnet.
[00:12:57.141]So you can decon the inside of your fume hood
[00:12:59.850]and not come in contact with the solution
[00:13:02.000]that you're using as a decon,
[00:13:04.210]and at the same time, you can clean the entire sash.
[00:13:06.920]For those of you who deal with biological safety cabinets,
[00:13:09.620]this is a real godsend.
[00:13:12.490]So you can find those in all
[00:13:14.640]of the scientific laboratory magazines.
[00:13:18.560]Sashes can be tempered safety glass, which is what you see
[00:13:22.310]everybody going to now, or they can be the old-style
[00:13:25.320]laminated safety glass.
[00:13:27.050]Be careful about what you're doing
[00:13:28.430]in laboratory fume hoods that have laminated safety glass.
[00:13:31.280]If you have an explosion in that hood,
[00:13:33.300]you're gonna have very large pieces of glass
[00:13:35.140]coming away from the fume hood.
[00:13:36.980]So think about what you're setting up
[00:13:38.540]in your laboratory fume hood, and look
[00:13:40.510]at how old the design is.
[00:13:42.320]You can actually tell laminated safety glass
[00:13:44.762]from tempered safety glass.
[00:13:47.280]Tempered safety glass breaks in a rock salt configuration
[00:13:50.091]which is dimensioned on the thickness of the glass.
[00:13:52.880]3/16th-inch glass, 3/16ths-inch cube.
[00:13:56.960]You may not look really good after an explosion,
[00:14:00.680]but you won't have any large lacerations.
[00:14:04.330]So be careful about the materials of construction
[00:14:06.770]in these devices.
[00:14:08.880]You can have all kinds of complex types of sashes.
[00:14:13.170]These all came about from the fact that air got expensive.
[00:14:17.354]The specification on air consumption
[00:14:20.230]on this fume hood with horizontal sliding sashes
[00:14:22.330]is essentially, how big an opening can I get?
[00:14:25.660]This fume hood uses less air than one like this,
[00:14:29.230]unless I put a sash stop on it,
[00:14:31.250]which you'll see on most fume hoods now.
[00:14:33.320]This is the safer fume hood;
[00:14:35.140]there are fewer moving parts to be disrupted.
[00:14:37.840]You're gonna have a more sustainable fume hood.
[00:14:40.970]Be careful about fume hoods with adjustable baffles
[00:14:43.970]that are required to make them function.
[00:14:47.110]If a knob comes off or a component is dislodged,
[00:14:50.667]the plane won't fly.
[00:14:52.120]If you've ever played with a glider
[00:14:53.630]and you set that thing up wrong,
[00:14:55.320]boom, it does a nose dive into the ground.
[00:14:57.820]The exact same thing happens
[00:14:59.270]with laboratory fume hoods on adjustable baffles.
[00:15:02.420]The inside liner material is important.
[00:15:04.630]You've gotta have something that's resilient
[00:15:06.400]to the material you're working with.
[00:15:08.920]Reduced air volume was a technique
[00:15:10.840]which essentially promoted the controls industry.
[00:15:14.670]It was used on variable air volume fume hoods,
[00:15:17.970]as they change the air flow going through the fume hood.
[00:15:21.760]This is a variable air volume fume hood.
[00:15:23.730]It shows a control system with a presence sensor.
[00:15:27.170]As the sash goes up, the damper opens up,
[00:15:33.080]as the sash comes down, the damper closes down,
[00:15:36.550]and you've got a possible presence sensor,
[00:15:40.440]a control box, and a valve.
[00:15:42.520]As the sash is going up and down, this device
[00:15:44.820]is controlling and maintaining a very simple speed.
[00:15:48.600]Hundred feet per minute here, hundred feet per minute here,
[00:15:51.000]hundred feet per minute here, but the volume has to increase
[00:15:54.240]to maintain that constant velocity.
[00:15:56.960]These systems get very complicated,
[00:15:59.356]but you must have supply air coming in
[00:16:02.520]for every fume hood exhaust that you've got.
[00:16:05.430]In 1998, right about that location,
[00:16:10.670]Lawrence Berkeley Laboratories let out a request
[00:16:14.500]for fume hood manufacturers to help with a new design
[00:16:17.070]called a high-performance laboratory fume hood.
[00:16:19.970]This is what it looked like.
