In modern conditions of development of the poultry industry, the arrangement of an incubator is a very topical issue. To create a comfortable environment it uses various measuring devices. Thus, the change in temperature and humidity can be monitored using a psychrometer or hygrometer. Let us consider in detail the principle of their actions.
Principle of operation
As a tool for measuring humidity and temperature in a room, a psychrometer is a device that holds 2 mercury columnslocated independently of each other. They are called dry and wet thermometers.
Did you know? The first mercury thermometer was invented by the Italian doctor Santorio, who was born on March 19, 1561. While working in Europe, he studied the process of breathing, and conducted some of his experiments on himself. The inventor of the first practical hygrometer is Francesco Folly.
The principle of its operation is based on water's ability to evaporate, provoking the occurrence of temperature difference according to the psychrometer. The speed of this process depends on the level of humidity. The higher it is, the less will be the difference between the readings of thermometers. This is due to the fact that in the process of evaporation of water cools the tank in which it is located. 
Types of hygrometers
Depending on the design features, there are several types of this measuring device. Among them are weight and ceramic hygrometers, hair moisture meter, film sensor. Let us consider the description of each of them in more detail.
Successful incubation of eggs would be impossible if there were no stable temperature conditions. This process is provided by a special device - a thermostat that can be made by yourself.
Weight hygrometer
This measuring device is a system consisting of U-shaped tubes that are filled with a hygroscopic substance. Its property is the ability to absorb moisture released from the air. Through this system, a certain amount of air is drawn through the pump, after which its absolute humidity is determined. To do this, you need to calculate such indicators as the mass of the system and the volume of air that has been passed. 
Hair moisture meter
This device is a metal frame, on which there is a skimmed human hair stretched along. It is connected to the arrow, and its free end is equipped with a light load. Thus, depending on the degree of moisture, the hair is able to change its length, signaling this by a moving arrow. 
It should be noted that the hair moisture meter intended for home use has a small error. In addition, its fragile design can quickly break under mechanical action. In order to avoid this, it is recommended to hang the measuring device on the wall, and also to make sure that there are no vibrations in the chosen place, and that the sources of cold or heat are at least 1 m away. In case of hair contamination, it can be cleaned with a brush previously moistened with water.
Important! The best temperature regime for the operation of a hair moisture meter is a gap of -30 ... +45 degrees. In this case, the accuracy of the instrument will be 1% relative humidity.
Film sensor
This device is a vertical design. It consists of an organic film, which is a sensitive element. It is able to stretch or shrink depending on the increase or decrease in humidity, respectively. 
Learn how to choose an incubator and which models to give preference to, as well as familiarize yourself with the characteristics of the incubators: "Layer", "Cinderella", "Perfect hen", "Kvochka", "Nest-100", "Nest-200".
Ceramic
This device has the form of a clock, only the numbers shown on it are divisions of a mercury column, indicating the percentage of air humidity. The main element for its manufacture is the ceramic mass, which contains metal impurities of kaolin, silicon, clay. This mixture has an electrical resistance, the level of which is affected by the humidity of the air. 
How to choose a hygrometer
Before choosing a hygrometer, you need to consider that there is several types: wall, table, mechanical and digital. These devices differ not only in their technical characteristics, but also in terms of equipment, accuracy of indicators. In addition, they may have additional features such as a calendar, clock, alarm clock, comfort level indicator, etc.
Important! In the case of desktop placement of the hygrometer, it is necessary to take into account not only its dimensions, but also the angle of rotation of the device to the light source. This will provide more accurate data.
When studying the technical parameters of the sensor should pay attention to the relative and absolute pressure. Moreover, the choice of instrument should depend on the size of the incubator. So, if it is intended for more than 100 eggs, it is necessary to install a more powerful hygrometer.
Examples of the most popular models:
- MAX-MIN - has a plastic case, is equipped with a thermometer, clock and alarm clock, and also allows you to mount additional sensors. In case of a change in the humidity level, it beeps.
- Stanley 0-77-030 - has an LCD display and a robust case, protected from mechanical damage, but its cost is extremely high.
- DC-206 is designed for an incubator of a small size and can quickly fail with mechanical damage.
- NTS 1 is a compact electronic device that has an LCD display and is equipped with a calendar, a clock and an alarm clock.
How to make a hygrometer yourself
An alternative to a device purchased at the store can be a homemade hygrometer. To make it, you will need to acquire some materials and tools, as well as learn step-by-step instructions.
Read also about the manufacture of the incubator with your own hands, ventilation, temperature control and disinfection of the incubator.
Materials and tools
In order to independently construct a psychrometer, you must purchase two thermometers. In addition, you will need a piece of cloth and a small cup with distilled water.
Such liquid can be obtained by purification from impurities or simply purchased in the store. Do not forget about the panel for mounting. It can be made of plastic, wood or other materials.
Did you know? The largest thermometer operating in the territory of Eurasia is considered to be a device installed in 1976 in the Ukrainian city of Kharkov, having a height of 16 m.
Step by Step instructions
To make the fixture manually, you will need to complete the following actions:
- Attach 2 thermometers to the panel, placing them parallel to each other.
- Under one of them should be put a container with water.
- The mercury tank of this thermometer must be wrapped in cotton fabric and attached, tied with thread.
- Dip the edge of the fabric into the water for 5-7 cm.
Thus, the thermometer, over which this manipulation was carried out, will be called "wet", and the second - "dry", and the difference between their indicators will show the level of humidity.
Important! Sometimes, to increase the humidity in the incubator, you can simply spray the eggs with water, but this procedure is appropriate only for waterfowl. For other representatives of birds suitable humidity level of 50-60%.
Video: air humidity measurement
Experienced poultry farmers choose for themselves the most effective way to measure humidity, guided by the size of the incubator. In addition, in modern conditions of market economy development, the choice still depends on financial possibilities.
