Testing, Testing…

…1-2-3 testing… (Is this on?) An important part of our preparation is to test all of our equipment once we have it here in McMurdo. Just like the sound checks at a big concert, we want to make sure everything is working before the big show! The biggest piece of equipment we use is our metabolic chamber. It is 8 feet long, 3 feet wide, and 4 feet tall! It’s actually a modified Pelican case, which makes it airtight (and waterproof) everywhere except for where we added fittings for air flow. Before we left for our first season, I acted as the “test seal” and sat in the chamber for a couple of hours while my team tested the gas analyzers. This allowed me to get a seal’s-eye view of what it’s like inside the chamber. Even though we pull air at 500 L/min through the chamber, I could not feel the air flow. There’s also a lot of natural light that gets into the chamber through the windows and even through the walls. It was actually pretty cozy in there; however, I did notice that the metal latches on the outside of the chamber make very loud, echoing noises on the inside. Now that we know that, we make sure to handle the latches as gently and as quietly as possible so we don’t bother the seals with those noises. We want our pups to feel and be as safe and as comfortable as possible.

So what does this giant chamber do? The chamber measures the oxygen consumption of the seals – how much oxygen they take out of the air. This tells us how much energy they are using. For everything to work properly, we need to make sure there are no leaks anywhere. We do this by sending some pure nitrogen gas into the empty chamber at a known rate, and seeing how much of the oxygen is displaced by the nitrogen. If there are no leaks, we can calculate exactly how much the oxygen levels should change. When we ran our first calibration test for this season, we found that the oxygen was not changing very much at all. This told us that there was a leak somewhere. So then we had to find the leak… We checked the sides of the chamber, where the lid attaches, and did not feel any leaks. We also checked the hoses and connectors, and they seemed fine. Then we checked the housing for our air filter and noticed it had gotten bent during the time it was stored here since last season. This was the source of our leak…or so we thought.

Although an amazing machinist here on station was able to make our filter housing look and work like new, the next calibration gave us the same results. We have spent the last week troubleshooting every part of our setup, and we have narrowed it down to our Flowkit, the machine that pulls the air through the chamber at a constant 500 L/min. We discovered that one of the internal electronic components was loose and it ended up coming off. This just goes to show that, even though calibrations can seem boring, it is so very important that we take the time to check everything before we go out into the field with all our equipment. Pretty soon, it will be show time!

Written by: Heather Liwanag