Engineering – Page 10 – Geeky Girl Engineer

Let’s Talk Stats, WMATA

Posted on December 4, 2013 by geek

The Washington Metropolitan Area Transit Authority (WMATA) has problems. Lots and lots of problems. They’ve had an ad campaign called “Metro Forward” for a while now trying to let people know how they are using the money that customers pay to improve the system and do much needed upgrades and renovations. The customers, including myself, want a reliable safe system, not a PR campaign though. Recently they have unveiled a few new ads that in most people’s opinions are sexist, stupid, and somewhat confusing. The ads consist of posters with either two men or two women talking. A few examples that I have been able to find:

Woman 1: “A Metrobus travels 8,260 miles between breakdowns. Didn’t know that, did you?” Woman 2: “Can we just talk about shoes?”

Man 1: “A Metrobus travels 8,260 miles between breakdowns. Didn’t know that, did you?” Man 2: “Can we just talk about sports?”

Man 1: “When we take Metrobus, do you think we’ll get to ride the new 32-foot Orion model, or the latest Xcelsior model?” Man 2: “Dude, it’s a bus.”

Woman 1: “I love the way the tamping process aligns and elevates the rails for Metro, don’t you?” Woman 2: “I have no idea what you just said.”

Man 1: “So Bobby, did you catch all those new rail fasteners on Metro today?” Man 2: “No Billy, not so much.”

So WMATA, I’d like to speak to you as a woman and as an engineer. First, the last two ads that I have listed, about the tamping process and rail fasteners, I don’t even understand these. I have a vague understanding what these mean, and if I bothered to spend time on the internet researching, I have no doubt I would understand it better. However the average customer is not going to know what this means, and quite frankly, nor should they be expected to know. Furthermore, these posters seem to insinuate that there is something wrong with them because they don’t know. If things work properly in engineering and technology, people never know how things work, and there is nothing wrong with that. It is only when people’s ignorance of how things work can mess up a system, that engineers really care that they are ignorant. [Example, people who pour grease down the drain and not understanding the problems in the wastewater pipes to which this can lead.]

As for the ad where Man 1 asks which type of bus they will be on, Man 1 is clearly a bus geek, and Man 2 clearly is not. I respect Man 1’s geekitude, even though I don’t share it about buses. Man 2 does not respect the geekitude. How are they friends?

Now, let’s address the ad that is causing the most trouble for you WMATA. The one about the average bus breakdown rate. Most women think this is sexist because Woman 2 just wants to talk about shoes. So let me be clear, it IS a sexist ad. However, in your defense, the male version makes Man 2 look shallow also, so I guess that’s a win-win at making both sexes look stupid. I mean I like shoes. Most women like shoes. I like sports, not as much as many men and women, but I can have a conversation about it. Here’s the thing though. Shoes are not my sole interest. I am I nerd, and I would love to talk about the breakdown rate of your buses. That’s what you say you want, to get people to talk about the system’s reliability. So let’s talk about it.

You claim that “a Metrobus travels 8,260 miles between breakdowns.” Is that the mean or the median? What is the standard deviation? Can you give me a plot of the data? Are the data normally distributed? What is the skewness and kurtosis of the data? I would be willing to bet that your bus breakdown data has some really nice skewness. I bet your new buses work rather nicely, and your old buses don’t. Hence, your new buses probably can go much longer than 8,260 miles between breakdowns, but your old buses probably can go much less. Is one or the other skewing the mean and by how much? How does this lovely statistic that you are presenting to us compare with other DC area buses like those of ART, CUE, DASH, etc.? How does it compare with the breakdown statistics of other large metropolitan bus systems like New York, Los Angeles, Chicago, Houston, etc.? You are presenting a statistic in a vacuum, and it is almost meaningless.

To get past that breakdown statistic, what are your on-time statistics, you know those statistics your customers actually care about? Most WMATA riders really don’t care what kind of bus they are on. They just want a bus runs on time, and actually picks them up at their bus stop, instead of leaving them because either the bus is too full or for reasons the customer never finds out, the bus just doesn’t show or stop. [Yes, this has happened to me several times.]

