September 2013 – Geeky Girl Engineer

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.

First Time Blood Donor

Posted on September 4, 2013 by geek

Today I donated blood for the first time. Fifteen years ago doing that would be ridiculous because I had such an awful fear of needles. Then I got diagnosed with hypothyroidism, and I had to have my blood taken every six weeks for a year or so until we found the right thyroid medication level. I had to learn to deal with my needle phobia, which I learned today is trypanophobia. I also learned that it makes a huge difference who puts the needle in you. Medical doctors, with the exception of surgeons, are not allowed to touch me with a needle. Only nurses who insert needles on a regular basis may touch me with a needle. If I am having a needle inserted into a vein, I demand a phlebotomist. The other problem I have though is the needle sitting in my vein. It is not the pain. It is the idea of a needle just sitting in my vein that makes me nervous. I had extremely minor outpatient surgery about ten years ago. The nurse anesthetist who inserted my IV was wonderful. I barely felt it, but looking at the IV taped to my hand still made me nervous. Of course in that instance it did not help that the saline bags were kept refrigerated, and since I was dehydrated due to the dictated not drinking after midnight, I had ice cold saline gushing through that IV into my veins. That was the most horrible part of the entire procedure.

Anyway, there was a blood drive at my office today, so I decided to finally conquer my nerves and donate blood. Someone today asked me why I decided to become a donor. Is altruism to strong a word for something like this? Besides being incredibly nervous and a little bit of uncomfortableness, I potentially am saving someone’s life with no harm or risk to myself. So why not? I, or someone I love may, or probably will, need someone’s donated blood someday. Pay it forward, right? In fact someone on Twitter thanked me as a recipient of an anonymous blood donation last year. That made the experience that much better. I donated blood. I am still alive. I didn’t even faint or get woozy. I’m pretty proud of myself.

Partially to keep myself distracted, I live tweeted my blood donation. Here is the Storify of the event.

Caprese Soup

Posted on September 3, 2013 by geek

I love heirloom tomatoes. I mean seriously love them. During the summer, I stop at the farmers’ market almost every week to buy them. One of my favorite dishes to make with them is something I created that I call caprese soup. I named it that because it is fairly similar to caprese salad, but the main import difference is that I keep all the tomato juice. The most important ingredient is of course heirloom tomatoes. Overripe, incredibly juicy heirloom tomatoes are best, like the ones I got at the farmers’ market today.

heirloom tomatoes

The other ingredients are fresh mozzarella, fresh basil, extra virgin olive oil, and balsamic vinegar.

Here’s how I make it.

1. Take the heirloom tomatoes and chop them into bite size pieces. Keep as much of the juices as possible, and put the pieces and juice into a large bowl.

2. Cut the fresh mozzarella into smaller pieces and add to bowl. Add as much or as little mozzarella as you want.

3. Add the fresh basil torn into small pieces. Add the olive oil and the balsamic vinegar, in enough amounts that the tomatoes and mozzarella are coated well. I suggest adding more vinegar than oil.

4. Mix well making sure all the tomato juice, olive oil, and balsamic vinegar are well mixed.

5. Allow to marinate overnight in the refrigerator.

6. Enjoy. I suggest serving with french bread or some other bread that can be used to soak up all the juices to thoroughly enjoy.

It is one of my favorite summer meals, and look how gorgeous it is.

caprese soup

Losing 50 lbs

Posted on September 2, 2013 by geek

I write this post wondering if I will ever publish it. I don’t really like to talk about my weight as it has been a struggle for my entire adult life. However, it is impossible to hide that struggle when the weight loss or gain is on the order of 50 pounds. People who see me everyday and thus might not notice a gain or loss of ten pounds have started noticing my weight loss. I am not exactly trying to hide it, but I am just scared of whether or not I can keep it off. I’ve been here before.

This current weight loss journey started when I moved to the DC area. I’ve written about how I changed my life from one based on getting around in a car to a mainly pedestrian life. I did that mainly so that I wouldn’t have to deal with DC traffic, but truthfully I am not one of those people who loves their car, and I am just as happy walking. In adopting this pedestrian life, I lost about 25 pounds over the course of about nine months. I wasn’t trying to lose weight, and the only reason I knew I was was that every time I saw my physician, she happily exclaimed that I had lost more weight. The only thing I had changed in my life during this time, besides the pedestrian lifestyle, was to stop bringing home sweets. I have a problem with sweets, so I decided for Lent last year that I would eat sweets guilt free outside the house, but I just wouldn’t bring them home. [I’m Episcopalian, and I always try to give up something for Lent.] I knew from experience that if I tried to give up sweets entirely, I would just want them more, and I would doom myself for certain failure.

