can i just use any sensor that i want as long as i use an approved I.S. barrier? QUOTE]
No, you cannot use just any sensor. If the sensor goes into a hazardous area (Class 1, Div 1 in the US) then your sensor needs to be either explosion proof or Intrinsically safe. Explosion Proof wiring is spec'd in the electrical code.
Instrinsic safety is achieved by a certification that the device is designed instrinsically safe, meaning its power useage and power storage falls under certain limits, and that an intrinsic safety barrier is used to prevent electrical faults in the safe area from getting into the hazardous area through the wiring which could create an arcing sparking ignition source.
So stick with something rated I/S or EXP, if the device is in a hazardous area.
As an example of sensors, I've used Milltronics (now Siemens) ultrasonics, and Milltronics' PROBE has 2 models - the regular one can shoot a longer distance because its energy is not limited. The I/S model PROBE doesn't shoot as far or update as often, because of energy restrictions designed into it. I have to use an I/S barrier with the I/S PROBE. PROBE won't work for you though, it has a 10" or 11" dead zone or blanking zone.
Dan
