humidity in shade house - Orchid Board

mlrao · #1 11-01-2006, 06:49 AM

How canyou measure humidity in shade hose with 50% shade net covered on top and all sides with out using sophisticated techniques and equipments and how can u control humidity desirable levels in shade house. i am from India

ScottMcC · #2 11-01-2006, 07:07 AM

you should be able to get a hygrometer (humidity meter) for fairly cheap. sure, the really nice ones are expensive, but I got a combined thermometer/hygrometer for about $20 here in the US (at Bed Bath and Beyond). I have no idea what the Indian equivalent would be, but it can't be too bad...

Shadow · #3 11-01-2006, 07:11 AM

I have an article about this issue. The author suggests to use two termometers - dry and damp and calculate the level of humidity on basis of the differences between their two readings with the use of special table. I didn't try it because I didn't find two identical termometers with the same temperature readings yet. So, can't guarantee the accuracy of this method. But I heard it is quite good and more accurate than some hygrometers. If you are interested I can translate this article (it is in Russian), but it can take approximately two days.

mlrao · #4 11-01-2006, 10:30 AM

ya u can translate and send me to madirajul@yahoo.com

Shadow · #5 11-02-2006, 10:23 AM

I've sent it to you, but I will post the text here too. May be somebody else will need it. I cannot post the table for calculations here, so if somebody need one I can e-mail you. The degrees in table are Celsius.

Shadow · #6 11-02-2006, 10:24 AM

Measuring air humidity.
Author: Kudryapin N.D.

If you grow orchids it is important to watch air humidity. You can measure the relative air humidity using special equipment called hygrometer. Also, you can make the air humidity measuring device by yourself using 2 thermometers. One thermometer should be dry, another one – damp. Due to the constant water evaporation the readings of the damp thermometer are always lower than the readings of the dry one. If you know the difference between these two readings you can calculate the relative air humidity. It is important to choose the thermometers that show the same readings when they are dry. Only in this case the calculations will be accurate. The damp thermometer should be damp, but it shouldn’t be in water. You can wrap it up in one layer of fabric and sink in water the lower end of that fabric. If you use hard water the salts will be depositing on fabric and in this case you should change the fabric every 2 or 3 months. The disadvantage of this method is the necessity of use of the special table. The advantage is the high accuracy. Also, two thermometers are cheaper than hygrometer and they don’t need batteries.
Notes. You should find the reading of the dry thermometer in the left red column. Then, find the reading of the damp thermometer in the same row. The corresponding relative air humidity will be in the blue row (in the same column as damp thermometer reading).