Speaking as a customer, I don’t want a PR campaign at all. I most definitely don’t want a PR campaign that makes my fellow riders look like fools. I want a system that works. I want a transit authority that actually responds to customer complaints. I want a transit authority that does more than send a automatic form response when I submit a complaint about a driver running a red light. I want to know that things will actually change and improve, and right now WMATA, you just keep failing at that, and this PR campaign does nothing to improve things. In fact, it makes things worse.

Old NY City Hall Subway Station

Posted on November 17, 2013 by geek

Entrance from platform to mezzanine level

Saturday, I got to tour the abandoned New York City Hall subway station. The New York Transit Museum gives tours of it a few times a year, and this tour is completely worth the membership in the museum. The old City Hall subway station was originally the southern terminal of the original Interborough Rapid Transit (IRT) subway route. The station is located on a single 600-foot long track loop that is located south of the current City Hall/Brooklyn Bridge subway station. The track loop is still used by the #6 subway line. After a #6 train drops off passengers at the City Hall/Brooklyn Bridge station from a southbound route, it then uses the loop to return to that station as a northbound train. For our tour, we met at the southern end of the City Hall/Brooklyn Bridge subway station, and then once all passengers had been offloaded from a southbound #6 train, we got on for the short trip to the old City Hall station.

The old City Hall station has a platform that is 400-feet long and is completely curved. This short and completely curved platform is part of the reason why the station is no longer used. The ten-car trains now used don’t fit in the station, and it is a serious hazard stepping off the train to that platform. [Our MTA guides used a short wooden platform to allow us to easily and safely get off the train onto the platform.] The station was closed in 1945 because passengers preferred the Brooklyn Bridge station due to its longer and straight platform and also because both local and express trains stopped there.

The station is completely gorgeous. There is a mezzanine level where passengers would buy tickets. The mezzanine is square with four arches that form each of the walls, and an arched ceiling joins the four arched walls. At the center of the mezzanine ceiling is a glass skylight. One of the arches of the mezzanine forms a passageway that leads down to the platform. The platform is then made of 15 more arches. Three of the arches have three glass skylights each. Electric chandeliers hang from each of the arches to provide light. All of the arches are created by Guastavino tile arches. The walls and ceilings are covered in green, brown, and cream tile. Interestingly, much of the cream tile is unglazed and rigged. Evidently this tile was never supposed to be exposed, it was rigged and unglazed because it was supposed to be covered with cement, and the ridges would provide more surface are for the cement to stick, in the same way as when tiling, the ridged side of a trowel is used to create ridges in the cement before placing the tile. However once the tile was placed, the station architects liked how the exposed ridged tile looked.

On stairs from platform looking up to mezzanine

Mezzanine ceiling

Mezzanine skylight

Mezzanine skylight glass

Stairs from mezzanine to surface. Doors now close off the exit.

Tiles on the mezzanine walls

Arch of passageway to surface. The Guastavino tile arch system can be seen easily.

Close up of tile on arched passageway from mezzanine to platform

Tile on mezzanine wall. Ridges on unglazed white tile can be seen.

Skylight above the arch that leads from the platform to the mezzanine

The middle arch on the platform where the passageway from the mezzanine ends. The arch has three skylights. Opposite the passageway are three plaques commemorating those who helped in the station’s creation.

The platform. It is completely curved.

The end of the platform.

Chandeliers hang from each platform arch

The skylights in one of the platform’s arches.

One of the platform’s skylights. The glass has fallen out of one of them, and the glass in the street level concrete can be seen.

A #6 train passing through the station. A huge gap exists between the train and platform edge.

One thing I have always appreciated about the New York subway system is the tile work. All the stations have tile work, and generally each station has a somewhat unique tile work for at least the station signs. Some stations have really unique and beautiful tile work for example the Times Square and American Museum of Natural History stations. The tiles themselves in the old City Hall station are not gorgeous, but the way they are placed together in the arches are. Therefore for final comparison, below are the station signs at the old City Hall station and the new City Hall/Brooklyn Bridge station.

