一、IP 防护等级怎么读
IP 代码由两位数字组成：第一位表示防固体异物（含防尘），第二位表示防水。数字越大防护能力越强。
- 第一位常见等级：5 为防尘（不完全密封但进入的粉尘量不影响运行），6 为尘密（完全防止粉尘进入）。
- 第二位常见等级：4 防溅水，5 防喷水，6 防强烈喷水，7 防短时浸水，8 防持续浸水，9K 防高压高温喷射水。
- 常见组合：室内一般环境 IP54 或 IP65；户外与冲洗场合 IP66 或 IP67；可能长期浸水的场合 IP68。
选型时要结合实际：户外仪表除 IP 等级外，还要考虑防紫外线、遮阳罩、电缆引入口的密封与呼吸阀（防止凝露）。
二、防爆标志怎么读
常见防爆型式：
- 隔爆型 Ex d：把可能产生火花的部件放在能承受内部爆炸并阻止传播的外壳内。
- 本质安全型 Ex ia / Ex ib：限制电路能量，使正常或故障状态下都不能点燃爆炸性混合物。本安仪表需配套安全栅。
- 增安型 Ex e：在正常运行中不产生火花或高温的部件上加强安全措施。
- 正压型 Ex p：外壳内保持保护气体正压，阻止外部爆炸性气体进入。
其他关键参数：
- 设备类别：I 为煤矿，II 为除煤矿外的爆炸性气体环境，III 为粉尘环境。
- 气体组别：IIA、IIB、IIC，IIC 要求最高（如氢气、乙炔）。
- 温度组别：T1 至 T6，T6 允许的表面温度最低（约 85℃），组别数字越大要求越严。
- 区域划分：气体环境常分为 Zone 0 / 1 / 2，粉尘环境为 Zone 20 / 21 / 22，区域数字越小危险程度越高。
三、选型核对顺序
- 先由设计或安全部门确定危险区域划分与气体/粉尘类别；
- 按区域选择允许的防爆型式（例如 0 区通常要求 Ex ia）；
- 核对气体组别与温度组别不低于现场要求；
- 确认仪表具备对应标准与地区的防爆合格证，且证书覆盖实际型号；
- 确认配套完整性：电缆引入装置、接线盒、挠性连接管、接地、安全栅等都需满足防爆要求；
- 本安系统需核对安全栅与现场仪表的参数匹配（电压、电流、电容、电感）。
四、容易忽略的点
- 只买了防爆仪表，用了普通电缆引入装置，整体验证失效；
- 本安仪表未配安全栅，或安全栅参数不匹配；
- 防爆合格证只覆盖主机，未覆盖可选模块或附件；
- 安装时未按要求拧紧螺纹、未做等电位连接；
- 后期更换部件时混用了非防爆件。
防爆涉及安全合规性，具体项目请务必以设计单位与安全规范为准。我们可以协助核对仪表型号对应的防护与防爆参数，并按要求提供配套件清单。
1. Reading IP codes
An IP code has two digits: the first is protection against solid objects and dust, the second against water. Higher numbers mean better protection.
- First digit: 5 is dust-protected (not fully sealed, but ingress does not impair operation); 6 is dust-tight.
- Second digit: 4 splashing water, 5 water jets, 6 powerful water jets, 7 temporary immersion, 8 continuous immersion, 9K high-pressure and high-temperature water jets.
- Common combinations: IP54 or IP65 for general indoor use; IP66 or IP67 outdoors and for washdown; IP68 where prolonged immersion is possible.
Match the code to reality: outdoor instruments also need UV resistance, a sun shield, sealed cable entries and often a breather drain to prevent condensation.
2. Reading Ex markings
Common protection types:
- Flameproof Ex d: parts that could spark are enclosed in a housing that withstands an internal explosion and prevents transmission.
- Intrinsic safety Ex ia / Ex ib: circuit energy is limited so that neither normal nor fault conditions can ignite the atmosphere. IS instruments require a safety barrier.
- Increased safety Ex e: additional measures on parts that do not spark or overheat in normal service.
- Pressurised Ex p: the enclosure holds a protective gas at positive pressure to keep the atmosphere out.
Other key parameters:
- Equipment group: I for mining, II for gas atmospheres other than mining, III for dust.
- Gas group: IIA, IIB, IIC - IIC is the most demanding (hydrogen, acetylene).
- Temperature class: T1 to T6; T6 allows the lowest surface temperature (about 85 C), and a higher number is stricter.
- Zones: gas atmospheres are divided into Zone 0 / 1 / 2 and dust into Zone 20 / 21 / 22; a lower number means higher hazard.
3. Order of checks
- Have the designer or safety authority define the zone classification and the gas or dust group.
- Choose a protection type allowed for that zone (Zone 0 normally requires Ex ia).
- Confirm the gas group and temperature class are at least as demanding as the site requires.
- Confirm the instrument holds an explosion protection certificate for the applicable standard and region, covering the exact model.
- Confirm completeness of the assembly: cable glands, junction boxes, flexible conduits, earthing and barriers must all comply.
- For IS systems, check that barrier and field instrument parameters match (voltage, current, capacitance, inductance).
4. Points often missed
- An Ex instrument fitted with an ordinary cable gland invalidates the assembly.
- IS instruments installed without a barrier, or with mismatched barrier parameters.
- A certificate covering the main unit but not the optional modules or accessories.
- Threads not tightened to specification or equipotential bonding omitted.
- Non-Ex parts mixed in during later replacement.
Explosion protection is a safety compliance matter: always follow the design authority and applicable standards for a specific project. We can help confirm the protection and Ex parameters of a given model and supply the matching accessory list.