3.2.2 Rat prevention test

Mice, as a highly reproductive and vital rodent, widely live in various regions of the world. Due to their well-developed and continuously growing front teeth, rodents have a habit of biting objects to maintain their sharp teeth.

failure mechanism

The unique smell of plastic makes it a common target for rodents to bite, and whether in wild or human activity areas, mice have a strong ability to damage wire and cable sheaths or insulation layers. Especially in cases where field mice bite on cables laid in the wild, causing cable failure and communication interruption, and there are also cases where wires in urban houses are bitten by mice and fail.

Mice can also bite plastic items such as rodent proof bags inside outdoor cabinets. Therefore, plastic materials such as cables used outdoors need to be designed to prevent rodent bites and undergo reliability verification through rodent proof tests.

Rat proof design

Cable: 1. Armored cable, making it difficult for mice to bite, but the disadvantage is high cost;

2. Adding taste stimulating substances such as chili powder can make it unbearable for mice to bite, but the disadvantage is that mice will still bite;

3. There have been successful attempts to add anti rodent agents and other olfactory stimuli to make mice smell and not want to bite.

Rat proof bag: harder materials can be used to prevent mice from biting; Alternatively, materials with added rodent repellents can be used to prevent mice from biting.

Test standards

At present, there are no standards for the testing methods of rat bite resistance both internationally and domestically, and even in the industry, there is no widely recognized method or standard. At present, some domestic communication and cable manufacturers have conducted some work on exploring methods for rodent resistance performance testing. Below is a recommended rodent resistance testing method that refers to domestic and foreign animal testing methods and is jointly explored by animal testing technicians in the laboratory:

1. Test material production: Prepare the sample according to the GB/T8815-2002 method for specimen preparation, with a specification of 150mm × 20 mm × A 3mm test piece.

Alternatively, complete machine products such as outdoor cabinets can be used, and mice can be placed in actual accessible areas during testing.

2. The weight of the experimental equipment and animals ranges from 250 to 300 grams. The male SD rats have a PP plastic box with a stainless steel mesh cover and a cage with a height of 250mm, a length of 600mm, and a width of 400mm. The bottom and walls of the cage are made of PP plastic, and the top is made of stainless steel mesh cover and equipped with a water feeder.

3. The experimental steps include selecting SD male rats and randomly sampling them into cages, with 5 rats per cage; Insert the test pieces from the top of the cage into the cage, tightly tie them with fine copper wire on the stainless steel mesh cover near the feeding point. The exposed part of the test pieces outside the cage should not exceed 20mm. Three test pieces should be hung in one cage, and evenly arranged in the width direction of the cage, with an interval of approximately 80mm. During the experiment, rats were supplied with normal water and food (or no food was placed to verify their biting behavior when hungry). Observe the activity and diet of rats every day, as well as the situation of the sample being bitten by rats after the end of the experimental cycle.

4. The test time is 7 days.

Example:

According to the above method steps, ordinary cable materials 1-a), 2-a), and 3-a) were selected as blank controls, as well as rodent resistant cable materials with special rodent resistant agents added (simulated natural plant ingredients artificially synthesized rodent resistant agents added) and rodent resistant cable materials with high propylene glycol rodent resistant agents added. Three sets of samples were subjected to a seven day rodent resistant test. The test samples were grouped and numbered as follows, and placed in numbers 1) and 2), respectively, 3) Conduct experiments in a rat cage:

1) 70 ℃ PVC material

1-a) Ordinary 70 ℃ PVC material

1-b) Adding high propylene 70 ℃ PVC material

1-c) Add special rodent repellent 70 ℃ PVC material

2) MDPE material

2-a) Ordinary MDPE material

2-b) Adding High Propylene MDPE Material

2-c) Adding special rodent repellent MDPE material

3) Low smoke and halogen-free fuel

3-a) Ordinary low smoke halogen-free fuel

3-b) Adding High Propylene Low Smoke Halogen Free Fuel

3-c) Add special rodent repellent low smoke and halogen-free fuel After a seven day experiment, the results are as follows:

*During the experiment, no poisoning or death was found in the tested rats, and they were able to move freely and had a normal diet.

*The degree of sample biting is shown in the table below

From the experimental results, it can be seen that the ordinary cable material (blank sample) without the addition of rodent repellent was severely bitten by rats, and the test piece was only left with the fixed part on the mesh cover. MDPE material, due to its hard material, is better than PVC and halogen-free fuel, but the biting situation is still relatively obvious; The cable material added with high propylene anti rodent agent has a slight anti rodent effect. Compared with the blank control samples 1-a), 2-a), and 3-a), the biting situation has improved, but there are obvious defects on the test pieces. The MDPE sample with the highest hardness has also been bitten all around, showing an irregular serrated shape; The test results of the anti rodent cable material with artificial synthetic anti rodent agents added to simulate natural plant components are relatively ideal, with only a few shallow tooth marks on the three samples and no obvious biting phenomenon.

3.2.3 Ant prevention test

Ants are the most common and numerous insect species on Earth, belonging to the phylum Arthropoda, Insecta, and Hymenoptera. Although it only has one family (Ant family), there are over 360 genera under it, estimated to be over 14000 species, with around 300 species in China. Ants can live in any place with their living conditions, and are the strongest creatures in the world to resist natural disasters. They are widely distributed, from deserts to forests, from tropical to cold regions, and from plains to high mountains.

failure mechanism

Ants love sweet food very much, and they are very sensitive to the smell of honey and sugar. Sweet food can provide energy for various activities of ants. However, they do not only eat sweet food. Ants are omnivorous animals with diverse feeding habits. Various animal and plant corpses, as well as organic residue, can become ants' food, such as dead insects and plant seeds, which are also important food for ants.

Ants not only cause harm indoors, such as stealing and polluting food, affecting people's lives, biting and attacking humans, and spreading diseases. Moreover, it can also cause malfunctions in outdoor electronic communication products, such as biting off organic matter on circuit boards, gathering and blocking air ducts, causing high-temperature faults, or producing secretions that cause corrosion and short circuits.

Ant resistant design

Cutting off its route is the simplest and most effective method.

In actual use of the product, it was found that ants are particularly interested in wireless RF module products, and there have been multiple failures of this product in the market. However, other outdoor wired access network products have not been found to have caused failures caused by ants. In the later stage, all wireless RF modules for outdoor applications met the protection standard of IP55, completely cutting off the route of ants entering the module, and the product did not experience similar failures again.

Test standards

At present, there is no standard for anti ant testing methods both internationally and domestically. Some domestic communication manufacturers have conducted some work on exploring anti ant performance testing methods. Below is a recommended anti ant testing method that refers to domestic and foreign animal testing methods and is jointly explored with animal testing technicians in the laboratory:

1. Test sample: Using whole machine products, such as outdoor integrated modules and product modules inside outdoor cabinets, the testing should simulate the actual application of emission power to generate high-frequency and high-temperature environments.

2. Test equipment and animals: Recommended outdoor aggressive ants for insect laboratories, using PP plastic box test cages. The bottom and walls of the test cages are made of PP plastic, and the top is covered with stainless steel mesh or PP plastic, and equipped with a water feeder.

3. The test steps include selecting several ants and placing them in the test cage. The sample is then placed in the test cage, and the power is normally transmitted when energized. During the experiment, ants were provided with normal drinking water and no food was placed to verify their biting behavior on the product in a hungry state. Observe the activity and diet of ants every day, as well as the sample being bitten by ants after the end of the experimental cycle.

4. Test time: The recommended test time is 7 days, and it can also be extended to observe the attack of ants on the sample.