[00:16:21.450]It had motor blowers on the air foil
[00:16:24.751]and on the front cover of the hood,
[00:16:27.210]and it literally blew air to the back of the hood.
[00:16:31.550]This essentially, we worked with them,
[00:16:33.380]we build those hoods for them,
[00:16:35.330]but one of the things we learned was,
[00:16:36.780]we didn't wanna use a motor blower.
[00:16:38.980]You don't want three motor blowers, depending
[00:16:41.170]on whether or not your fume hood is gonna fly correctly.
[00:16:43.790]And this is essentially the design that we created,
[00:16:47.830]where there are no moving or metal parts
[00:16:50.710]inside this fume hood.
[00:16:52.320]So a traditional fume hood has an air flow;
[00:16:54.610]as the air comes in, you'll see vortices forming
[00:16:57.040]in the top of the fume hood.
[00:16:59.660]On the newer, higher-performance designs,
[00:17:03.220]you'll see a more laminar flow of air.
[00:17:05.360]You're starting to see holes on the baffle of these hoods,
[00:17:09.440]and the air comes down, so you see a descending flow.
[00:17:13.350]This is a classic air flow design
[00:17:16.060]of a classic liner fume hood.
[00:17:19.868]Oops, sorry.
[00:17:30.370]And here's the vortex that forms in the top of the hood.
[00:17:33.580]This dwell pattern forming in the top of a fume hood
[00:17:36.920]is why fume hoods lose containment
[00:17:38.800]when people walk by them, or if you're standing
[00:17:41.220]in front of a fume hood improperly.
[00:17:44.110]This is what the air flow looks like
[00:17:45.770]on a properly designed capture.
[00:17:47.770]You should see a slight descension
[00:17:49.410]toward the rear of the hood.
[00:17:50.890]If the human face is right here,
[00:17:52.530]you can see that we're taking the straightest line
[00:17:54.800]away from the breathing zone of the human.
[00:17:58.510]There are various types of special purpose hoods.
[00:18:01.450]Consult the EH&S group, depending on
[00:18:04.440]what you're working with:
[00:18:05.273]radioisotopes; special types of acid
[00:18:08.320]like perchloric acid; and there's a new material
[00:18:10.380]called piranha solution.
[00:18:12.546]Wait'll you, anybody here, works with that.
[00:18:15.964]You're lucky. (laughs)
[00:18:18.410]Start studying up, any of the materials laboratories
[00:18:23.163]are going to have that material showing up pretty soon,
[00:18:27.650]so you guys might wanna do some discovery work
[00:18:31.720]on piranha solution.
[00:18:33.430]So that's how the device functions.
[00:18:36.930]Now, how can we think about approaching this device?
[00:18:40.110]Number one, we have to understand the hazard
[00:18:42.100]that we're working with.
[00:18:42.970]You need to read the SDS sheets,
[00:18:46.120]I used to call 'em MSDS sheets,
[00:18:48.210]but understand what you're working with.
[00:18:50.550]These documents change constantly.
[00:18:52.830]I can't tell you, over the last 30 years
[00:18:54.740]while I've been at Labconco, how many times
[00:18:56.745]the data sheet for formaldehyde has changed.
[00:19:01.520]We used to spend our lives immersed in it up to the elbow
[00:19:05.060]and now, oh my gosh, you know?
[00:19:08.370]So be very careful with the chemical substances
[00:19:10.550]you're working with, and understand what they are
[00:19:12.884]and keep abreast of what they're turning into.
[00:19:16.180]You need to operate the fume hood
[00:19:17.530]at or above a recommended threshold limit,
[00:19:19.730]and by the way, these bullet points
[00:19:21.490]should be on every single fume hood.
[00:19:23.640]Fume hood manufacturers here in the United States
[00:19:25.790]have to put this on a fume hood.
[00:19:28.290]So this is, you can read it yourself
[00:19:30.840]and keep yourself abreast of this.
[00:19:33.470]Operate the fume hood at a recommended threshold value.
[00:19:36.230]Talk to the EH&S people and they can tell you.
[00:19:38.300]That means probably a higher face velocity
[00:19:40.410]for certain applications.
[00:19:42.250]You wanna keep the sash as low as possible,
[00:19:44.270]you wanna maintain a physical barrier
[00:19:46.000]between you and what's going on inside the fume hood.
[00:19:48.690]That's typically an inch and a half
[00:19:50.270]to two inches below your chin,
[00:19:52.486]so you can comfortably approach and work with stuff.
