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Do I need seal fittings?

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    Do I need seal fittings?

    I have a Class I Div II area classification. There is an explosion-proof junction box that has several 110v XP Solenoid valves attached attached via a single conduit. These solenoids are within 10-12" of the JB. See the photo. I believe that the conduit entry into the JB should have a seal. Is this correct? Do the solenoids also need a seal where the conduits tie into them?

    Thanks in advance..........
    Jon

    Click image for larger version

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    #2
    For Div 2 (or Div 1) the solenoids would not require a seal fitting - they don't have any arcing or sparking components.

    Depending on what is inside the big junction box, there could be a seal required between the Killark box and the big junction box. What is in the big junction box? If it is just terminations then likely no seal required (and the box did not need to be XP). If more than that, then it probably needs a seal as you suggested.

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      #3
      Thanks for your response. Inside the large XP Junction box are some terminal blocks, a min-PLC, and a contactor. There are also some pushbuttons and a pilot light mounted in the cover. The contactor & pushbuttons are driving the requirement for the JB to be XP. If the solenoids (110v) have no arcing contacts or heat source as you point out, then I guess all I need is a seal at the JB. Right?

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        #4
        My opinion would be that a seal is required between the large XP junction box and the Killark round cover Tee fitting to maintain XP rating on the large XP jb, based on their being a contactor and PLC in the box. Based on 501.15(B)(1) and its reference to 501.15(A)(1). Is this a factory assembled skid of some sort (like a chromatograph or similar)? Not sure if the assembly might have a listing or approval to be assembled in the way that it is?

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          #5
          This is a Nitrogen package skid unit that was supposed to be designed to operate in a Class I Div II area classification.

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            #6
            Are you saying the xp box is being purged with nitrogen, I am going to assume not as usually outside air is used to purge a box with arcing devices. If not purged, then you would need a seal off to prevent combustible gases from entering the the box. Even if it was listed for XP environments, it will still need to be properly sealed were conduit is connected to it.
            The world is round, you will get there no matter what path you take.

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              #7
              Originally posted by rlundsrud View Post
              Are you saying the xp box is being purged with nitrogen, I am going to assume not as usually outside air is used to purge a box with arcing devices. ...
              It if fairly common for nitrogen to be used as the purge in industrial applications.
              Don, Illinois
              (All code citations are 2017 unless otherwise noted)

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                #8
                Originally posted by don_resqcapt19 View Post
                It if fairly common for nitrogen to be used as the purge in industrial applications.
                I have seen nitrogen used as a purge gas in class I div. I, but on div. II systems I have only seen outside air as a purge mechanism. I really just wanted to know if there was any type of purging system in place as that would have negated the need for a seal on the XP box. Thanks for the info though, I didn't realize it was that common.
                The world is round, you will get there no matter what path you take.

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                  #9
                  If the enclosure is purged, then no seal would be needed between the large enclosure and the T fitting. If the enclosure is not purged, a seal would be required between the large enclosure and the T fitting.
                  Don, Illinois
                  (All code citations are 2017 unless otherwise noted)

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                    #10
                    Originally posted by don_resqcapt19 View Post
                    If the enclosure is purged, then no seal would be needed between the large enclosure and the T fitting. If the enclosure is not purged, a seal would be required between the large enclosure and the T fitting.
                    I agree. It does not matter much if the box is XP or not, if it is being protected by being pressurized no seal is required anywhere.

                    It might be handy to reduce the amount of N2 used, but not required.
                    Bob

                    Comment


                      #11
                      Thanks for your responses. Just to clarify, the fittings & JB in the picture are part of a Nitrogen Skid which produces a source of nitrogen to be used on the platform. The XP JB is not pressurized, if it was then it wouldn't need to be XP. I originally felt that a seal was needed between the T fitting and the JB and the comments received from all have confirmed this.

                      Comment


                        #12
                        Multiple What ifs!

                        What if the area is classified Cl1 Div1 Grp D(methane) and the solenoid valve is 480V, in an explosion proof housing that does not indicate it is hermetically sealed, factory sealed or oil immersed. The installation is similar to the Jon K's picture, but with 2 solenoid valves connected to the Killark "T" box with flexible couplings approximately 12" in length...... and instead of the XP junction box, the Killark box is nipple'd into a seal off that seals the conduit leaving boundary.

                        I have read conflicting info regarding the solenoid valves being an arc producing device. Is the key words "normal operation" in 501.15,A,1? A solenoid can often stick in the non-energized position under abnormal conditions and overheat when energized.
                        If the solenoid does not require a seal and I am able to hold my conduit system between the solenoids and the boundary seal off within 18", the only seal off required would be the boundary seal?

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