Old City Hall station sign

Modern City Hall/Brooklyn Bridge station sign

Delancey Williamsburg Bridge Rail Terminal

Posted on November 14, 2013 by geek

I joined the New York Transit Museum this year so that I could go on some of their members only tours of some real cool transit places. Today I toured one of those places, the old Essex/Delancey trolley terminal from the Williamsburg Bridge. Trolleys from Brooklyn came across the Williamsburg Bridge to Manhattan and then turned around in this terminal. Trolleys in Brooklyn were evidently on a different rail system type and thus couldn’t continue onto the Manhattan rails. I won’t try to give the history, as so many places can be found, which do it much better, such as this one. The terminal is right next to the Delancey and Essex subway stations and can be seen from part of the platform. Inside the terminal area, some of the old tracks, paver stones, and rails can be seen. While I found those interesting, I also just loved being able to walk in a behind-the-scenes area that the general public usually can’t access.

Another thing I found interesting was the condition of the columns and beams. Like almost all parts of the New York underground, the area is continual being eroded by water that seeps in from groundwater and storm water that flows through various cracks in the utility areas. Thus much of the metal support structures were badly rusted. Some parts of the area have been rehabbed but not all. It was a stark reminder of how continual maintenance is needed on essentially everything humans build. If you are not an engineer, you can be forgiven for not understanding that once something is built, it still needs maintenance. It can’t just simply be left to itself to continually function properly for all eternity. Unfortunately most politicians, who hold the purse strings to maintenance funding, don’t seem to understand this.

There is an idea or plan by some to turn the area into an underground park called the Lowline. It would be incredibly interesting to see that if it happens. In the meantime, I’m glad I got a look at this piece of New York’s transportation history.

View of Delancey Terminal from subway platform

View of subway platform from the Delancey Terminal

Subway train passing by Delancey terminal

Wide view of Delancey terminal with old track monitoring office in background

Wide view of Delancey terminal, old tracks can be seen in foreground

Wide view of Delancey terminal parts of which are wet from normal seepage

Old track in paver stones terminating at a more modern tiled wall

Old track in paver stones

Old tracks

Old rail, which is held inside a wooden casing. Wood was used since it doesn’t conduct electricity, and rail was electrified.

Rusted column

Rusted beams and columns

Rusted beam

Stalactites from water seepage near rusted metal

Rusted and rehabbed beams

Washington Monument in Scaffolding

Posted on November 3, 2013 by geek

The Washington Monument is currently covered with scaffolding while it is repaired for damage from the 2011 earthquake. Perhaps I am biased because I am an engineer, but I think the scaffolding surrounding it is both an engineering feat and a work of art. It is also amazing to view. In one of the photos below, you can see how they actually have suspended scaffolding within the supported scaffolding, which I think is totally cool. They have been lighting it up at night, but tonight is the last night it will be lit. They are almost done with the repairs, and the lights need to be removed to finish repairs. I finally got out today to photograph the Washington Monument with the scaffolding. Personally while I will be happy when they finish repairs, I also think it is beautiful now.

Reflection on the Potomac River

Reflection on Lincoln Memorial Reflecting Pool

In scaffolding

Washington Monument under repair with construction cranes

Scaffolding

Suspended scaffolding within the supported scaffolding

Scaffolding

At sunset

Scaffolding Lighting

Reflection on Lincoln Memorial Reflecting Pool

#StandingwithDNLee

Posted on October 12, 2013 by geek

I’m privileged. I know I am. I have been my whole life. I’m a white woman who grew up in middle class suburbia. I went to good public schools through high school, and I went to very good public colleges and universities for my Bachelor’s, Master’s, and Doctorate. I grew up in the South, which I know many associate with racism, but I went to school with plenty of minorities. My one and only “disadvantage” is that I am female, in particular a female engineer and scientist. I do not consider being female a disadvantage, but females tend to get discriminated against as if we are less then males somehow.