[00:19:55.400]You don't want the sash so low
[00:19:56.810]that you're taking an unergonomic stance
[00:19:59.800]and approach to your work, you're gonna generate
[00:20:01.620]more accidents and possibly hurt yourself.
[00:20:04.000]So you wanna make sure that you've got
[00:20:05.160]the proper sash position.
[00:20:06.920]You wanna keep apparatus six inches inside the air foil.
[00:20:10.480]So here's the magic.
[00:20:11.870]This is why everybody tries to get the air to hit
[00:20:15.410]six inches inside the glass sash.
[00:20:17.998]When you put a five-foot nine mannequin
[00:20:20.100]in front of a laboratory fume hood
[00:20:21.470]and create a 100 foot per minute face velocity,
[00:20:23.530]the air's gotta go around the mannequin
[00:20:25.220]to get into the hood.
[00:20:26.710]That's exactly what you're doing when you present yourself
[00:20:29.160]in front of a laboratory fume hood,
[00:20:30.570]you reach into the fume hood.
[00:20:32.320]As the air goes around your body,
[00:20:34.490]you create a distortion pattern
[00:20:37.900]and it comes right back on the median of the torso,
[00:20:41.040]so this diameter of vortices that's created
[00:20:45.040]by you standing in front of a fume hood
[00:20:47.030]will be nine inches in diameter
[00:20:48.630]at a hundred feet per minute.
[00:20:50.900]When you're standing in front of a laboratory fume hood
[00:20:52.950]the fume hood should be designed
[00:20:54.743]so that your nose is three inches away from the glass sash.
[00:20:58.720]Three plus six is nine.
[00:21:03.290]That's the whole equation to working
[00:21:04.910]inside of a laboratory fume hood.
[00:21:06.810]If you get closer than that, the turbulence envelops,
[00:21:11.240]if I'm boiling something in a fume hood
[00:21:13.060]or if I'm mixing chemicals, and I'm standing here
[00:21:15.620]trying to work, I envelop and dwell that material
[00:21:19.460]and it comes up into my breathing zone.
[00:21:21.700]I wanna set the material in and take a stance at that
[00:21:25.930]so that I am farther than nine inches
[00:21:28.680]away from this front edge.
[00:21:31.400]If you do that, you'll see that you have
[00:21:33.140]a substantially higher success rate
[00:21:35.430]in ventilating that generated material
[00:21:38.090]and not winding up ingesting it or breathing it in.
[00:21:41.860]So work six inches inside the fume hood.
[00:21:45.120]Be aware that a laboratory fume hood
[00:21:47.457]is just like an airplane.
[00:21:50.540]If I load enough ice onto the wings of a plane,
[00:21:54.920]the plane will not fly.
[00:21:57.230]If I load enough equipment into a laboratory fume hood
[00:22:00.640]so that I can't sweep that air
[00:22:02.270]to the back of the work surface,
[00:22:04.200]I am not going to be able to accomplish that mission.
[00:22:06.940]Air comes in, it strikes here, it dwells here.
[00:22:10.460]It's within six inches of the opening.
[00:22:12.660]I stand in front of the fume hood
[00:22:13.797]and the material comes right back into my face,
[00:22:16.120]and the higher I turn the air flow exhaust up,
[00:22:19.570]the worse that scenario becomes,
[00:22:21.510]because this turbulence gets bigger
[00:22:23.700]with the acceleration of the face velocity.
[00:22:27.030]So faster is not better.
[00:22:29.250]You do not wanna remove any parts from the fume hood.
[00:22:32.040]If you walk in and the fume hood baffle's been removed,
[00:22:34.520]for goodness sakes, you know,
[00:22:36.601]call the EH&S people.
[00:22:39.970]Minimize traffic in front of the fume hood,
[00:22:42.770]minimize traffic walking behind you
[00:22:45.160]when you are in the fume hood.
[00:22:46.940]If somebody walks past you,
[00:22:48.870]they're moving at about 200 feet per minute
[00:22:51.140]through the atmosphere, that wave envelops you,
[00:22:54.380]this turbulence gets larger
[00:22:56.310]and then pulls material out of the hood
[00:22:58.080]while you're standing there working.
[00:22:59.360]So don't let people walk behind you
[00:23:01.830]when you're working in a laboratory fume hood.
