Getting Accurate Porometer Data Cleaning and Calibration Q&A
What am I supposed to be cleaning?
An aluminum tube runs from the leaf surface up through the head of the porometer's sensor clip called the diffusion path. That's the critical area, and the easiest way to get at it is to (carefully!) push out the pin on the sensor clip. Lay the pin and the bottom (sensor free) part of the clip aside. A Teflon screen covers one end of the tube. Pry it off (carefully!) with a sharp bladed knife.
How can I clean the path without harming the sensors?
Clean carefully! You can use distilled water, a little mild soap, and (if you're incredibly careful) a razor blade. Don't use solvents of any kind, including alcohol. They mess up calibration of the sensor head.
Why can't I use alcohol to swab it out?
The porometer is very sensitive. That's a good thing, but it means you have to exercise caution around solvents. The sensors on the prototype porometer were thrown out of calibration by fumes from the glue used to hold foam in the original packing case. Calibration can even be messed up by storing the sensor close to a gasoline can. You definitely don't want to attack the sensor head directly with alcohol or (heaven forbid) acetone.
Won't water mess up my relative humidity measurements?
Yes, it will. You need to open up the head and let it dry out for 24 hours after cleaning. Cleaning and drying are easier if you carefully push out the pin that holds the clip together.
The Teflon screen is very dirty. Can I clean it?
No, don't attempt this. Just pop in a replacement screen. You got five with your porometer, and if you've run out, call Decagon (1-800-755-2751) for replacements.
Anything else I should do while I have the Porometer apart?
Sure. This is a great time to inspect the rubber seals that seal the clip to the leaf when you make readings. If the seals are worn, you can peel them off and replace them with the extra seals that came with your porometer. If you can't find spares, call Decagon at 1- 800-755-2751 to request more.
All this talk about knocking the porometer out of calibration is making me nervous. Do I ever need to recalibrate?
In spite of its sensitivity to solvents, the porometer is pretty stable under normal conditions. It doesn't need daily or weekly calibrations. We do recommend that you send your porometer head in for recalibration once a year. We'll clean it out, check and recalibrate it, and even restock your case with replacement Teflon disks and seals.
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