Dear all,
I currently have a Foundation Fieldbus segment that was intended to be Instrinsically Safe (IS) and it consists of a trunk cable connected to a device coupler which then connects to five different spurs (two level transmitters and three pH transmitters). I discovered a few days ago that the pH transmitters do not pass IS assessment such that the maximum output parameters (U, I, P) of the device coupler exceed the maximum input parameters of the pH transmitters. Also, the maximum output parameters of the pH transmitters also exceed the maximum input parameters of the pH electrode downstream.
I subsequently discovered also that the pH transmitters, electrodes and the device coupler are all located in a non-hazardous area. I confirmed that the two level transmitters in the meantime are compatible with the rest of the loop.
I have now effectively mixed IS and non-IS loops to the same device coupler. I would like to know if FISCO standards explicitly forbid this or if I am OK as long as I abide by certain rules given that the "non-compliant" parts are in a safe area? Thank you and I look forward to your responses.