[00:23:04.260]You guys already do an excellent job
[00:23:06.170]of providing routine maintenance
[00:23:08.210]and the scheduled testing for your laboratory.
[00:23:13.160]This next video will show you how to evaluate
[00:23:19.700]your own fume hood visually, okay?
[00:23:27.500]If it turns on.
[00:23:31.277](upbeat music)
[00:23:35.940]In our manuals, we recommend that this be done every time
[00:23:38.540]you move a piece of equipment inside the fume hood
[00:23:41.100]or place another piece in. A laboratory fume hood
[00:23:42.917]is a ventilated enclosure where harmful materials
[00:23:44.760]can be handled safely. We also recommend
[00:23:46.202]that this get done once a week, on Fridays.
[00:23:48.080]Air flows into the hood to capture and contain
[00:23:49.617]contaminants, preventing their escape into the laboratory.
[00:23:53.540]Smoke tests provide a visual inspection
[00:23:55.740]of the hood's ability to contain fumes generated inside.
[00:23:59.680]With the sash in the raised position,
[00:24:01.760]smoke is exhausted evenly from all areas of the hood.
[00:24:05.990]Aerodynamically designed components, such as the sash foil,
[00:24:10.010]vertical fascia, baffle, and liner
[00:24:13.240]enhance the hood's ability to capture fumes.
[00:24:15.840]Be very careful about what you use
[00:24:17.360]to visualize this containment.
[00:24:19.550]You can contaminate the inside of your hood
[00:24:22.280]with things that you can't get back out.
[00:24:23.660]The bypass hood is designed
[00:24:25.110]to minimize the fluctuations Don't go out
[00:24:27.144]to the fireworks stand and buy in face velocity as the sash
[00:24:28.490]is lowered or raised. some pyrotechnic smoke bombs
[00:24:30.455]and set 'em off inside your fume hood.
[00:24:33.088]Like this guy did. Air enters the hood
[00:24:35.056]through openings along the top of the hood
[00:24:36.131]and underneath the air foil,
[00:24:37.786]even when the sash is in the fully closed position.
[00:24:41.010]The baffle directs the air to follow
[00:24:42.880]specific flow patterns within the hood
[00:24:45.130]and also generates a uniform velocity of air.
[00:24:49.560]Fumes generated near the work surface
[00:24:51.500]are drawn in through the lower opening.
[00:24:53.820]The baffle, in conjunction Robust containment.
[00:24:56.558]With the sash foil, directs the air currents
[00:24:57.391]to sweep the work surface. That's what you're seeing
[00:24:58.990]right there. On hoods with open slots
[00:25:01.364]along the edges of the baffle, fumes generated
[00:25:03.350]in the middle of the hood are drawn in from the sides.
[00:25:07.130]Many conditions affect the efficiency and safe operation
[00:25:10.130]of any hood. That lab tape is exactly
[00:25:11.786]at the six-inch position. For maximum containment,
[00:25:14.084]work should be performed at least
[00:25:15.722]six inches inside the hood.
[00:25:18.000]Large apparatus or clutter inside the hood
[00:25:20.810]can obstruct the air flow and allow fumes to escape.
[00:25:25.090]Apparatus should be elevated on blocks
[00:25:27.140]to allow air to flow under it.
[00:25:29.010]Number 10 rubber stopper--
[00:25:31.183](crosstalk drowns speaker) Abrupt movements can cause
[00:25:32.762]turbulence, allowing fumes to escape.
[00:25:34.740]The sash should be lowered or raised gently.
[00:25:39.550]Location is important for optimal hood performance.
[00:25:43.090]The hood should be located away from windows, doors,
[00:25:46.380]ceiling air diffusers, heat registers,
[00:25:49.380]or fans that alter the air patterns in the laboratory.
[00:25:52.070]Did you just see the disruption
[00:25:53.530]of that line? Personnel walking by
[00:25:54.910]can disrupt the air flow, That creates dwell.
[00:25:56.200]Dwell is dangerous.
[00:25:58.013]So the hood should be installed
[00:25:59.220]in a low-traffic area.
[00:26:01.400]Lowering the sash lessens the effect
[00:26:03.500]of traffic and other external
[00:26:05.060]air flow disturbances. Dry ice and warm water
[00:26:07.097]is the easiest way to evaluate your hood
[00:26:09.636]To get the maximum performance from this
[00:26:11.054]important piece and not contaminate
[00:26:12.070]the inside of it. of laboratory safety
[00:26:13.331]equipment, it is important to understand the design
[00:26:15.600]and proper operation of your laboratory hood.