This morning much of my Twitter timeline was filled with fellow scientists and then many other people getting very mad at Scientific American over its treatment of one of its bloggers, Dr. Danielle N. Lee. I encourage anyone who reads this post first to go read Isis the Scientist’s blog post about what happened to Dr. Lee, which includes Dr. Lee’s original post. The original post was on Scientific American but now is no longer there, which you can read about in Isis the Scientist’s follow up post. The extremely short version of all this is that an editor a scientific blogging website asked Dr. Lee to write some articles for free and Dr. Lee said no, the editor called her a whore. [Seriously, go read Isis’s blog posts.] My first thought upon reading about all this was, so you think calling a woman a whore is the way to persuade her to do what you want? Really? Does that work for you normally?

Somewhere is the incredulous, anger, and sympathy and respect for Dr. Lee upon learning all the details of these events, I thought how lucky I am. I spent the better part of my childhood in Texas, which has more than its share of racist, sexist pigs, yet I can’t actually remember a time I truly had to deal with one on a personal basis. Last year, I wrote about how lonely it can be to be a female engineer, both in school and in the workplace. I’ve been surrounded by men in the classroom and workplace, since pretty much my freshman year of college. Truthfully though, with one glaring exception, all the men I’ve studied or worked with have for the most part treated me as an equal. Maybe they didn’t, and I was just too oblivious to notice.

The one glaring exception was at the company where I had my first full time job after finishing my Bachelor’s and Master’s degrees. My manager, a senior engineer, would occasionally make some remarks that made 26-year-old me rather uncomfortable, but I didn’t think were truly sexual harassment, and it has been so long ago, I don’t even remember what they were. Then shortly before my birthday, the other female engineer in the office and the female secretary happen to be in the copy room with him when upon the female engineer exclaiming “oh, it’s [GGE]’s birthday next week,” he said, “does that mean we get to spank her?” I was not in the room at the time, but this was a tiny office of about nine people. There are no secrets in an office that small, and I was good friends with the secretary. I heard about this comment pretty quick. To say this comment made me uncomfortable would be putting it mildly. I went to one of the other senior engineers, who happen to have previously been my manager, and I told him what was going on. I told him I didn’t want to make a big deal out of any of it, but I really wanted the comments to stop both for my and every other female’s sake. He assured me he understand, thanked me for coming to him, and promised to take care of it. Within a week or so, a human resources person from the company’s corporate office was in the office, and everyone was taking mandatory sexual harassment training. My former manager had my back. He took care of it, or really he made sure the company took care of it. Whether this engineering company that was definitely dominated by men took care of it because they seriously won’t take this kind of behavior, or if they were more motivated by fear of a sexual harassment lawsuit, I don’t know. What mattered was, they took me seriously, and they reacted exactly the way they should have.

So to return to Dr. Lee, I was thinking how lucky I have been to only have had one bad experience in my personal and professional life. Scientific American seems to not have her back, and the one time I had a problem, my company had my back. Then I stopped to think, why am I lucky to have only had to deal with one sexist idiot in my career? Why should a woman have to be lucky to not be called a whore? Why should I consider myself lucky for be treated like an equal in school and work? Why should I consider myself lucky for people respecting the career decisions I have made and for whom I would and wouldn’t work? Perhaps that is why I am a feminist because I am confident in the notion that I AM AN EQUAL. I have respect for myself. Calling me names will not induce me to do what you want. I will respect you if you respect me. Isn’t that what we learned in Kindergarten? Treat others the way you want to be treated? As for Scientific American, I cannot understand why they took down her post. I cannot understand why they are not supporting her. Their explanation makes no sense, especially to a regular reader of their blogs. They failed Dr. Lee, and they failed their readers by not supporting her. Their silence on her being called a very ugly name is deafening. People and companies who do not stand up against racism and sexism only allow it to continue. Until Scientific American apologizes publicly to Dr. Lee, I will be boycotting them. I am sure not going to go anywhere near the blog website whose editor called Dr. Lee a whore. I wish I could do more. I wish racism and sexism would end, but until they do, I intend to stand up for myself and anyone else who face them.

Book Review: “Conquering Gotham”

Posted on October 10, 2013 by geek

This isn’t really a proper book review but really more of a book recommendation. I’m not a writer or literary critic. I’m just an engineer who just finished reading a book about the history of one the greatest engineering feats in the early twentieth century and want others to know how interesting a book it is. The book is “Conquering Gotham: A gilded age epic: The construction of Penn Station and its tunnels” by Jill Jonnes (Penguin Group, 2007).

