Regarding thermocouples, the issue of explosion protection for thermal resistors

Exd II, flameproof, Zone II; E*a II, intrinsically safe, Zone II

There are 2 explosion-proof types, indicating that there is a difference in current level. .

For this thing, if there is a safety barrier, a regular waterproof junction box should suffice.

Is the poster sure there are intrinsically safe thermoresistors and thermocouples?

Reply to 1# ydysj: Is the poster sure there are intrinsically safe thermoresistors and thermocouples?

This post was last edited by hwindforce on 2010-10-15 at 10:21. Many manufacturers offer intrinsically safe thermoresistors and thermocouples, but it’s just a gimmick. Thermoresistors and thermocouples are simple devices that do not require intrinsically safe certification at all.

Thermocouples and thermal resistors are both simple components; there’s no need for intrinsically safe certification: lol

Thermoresistors and thermocouples, based on their measurement principles, generate low-power signals; in the case of thermocouples, these are mV-level signals that are inherently intrinsically safe signals, so they will definitely pass the intrinsically safety certification. But everything I’ve come across is certified, and I’ve never paid attention to it; personally, I don’t think it’s necessary.

ExdII: Flameproof, Zone II. E*aII: Intrinsically safe, Zone II. Both platinum thermoresistors and E-type thermocouples use only very small currents, so they probably don’t require intrinsically safe certification~

Actually, the original poster might not have expressed themselves clearly. When it comes to explosion protection, it definitely refers to the entire set of instruments. In my opinion, the person who posted this must have come into contact with an armored integrated temperature sensor (thermistor/thermocouple + transmitter module + housing). Therefore, when used in chemical plants, explosion-proof certification is required. Generally speaking, explosion protection relates to two aspects: 1) temperature transmitter modules (however, I have only worked with intrinsically safe circuit designs, so such modules are safe by nature; there are also requirements for explosion isolation – in other words, the enclosure must be able to prevent explosions within the internal circuits) ； 2 refers to the object of the entire instrumentation set; generally, 316 stainless steel marked with the EX symbol is sufficient to achieve explosion protection. Note: Intrinsic safety type – refers to the circuit design aspect, where the current itself cannot cause an explosion; hence the name – intrinsic safety type (it is safe by nature). Flameproof type – the focus is on the material of the enclosure, which must be well-sealed and resistant to pressure. The above are all based on my several years of experience. For reference only.