[00:26:18.730]By knowing how it functions most efficiently,
[00:26:21.550]you can ensure that your lab safety ventilation system
[00:26:24.250]is effectively protecting you
[00:26:25.827]and your important work.
[00:26:29.257](upbeat music) Labconco.
[00:26:38.505]So that guy did something that I tell everybody not to do.
[00:26:42.480]Never walk away from a laboratory fume hood
[00:26:44.770]with the sash up.
[00:26:46.460]The sash should be closed
[00:26:48.130]before you step away from the laboratory fume hood.
[00:26:51.070]Present a physical barrier so that if something goes off
[00:26:53.840]from the work that you started,
[00:26:55.490]it's not gonna involve everybody else in the room,
[00:26:57.960]or the instrumentation, or, you know,
[00:27:01.110]the other parts of the lab.
[00:27:02.790]So accessories, I'm not gonna go into this
[00:27:06.850]really too deeply, I'm extending out here.
[00:27:09.000]The one thing I do wanna point out is
[00:27:11.200]laboratory fume hood placement in the laboratory.
[00:27:13.764]If you're putting a laboratory in
[00:27:16.681]or a new fume hood in, make sure that the opening
[00:27:20.380]of the fume hood is involving the lowest square footage
[00:27:24.120]possible in the space.
[00:27:25.880]This is called the zone of involvement.
[00:27:27.760]If something explodes in this hood or a fire starts,
[00:27:30.730]things are gonna go this way.
[00:27:32.080]If you put the fume hood here and you're trying
[00:27:34.060]to walk away from a fume hood,
[00:27:36.010]it's going to follow you out.
[00:27:37.680]The fume hood should always be placed in a position
[00:27:40.150]where your immediate step to the door
[00:27:42.420]is at a 90-degree angle to the hood space.
[00:27:47.560]So when you're trying to think about a laboratory fume hood,
[00:27:51.590]look at what you're going to be using
[00:27:52.930]and read the chemical SDS sheets.
[00:27:55.810]Identify what types of accessories, what local codes,
[00:27:59.090]your EH&S people can help you with that,
[00:28:01.220]and whether or not you might need
[00:28:03.407]to work with an ADA-type application.
[00:28:06.080]Finally, lower explosive limits:
[00:28:08.017]"I'm working with a liter of acetone,
[00:28:09.877]"I need an explosion-proof fume hood."
[00:28:12.040]No.
[00:28:13.180]Acetone has a very low flammability rating
[00:28:16.940]with respect to materials like ether.
[00:28:19.200]You can have liters upon liters of acetone in a fume hood
[00:28:22.810]and not reach the lower explosive limit.
[00:28:25.110]It only takes 29 cubic feet of air
[00:28:27.250]going through a fume hood, a six-footer,
[00:28:29.780]to keep the flammability rating inside that hood
[00:28:33.380]below a 25% lower explosive limit.
[00:28:36.270]So let the EH&S people help you.
[00:28:39.520]You do not necessarily need to--
[00:28:41.380]I get, I bet this happens 20 times a week
[00:28:44.287]where somebody thinks they need the lower explosive limit
[00:28:47.170]and the explosion-proof fume hood from working with alcohol.
[00:28:58.299]Thank you.
[00:29:00.312](clapping)
[00:29:04.810]So while Jake steps up,
[00:29:06.451]I'm going to let you know,
[00:29:07.763]Sorry, ma'am, I ran a little long.
[00:29:08.752]That's okay. We ran into a last-minute
[00:29:10.290]issue with the sound in this room,
[00:29:12.670]so if you didn't hear well, that video and its commentary
[00:29:18.430]will be in the recording that we put online,
[00:29:22.560]and also, in addition, those of you who put your email
[00:29:27.340]on there, I will email that out separately
[00:29:30.120]within the next week so that you can review.
[00:29:33.330]I'll link to that video,
[00:29:35.730]and it just happened today, so sorry.
[00:29:41.880]Well, hello, welcome.
[00:29:44.500]So I'm here to talk about my favorite topic,
[00:29:46.640]is ventilation and controls.
