Tips for using needle type moisture meters and needle free moisture meters
In many cases, it may be necessary to test the moisture content (% MC) of certain substances. Moreover, when directly testing the moisture content of materials, there are two main options - needle type water needle type moisture meter and needle free moisture meter. The use of Figure 1 moisture meter and needle free moisture meter is very suitable.
The needle moisture meter uses the principle of resistance to measure the moisture content in various materials. Since water is a conductor, materials such as wood, cotton, gypsum, and hay are all resistors, the easier current flows through the material, the wetter it becomes. For the sake of accuracy, it is important to ensure that the needle instrument is calibrated for the specific material being tested - different materials have different inherent current resistance.
On the other hand, needle less hygrometers use electromagnetic radio frequency to "scan" material samples to determine the presence of water. The fluctuation of electromagnetic waves is used to measure the amount of water in the sample. The accuracy of the needle less moisture meter is affected by the specific gravity (SG) of the scanned material, so it is necessary to calibrate the instrument for the SG value of that material. Specific gravity is a measure of the relative density of a material compared to another material (usually water).
Both needle and needle free hygrometers have their unique advantages and disadvantages, which may make them more or less suitable for specific humidity testing situations. When should a needle type moisture meter be used and when should a needle free moisture meter be used? The following is a broad scenario where one type of hygrometer may be better than the other.
Test large and flat surfaces, such as the entire floor
The needle free moisture meter is adept at quickly and effectively measuring the moisture content of large areas of the structure. Simply push the scanning board into the floor, read, lift, and repeat the scan in another position. The scanning board inspects a large area at once, and each inspection only takes a few seconds. This allows users to quickly scan very large areas of the structure with relative ease.
On the other hand, a needle hygrometer can only check for moisture in the small area between the contact needles. In addition, they need to delve deeper into the tested material to obtain comprehensive reading. This usually means that greater force is required to penetrate tougher materials, increasing strain and the risk of pin failure. A smaller testing area and additional effort can help increase the time and labor costs for measuring moisture on a large scale.
Selection: Needle less moisture meter
Testing for moisture in uneven surfaces and loose filling materials
A needle less hygrometer needs to be in full contact with a solid surface to provide accurate readings. If the scanning board cannot be placed completely flat on the tested material, the accuracy of the needle free hygrometer will be affected. In addition, if the scanned material is loosely packaged (such as for insulation or hay), the instrument may ultimately test the moisture content of the air between the material fibers.
On the other hand, needle hygrometers can be easily used to test materials with loose deposits or uneven surfaces. The important thing is the current in the tested material - as long as there is a path for the current to flow from one pin to another, the test can be completed. However, in order to test for moisture in fiberglass insulation materials, hay bales, etc., specialized electrodes may be required.
Selection: Needle moisture meter
Test for moisture in materials you do not want to damage
Needle less hygrometers are sometimes referred to as "non-invasive" or "non-destructive" hygrometers because they do not need to penetrate the surface of the material being tested to obtain accurate moisture content measurements. That's why many flooring professionals use needle less hygrometers to test the humidity of their hardwood flooring. By using a needle free instrument, the moisture content can be evaluated without damaging the hardwood floor.
On the other hand, needle hygrometers need to penetrate the surface of the material for appropriate testing. In applications that require protection of the surface condition of the final product, leaving pinholes, even small pinholes that are easily filled or filled with epoxy resin, is usually not satisfactory.
Selection: Needle less moisture meter
Determine the moisture distribution of the entire plate
When needle free moisture meters scan the moisture in the material, they can provide an average reading of all moisture in the scanning area. This means that if a moisture bag is detected, you will not know how deep it is. Alternatively, if the shell and moisture content of the material sample are different, you will not be able to understand the differences.
Needle moisture meters, especially those that use insulated needles, perform excellently in determining the moisture distribution in circuit boards. Using insulated pins, you can simply push the pins a few tenths of an inch, read the data, push them another inch, read again, and continue the process until the pins are fully inserted. The distribution of moisture in the board may be invaluable information for wood dealers as it can help them determine the curing method of the wood and adjust the kiln conditions accordingly.
