The probe is intrinsically safe, the cable is also intrinsically safe; since the transmitter is located outside the explosion-proof area, is it still necessary to have an intrinsically safe design?
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It’s a split-type instrument; the probe is intrinsically safe, as is the cable. I install the transmitter outside the explosion-proof area – does that mean the transmitter also needs to be of the intrinsically safe explosion-proof type?
The transmitter does not need to be intrinsically safe, but a safety barrier must be added between the transmitter and the field; only then is it an intrinsically safe circuit.
Thank you, moderator. I have used safety barriers between field transmitters and DCS systems, but I have not used ones between transmitters and the sensors in the field. What type of safety barrier is generally suitable for such cases? PS: This meter is a common E+H split-type pH temperature meter; the electrodes collect pH and temperature signals and send them to the field transmitter. The cable connecting the electrodes to the transmitter is provided by the manufacturer and is a four-wire cable.
1. The PH probe has a intrinsically safe circuit; the safety barrier is located inside the transmitter, forming the intrinsically safe \"probe detection circuit\". You can take a look at the circuit diagram. 2. As for the explosion-proof measures used by the transmitter itself, it depends on the area where it is installed; there are Exd or E* options available ； If it is in a safe area, the transmitter body does not require explosion-proof certification. 3. The intrinsically safe approach for 1 is referred to as “associated,” and this is indicated with parentheses; check whether there are parentheses on the explosion-proof marking of the transmitter 4. Similar to PH, the signals from capacitive level sensors, electromagnetic flowmeters, and mass flowmeters are all processed by safety barriers built into the transmitters; since the detection circuits can be designed to be intrinsically safe, there is no need for explosion-proof designs – something that would be unnecessary and overly complicated. . . . @jiaguoyun
Every component in the circuit must be intrinsically safe; non-explosion-proof components can be used once one exits the explosive hazard area (for electrical systems isolated from the outside world in the control room)
Intrinsic safety is actually quite complicated: not only must the individual components be intrinsically safe, but an intrinsic safety cable, an intrinsic safety power supply, a safety barrier, and other elements are also required to form an intrinsic safety circuit. As the person above said, \"Every component in the circuit must be intrinsically safe.\"”