The book chronicles some of the history of various people and companies who tried to link Manhattan Island and New Jersey via bridge or tunnel. When the book starts, the Brooklyn Bridge, which was an engineering feat in itself, has been built, but the only railroad connection to Manhattan Island was via New York Central and its bridge over the Harlem River. Thousands of commuters, other people, and cargo must use ferries across the Hudson River everyday to get to Manhattan from New Jersey. Dewitt Clinton Haskin unsuccessfully attempts to build a tunnel underneath the Hudson River, but due to construction and financial problems, the tunnel was abandoned. [Decades later the tunnel would be completed and in present day is used for PATH trains.] Gustav Lindenthal unsuccessfully tried for decades to build a bridge across the Hudson River but was never successful due to an inability to get funding. Pennsylvania Railroad (PRR) under the leadership Alexander Cassatt is determined to get their trains into Manhattan in some manner instead of having their tracks end in New Jersey and their passengers needing to take ferries across the river.

The book describes how PRR explores the possible ways to get their trains to Manhattan Island and finally settles on an audacious plan to build two tunnels underneath the Hudson River, two tunnels under and through Manhattan, a grand station in a not so nice section of Manhattan, and four tunnels underneath the East River to further expand their tracks into New England. Completing this audacious plan is fraught with many engineering and financial difficulties and is further complicated by the need to deal with the corrupt New York City Tammany Hall politicians, which put about as many delays on the project as the difficult engineering. The history is fascinating, and Jonnes describes it really well. The book is not a dry history textbook. She describes the engineering obstacles in a way in which a non-technical person will understand and be interested, although as an engineer, I actually would have liked more details about some of the engineering issues, particularly with the tunnels.

The final chapter describes some of the post-completion problems, including the eventual decline of the railroads due to automobiles and then aviation. The modifications made to Penn Station after its completion and finally its destruction and replacement with the atrocious Madison Square Garden are also discussed. I have traveled on Amtrak trains many times via the Hudson River tunnels and twice via the East River tunnels. I have a much better appreciation for the difficulties in their construction now. I am also now even more sad to have never seen Penn Station in its original glory. In my humble opinion, the current Penn Station with Madison Square Garden is the ugliest and most ill-designed train station ever, and New York City deserves so much better. Of course, New York City is partially to blame for the destruction of the original and the construction of the current Penn Station.

If you are at all interested in history, transportation, or engineering, I highly encourage you to read this book. It is a great read. [I received no compensation for this recommendation, and I checked this book out from my local library.]

Household Hazardous Waste Disposal

Posted on October 3, 2013 by geek

Previously I wrote, or ranted, about stupid smoke detector design, and at the end of the post I mentioned that smoke detectors have a small amount of radioactive material in them, and thus they should be disposed of properly. I didn’t say specifically how because it really depends on where you live. I live in Virginia, and I have since learned that there is no place in Virginia to dispose of them. My county’s website says they have no way to dispose of them and to try to return them to the manufacturer, but if you can’t find any other way to dispose of them, they can be thrown away in the trash. I contacted Kidde, the manufacturer, and they said they will accept them, you just have to mail the smoke detectors to them. The customer service representative I spoke to said just put “for disposal” on the package, and they will take care of them. I actually had a total of three to return because I had the malfunctioning one plus two ones I had originally bought before I had the hardwired ones installed. So last month, I mailed three smoke detectors back to Kidde. It cost me $6.15, but I now have a clear conscience. This may seem a bit much to some people, but I am an environmental engineer. My career has mostly been dedicated to cleaning up and properly taking care of human and hazardous waste. It has also been about dealing with contamination when waste was not taken care of properly, so there is no way I am going to improperly dispose of waste unless it is completely impossible not to do so.

