Having designed intrinsically safe systems in the past, I would point you towards using an instrument engineering contractor or contact your local MTL instruments representative who should be able to assist you in specifying the safety barriers or isolators (try www.mtl-inst.com).
For all...
Alternative flame detection equipment could include flame detectors as manufactured by MSA, Detronics, and Thorn.
The principles involve include UV/IR flame detection and are regularly used in the oil and gas business.
Although I am not overly familar with NFPA, if you contact companies like...
Not sure about the recalibration of the pressure transmitter below the minimum span, but I would recommend you discuss with the manufacturer for best advise.
For the orifice plate thickness, forward your process data to an orifice plate manufacturer and they will advise the thickness of the...