According to the analysis of the in-use splice case, we found that the main reasons for the ingress of water in the fiber optic splice closure are as follows:
1.In the use of the fiber optic splice closure consists of two symmetrical and similar parts. There are two ways for the fiber optic splice closure to enter the water, one is the cable entry hole of the fiber optic splice closure, and the other is the contact end surface of the upper and lower parts. The former is sealed by wrapping a strip of sealant on the cable jacket. The seal on the end face is sealed by a rubber strip. The cable entrance hole is separated by the end face into two semicircles belonging to the upper and lower boxes. This results in cable entry. The sealing at the place and the sealing of the end face of the box interact and restrict each other. When construction workers are required to seal the cable entry L at both ends of the fiber optic splice closure with tape, the number of sealed tapes must be strictly used. When the number is too small, the feed through hole will create a gap and cause water ingress. When too much glue is tangled, both ends of the splice case will become high, and moisture will enter through the rubber strip from the connecting end surfaces of the upper and lower parts of the splice case. In addition, when there is more sealant on one side and less sealant on the other side, the heights at both ends of the splice case may be inconsistent, and gaps may be formed on the contact surfaces of the upper and lower case bodies, resulting in water ingress.
2.The use of sealant at the cable entry fiber optic splice closure is not reasonable. The sealing at the cable gland with the connector box is achieved by the sealant that is wrapped around the cable. This extrusion gives the sealant a pressure perpendicular to the cable but the adhesive is not in the axial direction of the cable. . This causes the sealant to extend along both sides of the optical cable after being pressed, so that the adhesive and the cable, the adhesive, and the case cannot be fully contacted, and a good sealing effect cannot be achieved.
3.Since the sealant is not under sufficient pressure and both ends are exposed, its viscosity and elasticity will degrade over time until it hardens.