Here is a fun quirk of United States environmental law, my smoke detectors are non-hazardous because they were used in my house. Those same smoke detectors, if used in a commercial or other non-household setting, are hazardous. Hazardous waste in the US is regulated through the Resource Conservation and Recovery Act (RCRA, pronounced rick-ra). Under 40 CFR §261.4(b)(1), “household waste, including household waste that has been collected, transported, stored, treated, disposed, recovered (e.g., refuse-derived fuel) or reused” is considered to be non-hazardous and exempt from RCRA regulation. There are a bunch of reasons why this exemption is in RCRA, but how you treat your legally-not-hazardous, but technically-hazardous, household waste comes down to a bit of just because you can do something, doesn’t mean you should. However, disposal of household waste is also governed by state and local regulations. Just because federal laws allows you to dispose of household hazardous waste in the trash, does not mean your municipality will because they are the ones who actually have to deal with the waste.

Most people know that fluorescent bulbs contain a small amount of mercury, and thus if you ever break one indoors, you should open the windows and leave the room while the mercury volatilizes. It is because of this mercury that most (or possibly all) municipalities and/or waste disposal companies state that fluorescent bulbs should not be put in the trash. The vast majority of trash in the US is sent to landfills and the rest to incinerators, and mercury does not belong in either of these type of disposal facilities. Also, and just as importantly, the bulbs can easily be broken during transfer from your trash can to the truck, while in the truck (especially if it compacts), at the transfer station, at the disposal site, and all the places in between. If it breaks, the workers can be exposed to the mercury, and thus it is not just about protecting the environment but also the workers.

There is more household waste that is technically hazardous. Aerosol cans can become explosive if punctured. Various cleaning, home maintenance, and vehicle fluids routinely used in household are hazardous to the environment. Conversely, both prescription and over-the-counter (and for that matter illicit) unused drugs should be disposed of in a seal container and put in the trash. Putting unused drugs in the trash is far better for the environment than putting them down the drain where they will eventually get into the waterways. Wastewater plants are not designed to remove chemicals like drugs, but that is a post for another day. [I suppose if someone is trying to dispose of their illicit drugs it is most likely because the police are raiding their house, and they are really not thinking about the environment but about jail, but I still don’t want to drink water with trace amounts of cocaine because some druggie upstream of my water treatment plant was trying to evade arrest.]

The point of all this is, think before you toss something in the trash. Spend a little time on your municipalities website, as most now have them, educating yourself on what can and can’t be thrown in the trash and where things that can’t be thrown in the trash can be disposed. While you are at it, educate yourself on what things can and can’t be recycled in your area. There may be a recycling market in your area for something you didn’t even realize.

Inside a Water Filter

Posted on September 8, 2013 by geek

This is what happens when an engineer with an insatiable curiosity, power tools, and clearly too much time on her hands changes the water filter inside her refrigerator. Yes, that is pretty much it. There really is no other point to this post. Most normal people would take the old water filter and throw it away. I am not a normal person, and I wanted to see inside it, so I cut it open. Warning and reassurance to my mom: I wore a half-face respirator with PM10/VOC filters, goggles, and a leather glove while I cut through the filter. I strongly recommend if anyone else tries this, you do this also. I didn’t want to breathe in the dust or get it in my eyes.

Here is the filter before I began.

Photo 1: Used water filter for my refrigerator, side view

Photo 2: Used water filter for my refrigerator, top view

Here is the cross section after I cut through it length wise.

Photo 3: Water filter after length wise cut

The filter consists of a plastic shell that contains a hollow, round-bottom, cylindrical carbon filter. It is kind of hard to see, but the middle of the carbon filter is hollow. The carbon filter is held in the center of the plastic shell, so that there is free space all around the filter. Here are the two halves of the carbon filter side by side with inside of one shown on the left, and the outside of the other shown on the right.

Photo 4: Two halves of the carbon filter, showing inside and outside

As you can see the inside is still very black while the outside has started to gray. I have a hypothesis for the reason, which I will get to soon.

Here is the plastic shell with the carbon filter removed.

Photo 5: Plastic shell of the filter

Now here is a close up of the inside top of the plastic shell.