After my physician’s visit nine months after the first time I had seen her and the realization that I had lost a total of about 25 pounds, I realized some of my clothes had seemed slightly looser. Obviously the weight loss was nice, but I wasn’t entirely sure what I wanted to do. Sure, I wanted to keep doing what I was doing to either maintain that weight loss or perhaps slowly lose a bit more. For the past several decades I have made lifestyle changes that had aided that weight loss, but at this point in my life I had sworn off diets. There has been some research to show that yo-yo dieting is really not healthy, and I didn’t want to do it in any event. I have lost a significant amount of weight twice before. The first time I was in my 20’s and lost about 60 pounds on my own. I did it by a lot of exercise and what I now realize was rather unhealthy caloric restriction. The second time I lost about 40 pounds on Jenny Craig. I couldn’t get past 40 pounds even though I was following the diet fairly faithfully. The fact that I got diagnosed with hypothyroidism part of the way through my diet with them may have affected things. I also think that my calories may have been restricted too much. I exercised very often, and at least at the time, the prescribed Jenny Craig diet didn’t account for calories burned through activity. I know someone currently on Weight Watchers, and she said their plans now have you eat more food based on how much exercise you get. I have no idea if Jenny Craig now does this, but as I know from personal experience that I need to tailor my caloric intake based on my exercise or caloric output. Medical experts generally agree that losing more than a pound of so a week is not generally healthy, and if I were to restrict my calories to less than 1700 calories daily and exercise the way I do, in theory I would be losing at a rate that is not healthy.

So I was down 25 pounds without really trying, and I wasn’t sure what to do. I really loved the idea of losing more weight, but I hated the idea of losing more to only gain it back. Not too long after I started trying to decide if I wanted to try to lose more weight, I heard about Fitbit. I decided to get one and see just how active I was. I discovered that I was quite active compared to the average person, and with the Fitbit, I became even more active. I am a data geek, and I love collecting data on myself. It gave and still gives me encouragement to keep moving and be more active. About a month after getting the Fitbit, I purchased a scale to weigh myself and started using Fitbit’s system to keep track of what I was eating. By then, I had decided I would try to keep losing weight, but I was also not exactly going to diet. That is, I would try to limit my caloric intake by 500 calories a day (to lose a pound a week), but if I went over every once in while when out with friends or something, so be it. I had made enough lifestyle changes before that, once I started counting calories, I didn’t have to change that much anyway.

So now it’s 20 months since I first started losing weight, and nine months since I really started to try to lose weight. I weigh myself everyday, which while some say is not beneficial, I do because I’m a data geek. The more data the better, and I’ve become fascinated with the daily changes of up then down. I’ve also noticed that I tend to be stagnant in weight loss for a week or two, then drop three pounds overnight. While this definitely occurs with my hormonal cycle, it also appears to happen at unrelated times. From what I’ve found searching the internet, this is fairly common. One person has proposed that it is related to water replacing triglycerides in fat cells temporarily, but he readily admits, he has no proof of it. Whatever the reason, it seems to happen to me.

I exercise almost everyday, and I try to walk as much as possible. I log all my food to count the calories. I’m sure to some people this would be beyond tedious, but I feel like I am running an observational science study on myself. I still don’t exactly consider myself to be dieting. If I weren’t trying to lose weight, I might eat a bit more bread or something, but I also realize that if I have any chance of keeping this weight off forever, then how I live my life now is for the most part how I am going to have to live it forever. I will never be one of those people who can eat whatever they want and never exercise and not gain weight. I am fairly sure if I ever stop exercising on a regular basis, i.e. several times a week, I will gain weight. Also, when I say exercise, I am not talking a brisk walk a couple of times a week. I exercise on my elliptical machine for an hour several times a week. I started running several months ago, and I try to go for one or two 3 mile runs plus a long run, which at this time is 5 miles, each week. I do resistance training with free weights and resistance bands. I also walk everywhere and try to go for a walk at lunch every work day.

Now, I’ve lost over 50 pounds total. It’s 55 pounds according to the scale this morning, but I easily go up and down a couple of pounds each week. I suppose I should be happy and proud of myself. I am, but I am also terrified. As I said, I’ve lost lots of weight before. Losing weight, or at least the initial weight loss is easy. Keeping the weight off and losing more is incredibly hard. I am not sure how much more I need to lose. My guess is that I need to lose another 20 to 30 pounds. I’ve dropped three or four dress sizes. I haven’t bought that many new clothes though. The tops are just loose on me. However, I have had to buy some new pants because I can cinch them with a belt because otherwise they would just fall off me, but some I have to cinch so much they look clownish on me. Several people have asked why I don’t buy more new clothes. My answer is two-fold. I hope to lose more weight, and thus I don’t want to buy clothes that won’t fit me in several months. Two, but just as importantly, I am scared that I can’t keep the weight off. I have a huge stack of clothes in my closet that don’t fit me anymore. I can’t bring myself to donate them yet because I am just too scared of my ability to keep the weight off.

I suppose the good thing is that I realize this is not a diet. This has to be a lifestyle change to last my life. To a certain extent, I feel like an addict in recovery. My addiction is food, so I can’t go cold turkey (no pun intended). I have to eat. I just have to always eat smart, and I always have to get a lot of exercise. However, I like what I eat right now. I eat lots of fruits and vegetables. I eat lean meats. I never have been a fan of fried food or many other really fattening food. What I eat now I am entirely happy to eat for the rest of my life. This as opposed to when I was on Jenny Craig. I am not trying to slam Jenny Craig, but at some point, even if I had been completely successful with that diet, I would have had to transition to “real” food. I fix healthy meals and enjoy eating them. I don’t eat disgusting low calorie food just because it is low calorie. I eat healthy, nutritious, delicious food that I happen to make low calorie.

So if you know me personally, that is what is going on with me. That is why some of my clothes are falling off me. Perhaps now, you also understand why I am not screaming from the rooftop that I have lost over 50 pounds because it will just be all the more embarrassing if I gain it back. If you compliment me, know that I appreciate it. I really do. I just don’t have enough confidence in myself to fully be happy and proud of myself. I’ve been here before.