Gevonden op de site van Oregon
http://www2.oregonscientific.com/servic ... ?t=1&cid=2
Een (Zeker voor Oregon Scientific-begrippen);) heel uitgebreide handleiding voor het kalibreren van ondermeer de PCR800 regenmeter. Nu eens even een goed moment zoeken voor het uitvoeren van "de grote regenmetertest"
My rain gauge does not tip equally or measure properly. How can I calibrate the rain gauge to resolve any inconsistencies or inaccuracies?
The buckets, or trough, can be calibrated by adjusting the screws located directly below the trough. To access the calibration screws, you will need to remove the outer cover on the rain gauge. To do this, remove the screws on the lower portion of the cover and pull the cover off. Once this cover is removed, you will see the trough, and two white, plastic screws below the trough. The balance of the trough can be adjusted by raising and lowering these screws. When testing for even tipping of the trough, count the number of drops that is needed on each side of the trough before it tips. Once an even number is required on each side, the unit will be calibrated. Even with equal bucket/trough tipping, tipping that occurs too soon or too late will lead to inaccurate measurements. To correct this, you must calibrate the gauge height. The area of the collection funnel is 78.54 square centimeters, which means that 1cm of rainfall equals 78.54 cc of collected water. Since each tip of the bucket is equal to 1mm of rainfall, each bucketful should be 7.854 cc. Here are some conversions to help: 7.854cc (ml) = 1mm rain = .04in rain 250ml = 31.83mm rain = 1.25in rain 500ml = 63.66mm rain = 2.51in rain 1l = 127.32mm rain = 5.01in rain 1 cup = 236.588 ml 1 qt = 946.353 l 1 cup = 1.19in rain = 30.12mm rain 2 cups = 2.37in rain = 60.25mm rain 1 qt = 4.74in rain = 120.49mm rain or: 1 inch rainfall == 199.5 ml - close to 200 ml 1. Find out if the gauge is accurate mechanically. Regardless of whether the bucket-tips are equal or not, feed it enough "rain" (at least the equivalent of 1 inch) so that any unequal bucket tips average out. Don't pour the water in too quickly, because overflow compromises accuracy. 2A. If the rain gauge mechanics are accurate but the bucket-tips are uneven, equalize the bucket-tips by adjusting one up and the other down. Go to step 3. 2B. If the rain gauge mechanics are high or low – that is, if one of the buckets tips sooner or later than the other – adjust the offset bucket to match the other. Go to step 3. 2C. If the rain gauge mechanics are inaccurate, but the bucket-tips are equal, adjust the buckets to tip sooner or later, each by the same amount. 3. Once the bucket-tips are equal, check for accuracy (step #1) and re-calibrate if necessary (step 2C). Perform these steps with the funnel in place. Some tips for perfectionists: The most accurate way to equalize the buckets is to count the number of drops of water it takes to tip each bucket. To do this, find a small container or hollow object (small test tube) that fills the buckets to near-tipping, then count the drops needed to complete the tipping. For the "high-volume" accuracy tests, fill each bucket with your container then use a squeeze-type squirt bottle to bring it to tipping. Do not squirt directly into the collection hole because the force of the stream may cause the bucket to tip prematurely. Finally, be aware that since the unit measures in metric units then converts to inches, there will be slight variances in measured amounts. For example, the unit will sometimes read 1.02 inches, which isn't even a multiple of 0.04.