Hi All,
I am new to this forum and I have a question concerning the design side of Intrinsically Safe devices.
In the past I have designed several devices that were submitted to Factory Mutual for approval under their FM3610 requirements for Class 1 Division 1 use. These past devices passed the FM approval process with few issues so I felt that I had a pretty good handle on the requirements. However, I don't do a lot of this on a day in and day out basis.
I recently designed a controller that is quite similar to these past designs. However, my customer wants to use their favorite UL NRTL rather than FM. They have submitted the device for review by this UL lab and they have run into all sorts of component issues that were never raised by FM.
In my past experience, FM applied test data that they had previously obtained and apparently made a judgment based on this data that there was not an issue in some of these circumstances. I will not get into all of the details since it could be a very lengthy discussion. However the one of the big issues is over the maximum surface temperature of small components. (ANSI 60079-11 clause 6.2 and 60079-0 clause 5.5)
I have suggested the they submit the device to Factory Mutual since I have heard in the past that UL requires a lot of component testing where FM, based on past experience, may not. I was wondering if anyone on the forum could comment on this.
Larry
I am new to this forum and I have a question concerning the design side of Intrinsically Safe devices.
In the past I have designed several devices that were submitted to Factory Mutual for approval under their FM3610 requirements for Class 1 Division 1 use. These past devices passed the FM approval process with few issues so I felt that I had a pretty good handle on the requirements. However, I don't do a lot of this on a day in and day out basis.
I recently designed a controller that is quite similar to these past designs. However, my customer wants to use their favorite UL NRTL rather than FM. They have submitted the device for review by this UL lab and they have run into all sorts of component issues that were never raised by FM.
In my past experience, FM applied test data that they had previously obtained and apparently made a judgment based on this data that there was not an issue in some of these circumstances. I will not get into all of the details since it could be a very lengthy discussion. However the one of the big issues is over the maximum surface temperature of small components. (ANSI 60079-11 clause 6.2 and 60079-0 clause 5.5)
I have suggested the they submit the device to Factory Mutual since I have heard in the past that UL requires a lot of component testing where FM, based on past experience, may not. I was wondering if anyone on the forum could comment on this.
Larry