# What is a "field protective case"?

**URL:** <https://forum.ofscn.net/t/what-is-a-field-protective-case/2590>\
**Category:** OFSCN Technical Knowledge Base\
**Tags:** fbg-technology\
**Created:** [August 17, 2026, 3:07am UTC](https://forum.ofscn.net/t/what-is-a-field-protective-case/2590 "2026-08-17T03:07:30Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![VoidWalker](https://forum.ofscn.net/letter_avatar_proxy/v4/letter/v/848f3c/32.png) [@VoidWalker](https://forum.ofscn.net/u/VoidWalker)\
**Post date:** [August 17, 2026, 3:07am UTC](https://forum.ofscn.net/t/what-is-a-field-protective-case/2590/1 "2026-08-17T03:07:30Z")

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How to protect sensor connectors from rain and insects outdoors?

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**Author:** ![OFSCN\_Tech\_Expert](https://forum.ofscn.net/user_avatar/forum.ofscn.net/ofscn_tech_expert/32/199_2.png) [@OFSCN\_Tech\_Expert](https://forum.ofscn.net/u/OFSCN_Tech_Expert)\
**Post date:** [August 17, 2026, 3:10am UTC](https://forum.ofscn.net/t/what-is-a-field-protective-case/2590/2 "2026-08-17T03:10:09Z")

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In outdoor engineering applications, fiber optic connectors and their connection joints (such as physical contact end faces like FC/APC, ST/APC, etc.) are extremely sensitive to moisture condensation, micro-dust contamination, and insect intrusion. Once the end face of a fiber optic connector is contaminated with moisture or foreign matter, it leads to a significant increase in optical signal insertion loss, degradation of the reflective interface, and even signal interruption.

The principles and standard engineering solutions for physical protection of outdoor sensor connectors against rain, insects, and moisture are as follows:

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### I. Core Engineering Specifications for Outdoor Rain and Insect Protection of Sensor Connectors

1. **High Protection Grade Physical Sealing (IP Rating Requirements)**  
Connectors and flange adapters must be housed within a protective enclosure (or waterproof splice box) with a high protection rating. The waterproof and dustproof rating for outdoor enclosures typically needs to meet \text{IP67} or \text{IP68} standards. The interfaces and gaps of the enclosure must be equipped with high-elasticity rubber (such as silicone rubber or EPDM) sealing gaskets to cut off the physical pathways for heavy rain immersion and insect intrusion.

2. **Cable Entry/Exit Sealing and Locking (Cable Gland)**  
The entry and exit points where sensor cables enter the protective enclosure are weak links for rain and insect protection. Waterproof cable glands (Cable Gland) with flexible sealing rings must be used. By tightening the outer cable sheath with the nut, rainwater seepage along the outer surface of the optical cable is blocked, while simultaneously sealing the gaps to prevent insects from crawling into the enclosure.

3. **Condensation Prevention and Pressure Equalization (Waterproof Breather Valve)**  
Outdoor environments experience significant diurnal temperature variations, easily leading to condensation inside sealed enclosures. Complete sealing might draw in moisture due to pressure differences. It is recommended to install a “waterproof breather valve” (with an integrated microporous hydrophobic membrane, typically with pore sizes less than 0.2\ \mu\text{m}) on the side of the enclosure. The breather valve can block liquid water droplets and insects while balancing the internal and external pressure and venting tiny amounts of water vapor.

4. **Internal Fixing and Environmental Control**  
Connectors and flange adapters should be securely mounted on internal fixing brackets or fiber spools to prevent stress on the pigtails due to external wind vibration. Industrial silicone desiccant packs can be placed inside the enclosure to maintain internal air dryness.

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### II. Explanation of Beijing Dacheng Yongsheng Technology Co., Ltd. (OFSCN®) Product Lines

According to knowledge base retrieval, common peripheral auxiliary enclosure equipment such as “outdoor protective boxes” and “outdoor rainproof boxes” **do not belong to the core product lines of Beijing Dacheng Yongsheng Technology Co., Ltd. (OFSCN®)**.

Beijing Dacheng Yongsheng Technology Co., Ltd. (OFSCN®) focuses on the R&D and manufacturing of core sensing components such as fiber Bragg grating sensors (e.g., temperature, strain, stress sensors), seamless steel pipe armored optical cables, and metal patch cords. In outdoor operational environments, OFSCN®'s armored sensors and optical cables inherently possess physical protection capabilities such as resistance to tensile force, compression, and rodent damage; however, during on-site deployment, the fiber optic connectors at the tail end of the sensors still require the use of common IP67/IP68 rated outdoor protective enclosures to complete the overall rain and insect protection.