Photo 6: Close up of the inside of the top of the plastic shell of the filter

Notice how there are channels formed radiating from the center? The filter only has one opening, the hole in the center in the top, as is shown in the second photograph. Thus, one of the reasons I cut the filter apart was to try to figure out how it works. Water goes in through the center, but how does it get out? What follows is my engineering guess as to how it works. I am fairly sure the water comes in through the center hole, and the water pressure in the house forces it into the hollow center of the carbon filter and then through the carbon in all directions radiating outward. The water then is stored on the outside of the carbon filter until it is pulled by the refrigerator’s water dispenser or the ice maker. I think the white matter that has formed on the outside of the carbon filter that gives it a grayish appearance is calcium and magnesium, otherwise known as hardness. I live in Arlington County, Virginia, and our latest water report lists our water’s hardness as 125 mg/l. According to the United States Geological Survey, that puts our water as just in the hard range.

So if the water is stored on the outside of the carbon filter, how does it leave the filter to get to the water dispenser or ice maker? That is where I think those channels at the top of the plastic shell come in. In Photo 3, you can see the plastic top of the carbon filter fits flush with the top of the plastic shell, but the top of the plastic shell has those channels. Because of the space between the plastic shell and the carbon filter, the water can enter the channels from the outside then flow through the channels back to the hole in the center. However, the now filtered water does not flow back the same hole where the unfiltered water enters.The plastic tube at the top of the carbon filter prevents the filtered water from going back into the filter. Instead the filtered water leaves next to the center hole. In Photo 2, two rectangles can be seen next to the center hole, at approximately 1 and 6 o’clock in the photo. Those rectangles are holes, and it appears that the water that flows through the channels then can exit the filter through those rectangular openings. I can’t tell exactly this happens even though I examined where the filter attaches in the refrigerator. I did consider that perhaps I have the flow direction completely opposite, that is that the water enters through the rectangles, flows through the channels into the open space, then is forced through the carbon filter into the center of the filter. There are a variety of reasons, geometry, fluid dynamics, water pressure, etc., why I am fairly sure this is not the case.

So that is how my refrigerator’s water filter works. See this was educational. It was not just about me having fun with my Dremel rotary power tool and destroying something. Really it wasn’t.

Smoke Detector Stupidness

Posted on August 24, 2013 by geek

Last night at 3 a.m. my smoke detectors went off. There really is nothing like being awakened from a dead sleep to that extremely high pitched chirp and a female voice saying “fire, fire.” I, of course, immediately got out of bed and went in search of this supposed fire. There was none to be found. However my smoke detectors assured me there was. I then had to go through the house and pull all five of them from their wiring and in some cases pull out the batteries because pushing the button would not hush them. At 3 a.m., that was so much fun.

When I bought this house it did not have any smoke detectors. It had two wall mounted holders for smoke detectors, one in each the downstairs and upstairs hall. There were none in the bedrooms, and there was no wiring for interconnected ones. I decided early on that as I renovated the house, I would install interconnected wired smoke detectors and bring the house up to current code, even though it was not required. I’m an engineer that way. During Phase 2 of renovations, because the ceiling downstairs had to be opened to install a structural beam, the house lost grandfather status, and interconnected wired smoke detectors now became required by the County. No problem. I was already planning to do it. When it came time to install them, I decided to get combination smoke and carbon monoxide detectors. I had to buy all new ones anyway, so I might as well go for full protection.

This leads me to last night and my need to rant. My detectors are Kiddie brand. I mention the brand because there is an oligopoly of sorts on household fire alert and response equipment. All of them seem to work the same and have the same flaws. Modern houses generally will have interconnected smoke detectors so that if one detects smoke, all the detectors will go into alarm. There should also be one detector in each bedroom and in each hall. Interconnected fire detectors and their location are not universally adopted building code requirements for new construction but are a good idea. If you have a large house, it is possible for one to go in alarm and not awaken a sleeping person in another part of the house. Research has also shown that children do not necessarily wake to a smoke detector at all, in particular the tone. This is partially the reason why voice alarms have been added, but with children, personalized voice alarms with the parent’s voice may be needed to insure children are awakened.