[00:29:49.321]Like you said, I'm Facilities Manager
[00:29:52.430]and Controls Engineer for the university here.
[00:29:57.250]First I wanna talk about laboratory ventilation.
[00:30:01.570]So I kinda wanna start off, every lab is different.
[00:30:06.300]There's positive rooms, negative rooms,
[00:30:09.300]all kinds of different uses,
[00:30:10.960]really depends on the research that you're doing.
[00:30:13.940]But basically, the ventilation is a balance
[00:30:17.640]of supply and exhaust air into the lab.
[00:30:21.060]So, majority of the labs here on campus
[00:30:24.050]are based on a constant air flow offset.
[00:30:29.682]Basically, the balance of supply air going in
[00:30:32.300]and the exhaust air going out
[00:30:33.880]is always trying to maintain a constant difference.
[00:30:37.800]So if you've got an exhaust that is higher than the supply,
[00:30:42.200]it's a negative pressure; if the supply is greater
[00:30:45.120]than the exhaust, it's a positive pressure.
[00:30:47.130]Now that would be, typically, clean rooms.
[00:30:50.601]Lab ventilation rates are in terms
[00:30:53.300]of air changes per hour, or ACH.
[00:30:56.470]So unoccupied labs typically operate
[00:30:59.570]at four air changes per hour,
[00:31:02.470]whereas occupied labs can operate
[00:31:05.491]typically, at a minimum, between six and 10
[00:31:08.780]air changes per hour.
[00:31:12.520]So basically, the air change is the volume of this room,
[00:31:15.660]I need to change this out six times in one hour.
[00:31:20.270]They range, some we've got higher.
[00:31:23.570]I've seen very high, almost a hundred air changes per hour
[00:31:26.750]in certain laboratories, just based
[00:31:29.500]on how they're operating.
[00:31:31.840]It really depends on how many fume hoods you have;
[00:31:34.780]I mean, if you've got a bunch of fume hoods
[00:31:36.330]in a small room, you're gonna have a large amount of exhaust
[00:31:40.040]and you gotta make up that air.
[00:31:41.490]That just increases the air changes.
[00:31:45.130]So then also, when I talked about the six to ten minimum,
[00:31:49.240]as a room needs more cooling
[00:31:52.207]your ventilation rate will increase to add more cooling,
[00:31:55.660]more air into the room.
[00:32:01.490]Alright, so the question is, how do we know
[00:32:04.230]when a lab is occupied or unoccupied?
[00:32:06.960]So, in a majority of the laboratories on campus,
[00:32:10.510]we have installed a lab occupancy switch.
[00:32:14.680]So many of you may have seen this.
[00:32:17.900]So it's a simple button on the wall,
[00:32:20.000]usually by each entrance into the lab, or centrally located.
[00:32:24.540]It's just got a "start" and a "stop" button.
[00:32:27.680]So when you push the "start" button,
[00:32:31.102]that means the lab's in use, the light will turn on,
[00:32:35.443]and you push the "stop" button when the lab's not in use,
[00:32:38.830]light will turn off.
[00:32:40.210]Pretty simple.
[00:32:42.080]So as I said before, when a lab is in use
[00:32:46.240]our minimum air changes are around that six to 10.
[00:32:50.587]And we control the temperature of the room
[00:32:53.750]to plus or minus one degree,
[00:32:56.500]so pretty tight control, we try to.
[00:33:00.000]When a lab's not in use, we back that down
[00:33:03.660]to about four air changes, or as low as we can.
[00:33:07.110]There's certain situations that don't let us go any lower.
[00:33:11.340]And we let the temperature drift
[00:33:13.830]plus or minus three degrees.
[00:33:15.880]So that push button on the wall really tells us
[00:33:19.360]how you're operating your lab.
[00:33:25.280]So next we've got fume hood controls.
[00:33:28.620]Now, I should probably start off with
[00:33:30.700]that the control system here at the university,
[00:33:33.910]we develop that all in-house,
[00:33:35.720]so we make the thermostat on the wall,
[00:33:39.283]the digital ones, the newer ones.
[00:33:43.240]We make the fume hood controllers
[00:33:45.910]and all the control components.
[00:33:47.690]We actually build the circuit boards here on campus.
[00:33:51.470]So this fume hood controller,
[00:33:57.135]we've got 463 of these in operation.
[00:34:02.960]There's probably about, total of 750 fume hoods on campus.
