recondaddy
Member
Hello,
I have a client who has recently decided to retrofit an existing machine to ensure intrinsic safety. I have very limited experience with IS, so I wanted to run a question by you good folks.
The only current-carrying devices in the hazardous area are some SMC auto switches to indicate cylinder extension and retraction.
The client looked at the data sheet for the sensors and found the max current carried by the sensors to be 40 ma @ 24VDC. Looking at the ignition curves, he says this is well below the voltage+current that would cause an ignition.
I have recommended isolation barriers and NAMUR sensors, but the client thinks they are unnecessary because of the ignition curves. I explained that under normal operation, his thinking makes sense, but if the sensor fails, you may have a lot more than 40 mA entering the hazardous area.
Is my thinking correct, and is there anything more I should explain to him?
Thanks for your help!
I have a client who has recently decided to retrofit an existing machine to ensure intrinsic safety. I have very limited experience with IS, so I wanted to run a question by you good folks.
The only current-carrying devices in the hazardous area are some SMC auto switches to indicate cylinder extension and retraction.
The client looked at the data sheet for the sensors and found the max current carried by the sensors to be 40 ma @ 24VDC. Looking at the ignition curves, he says this is well below the voltage+current that would cause an ignition.
I have recommended isolation barriers and NAMUR sensors, but the client thinks they are unnecessary because of the ignition curves. I explained that under normal operation, his thinking makes sense, but if the sensor fails, you may have a lot more than 40 mA entering the hazardous area.
Is my thinking correct, and is there anything more I should explain to him?
Thanks for your help!