If my detectors detect fire, they set off one set of chirps and say “fire, fire.” If they detect carbon monoxide, they set off another set of chirps and say “carbon monoxide.” If the battery is low, another chirp and “low battery.” Then there is some complicated series of chirp sequences to denote if it was previously in alarm, has malfunctioned, needs replacement, etc. that NO ONE COULD POSSIBLY DISTINGUISH THE MEANING OF AT 3 A.M. Mine were definitely yelling fire last night. As I ran around with a stool trying to figure out what the problem was, the hush button was not working at all. At one point, one of them said carbon monoxide, but I have no idea which one because they are all blaring at me at 3 a.m. The units also have some complicated series of LED blinks to denote in which mode (or possibly mood) it is. This is great, but they are IMPOSSIBLE TO UNDERSTAND AT 3 A.M. Also, as far as I could tell or at least understand, there was no way to figure out which specific detector set off the alarm and thus which one was malfunctioning. Maybe the LED is supposed to tell me this, but I couldn’t figure it out when all I wanted to do is stop the awful noise being blared at me.

Thus if any person who happens to work in smoke detector design happens to read this, these things are too complicated to understand when there is some malfunction or inaccurate alarm. I appreciate the voice that says fire, carbon monoxide, or low battery tells you what the supposed problem is. That makes it much easier to understand than which series of chirps are being blared. However, if you are trying to track down a malfunction, it is impossible. Stopping the blare seems to be impossible short of removing all sources of power. For interconnected detectors, I want and need to known which one started the alarm. I can’t figure out the problem if I don’t know that, ESPECIALLY WHEN IT IS 3 A.M. WHICH IS EVIDENTLY THE ONLY TIME DETECTORS HAVE A FLASE ALARM OR LOW BATTERY.

That ends my rant. While I’m on the subject of fire detectors though, please remember to change the battery every six months. Also, please remember when the detector itself needs to be replaced, never throw it in the trash. Smoke detectors contain a small amount of a radioactive substance. They are perfectly fine to have in your house, but they should not be disposed of in a landfill. Find an appropriate place to dispose of them. [Update: Please see my post Household Hazardous Waste Disposal on how I eventually disposed of my malfunctioning smoke detector.]

Mulching Plant Tour

Posted on August 17, 2013 by geek

About a month ago, I got a chance to tour a recycling plant. This Arlington County municipal recycling plant focuses on recycling yard waste. In the spring, Arlington County has curbside collection of yard waste in paper bags including invasive vines, leaves, dead plants, pine cones, etc. In the fall, Arlington County picks up leaves in paper bags from residents and also from curbside vacuum collection. All year long, Arlington County also picks up brush curbside. All of these waste streams are treated separately at the plant, and the plant also handles dirt and rock excavated during utility work.

The plant manager said he likes to think of the plant as a reutilization plant because something goes in, they process it, and then something goes out. Their operation is really quite impressive, especially when its 2.7 acres total yard size is considered. It is mainly this plant size that limits their ability to accept more waste for processing. Their biggest issue is dirt from pipe breaks etc. that is processed here. They reuse the processed dirt and rock for backfill, but if they can’t find a use for it, they have to dispose of it in a landfill.

The yard waste has to get to 140°F to kill any invasive weeds. Because the plant is located near a residential area, they do not accept food waste because of the odor it produces. They use lime on the yard waste solely for odor control. [Lime the inorganic material, which generally means calcium oxide (CaO) with some calcium hydroxide (Ca(OH)₂) not lime the fruit.] With the leaf waste, they achieve a 66% volume reduction to the leaf mulch product. Leaf bag collection mulch is mixed with dirt for final product.

Tub grinder that processes leaf, brush, wood, and spring yard waste

Dirt processing machine that sorts material by size

Stone crusher machine

Material going into trommel screen for separation. The trommel screen sorts dirt and big aggregate.

Material coming out of trommel screen after separation

As is often the case, fixing a piece of equipment involves a guy standing on the bucket of a front loader using a pole to move things.

Rock and concrete after separation

Dirt for separation by size

Leaf mulch product

Wood mulch product

Yard waste mulch product

The plant uses the product dirt to create this vegetable garden. It had wonderful looking vegetables, and in the past, they have entered the vegetables in the county fair.