[00:34:08.600]It can control constant volume or variable volume hoods,
[00:34:12.500]so the difference is, as the previous presenter kinda said,
[00:34:18.550]we try and maintain a constant face velocity all the time.
[00:34:24.570]Now, there's a type of hood that is constant volume,
[00:34:28.140]so no matter how you move that sash up and down,
[00:34:31.230]it's always trying to achieve that same air flow rate
[00:34:34.057]as well as a constant face velocity.
[00:34:37.620]They do that by, it's usually a bypass,
[00:34:40.810]so as you move that, it kinda opens up other,
[00:34:42.840]or as you close it, it opens up other airways
[00:34:45.610]so that air can get in, so it keeps that air flow constant.
[00:34:48.690]Versus the variable volume is, that air flow changes
[00:34:53.130]as you move that sash up and down.
[00:34:56.360]But it still always maintains a constant face velocity.
[00:35:04.210]So our fume hood controller monitors that sash position
[00:35:09.200]and air flow going through, and there's a valve
[00:35:13.120]up above the ceiling on most fume hoods that it controls.
[00:35:22.880]So here's the face of that fume hood controller.
[00:35:27.270]You've got the top, face velocity display,
[00:35:31.030]so that's gonna show you your actual
[00:35:33.530]face velocity that it's measuring.
[00:35:36.680]You've got, the black button on the right
[00:35:39.610]is an "on" and "standby" button
[00:35:41.300]and I'll tell you about that in a little bit.
[00:35:43.180]You've got "alarm mute" button
[00:35:44.950]in the middle, the gray button,
[00:35:46.560]an "emergency" button, and a flow status indicator.
[00:35:52.860]So normal operation
[00:35:55.720]to turn on a hood, you push that black button to turn it on.
[00:36:02.196]The "on/standby" button will illuminate,
[00:36:05.900]the face velocity will be displayed,
[00:36:08.602]and the flow status indicator will turn green,
[00:36:12.230]assuming the proper airflow can be achieved.
[00:36:17.975]Next, standby mode.
[00:36:21.110]So that means your hood's not in use.
[00:36:23.990]You push that black button again to release it.
[00:36:28.300]It goes into a mode where it clears out the LCD screen
[00:36:33.430]and the flow indicator will flash red, green.
[00:36:40.450]Alright, talking about standby mode,
[00:36:42.890]so what does it mean, standby?
[00:36:45.690]So that means the hood is not in use.
[00:36:49.620]There's no chemicals in there and
[00:36:52.120]the exhausted air will go down to a minimum air flow,
[00:36:57.200]minimum that's allowable.
[00:37:00.751]And again, every lab and hood is different.
[00:37:04.760]There are a lot of variables that determine how low we can go.
[00:37:07.670]It could be the size of the air valve,
[00:37:09.220]that we can only measure so far,
[00:37:11.450]or just the size of the fume hood itself.
[00:37:18.360]Fume hood alarm:
[00:37:20.120]so if there's not proper air flow in your fume hood,
[00:37:23.607]the fume hood controller will trigger an audible alarm
[00:37:26.918]and the flow status indicator will turn red,
[00:37:30.010]kinda as you see it there.
[00:37:31.530]So it'll show the real face velocity there,
[00:37:34.300]like that 40 up there.
[00:37:37.349]You should never see a fume hood at 40. (laughs)
[00:37:39.850]But your red light, your flow indicator light
[00:37:42.660]will turn red, it'll be audible.
[00:37:47.080]So what do you do when that happens?
[00:37:50.490]Properly put away your experiment,
[00:37:52.430]'cause something's wrong. (laughs)
[00:37:55.750]Close your sash; this is where you can use
[00:37:59.040]that "mute" button, so since that's just alarming at you
[00:38:02.420]in your face, once you've completely taken down
[00:38:06.370]your experiment or closed the sash up,
[00:38:08.980]hit that "mute" button. And you need to call Facilities
[00:38:11.940]'cause there's something wrong.
[00:38:12.860]Could be the system, it could be the air valve up there,
[00:38:15.690]could be various things that's causing that.
[00:38:22.230]Emergency mode:
[00:38:23.380]So what do you do if you spill something bad,
[00:38:27.405](laughs) hazardous chemical, in the hood?
[00:38:31.062]You push that red "emergency" button.
[00:38:33.270]That will take the fume hood exhaust valve all the way open.
[00:38:37.640]It'll go full exhaust.
[00:38:41.210]You close that sash, and you call EH&S.
[00:38:47.930]The emergency mode, like I said,
[00:38:49.380]it sets it to a maximum flow.
[00:38:51.660]It just opens that valve all the way up,
[00:38:53.580]ignores all set points, ignores the sash position,
[00:38:56.730]all that stuff.
[00:39:01.590]So a few other things we've got around.
[00:39:03.690]Some of the older hoods, they don't have a control valve
[00:39:05.710]up in the ceiling or in the duct work.
[00:39:08.730]We went through and installed a bunch of gauges,
[00:39:12.020]just to give the user something to look at,
[00:39:14.960]some indication, "Hey, is my fume hood working?"
[00:39:17.720]If we are not doing a little test with some smoke
[00:39:21.370]or the dry ice and warm water,
[00:39:26.030]you gotta know if it's working.
[00:39:28.180]So we install these pressure gauges
[00:39:29.540]that kinda tell you there is flow.
[00:39:33.420]A lot of the older hoods, they might just have a single fan,
[00:39:36.280]it might be a toggle switch on the hood.
[00:39:41.430]But the pressure gauge indicates there is flow.
[00:39:45.740]So if it says zero, probably you shouldn't use it. (laughs)
[00:39:49.860]Let's just say, don't use it if it says zero.
[00:39:54.760]And here's kinda, tying on with the previous presenter,
[00:40:00.320]laboratories and energy use.
[00:40:02.480]So all of our lab controls are there for safety
[00:40:07.010]and for energy management.
[00:40:09.170]So the labs are the highest energy cost on campus.
[00:40:14.602]Since we're the university, we get a really discounted rate
[00:40:17.940]on electricity, so the regional is probably eight dollars
[00:40:22.720]per CFM; we're only paying about
[00:40:25.510]three to four dollars per CFM.
[00:40:28.000]So that means your average six-foot hood
[00:40:31.730]is costing about $2,000 or more.
[00:40:34.390]That's the size of a house, that's the amount of energy
[00:40:36.910]of a house, for an entire year.
[00:40:40.180]So that's why it's very important to close those sashes,
[00:40:43.820]utilize the standby mode,
[00:40:46.430]because they have a huge impact on energy costs.
[00:40:50.547]And then proper use of those laboratory occupancy switches
[00:40:54.432]can save 50% or more on our energy costs.
[00:41:02.360]That is all I have; short and sweet.
[00:41:04.530]We do have time for some questions.
[00:41:07.290]To get your question as well as the answer on the video,
[00:41:10.921]if you have a question, raise your hand
[00:41:12.010]because you have to talk into the mic,
[00:41:13.210]even though sound doesn't go over the room.
[00:41:16.160]So does anyone have any questions?
[00:41:18.140]Okay, back here?
[00:41:21.307]I was just gonna see
[00:41:22.726]if you're able to remotely tell
[00:41:23.920]if someone has their fume hood in the emergency mode,
[00:41:26.460]which would be consuming--
[00:41:27.710]We can see that, but we as the Maintenance Department
[00:41:33.140]don't want to say "Why"; that's more of a situation
[00:41:37.070]for Environmental Health & Safety.
[00:41:39.540]But we are working with EH&S on identifying a report
[00:41:45.410]that will let them know if somebody's
[00:41:49.030]put these in emergency mode.
[00:41:52.070]Does proper use of a fume hood
[00:41:53.790]require the lab occupancy switch to be on?
[00:41:56.830]Good question.
[00:41:57.663]No, it does not.
[00:41:58.780]So the fume hood works independent of whether
[00:42:01.170]you've got an occupied room or not;
[00:42:04.540]it'll maintain its face velocity no matter what it's doing.
[00:42:11.620]Are there any other questions?
[00:42:13.010]Oh, great. How do we get
[00:42:14.490]one of those fume hood controls for an old fume hood?
[00:42:18.500]We can do that.
[00:42:20.100]You can certainly send a request
[00:42:21.750]for an estimate into Facilities.
[00:42:24.500]We can install air flow sensors and at least--
[00:42:27.400]We may not be able to put a valve on it,
[00:42:29.140]but we could at least put an air flow sensor in there
[00:42:31.710]and show you what's going on.
[00:42:39.850]Any other questions?

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