Mechanical Ice Cube Relays

[adam garcia]

When using Ice Cube Coil Relays in a Control Panel(PLC) rated for clss1 div2 area, do the relays have to be class1 div2? Or can they just be Hermetically Sealed?

 

[jap]

I guess I don't understand the question.

Are you building a control panel and installing Ice Cube relays in the enclosure along with a PLC Controller?

Is the enclosure that the relays and PLC going into Class 1 Div 2 rated?

 

[weressl]

When using Ice Cube Coil Relays in a Control Panel(PLC) rated for clss1 div2 area, do the relays have to be class1 div2? Or can they just be Hermetically Sealed?

If the relay contacts are hermetically sealed, they most likley be rated for Class I, Div. 2. (There would be no toher reason to go into the trouble of emloying hermetically sealed contacts; a costly proposition.) The relay would not need to be listed though.....

 

[adam garcia]

I guess I don't understand the question.

Are you building a control panel and installing Ice Cube relays in the enclosure along with a PLC Controller?

Is the enclosure that the relays and PLC going into Class 1 Div 2 rated?

Yes, along with the PLC, the relays are for some solenoid valves controlling on/off valves on a gas plant skid.
Yes the Control Panel is rated for Class 1 Div 2.

 

[adam garcia]

If the relay contacts are hermetically sealed, they most likley be rated for Class I, Div. 2. (There would be no toher reason to go into the trouble of emloying hermetically sealed contacts; a costly proposition.) The relay would not need to be listed though.....

Excellent, thank you very much weressel

 

[jap]

If the relays are installed in a Class 1 Div 2 enclosure with appropriate seals installed to meet the
requirements for an enclosure with arc producing devices, why would the contacts need to be hermetically
sealed at all?

 

[weressl]

If the relays are installed in a Class 1 Div 2 enclosure with appropriate seals installed to meet the
requirements for an enclosure with arc producing devices, why would the contacts need to be hermetically
sealed at all?

You're missing the point. His intent is to install all non-arc/heat producing devices so there would be no seals necessary.

 

[kwired]

You're missing the point. His intent is to install all non-arc/heat producing devices so there would be no seals necessary.

Maybe I am missing something, but I thought from what is said in OP that these are to go inside an enclosure that is already rated for the classification, and apparently has at least a PLC inside the enclosure also that would probably require a rated enclosure. If so why spend extra on relays that are hermetically sealed?

When using Ice Cube Coil Relays in a Control Panel(PLC) rated for clss1 div2 area, do the relays have to be class1 div2? Or can they just be Hermetically Sealed?

 

[weressl]

Maybe I am missing something, but I thought from what is said in OP that these are to go inside an enclosure that is already rated for the classification, and apparently has at least a PLC inside the enclosure also that would probably require a rated enclosure. If so why spend extra on relays that are hermetically sealed?

Yep, you do. There are many PLC's that are rated for Class I, Div. 2, so they can be mounted in ordinary enclosures. There are also a host of pilot lights and pushbuttons that are listed the same. So it is quite common to assemble control panels in an ordinary NEMA 1 enclosure and use them in a Class I, Div. 2 environment.

Since all of my applications are outdoors, I rather use purged NEMA 4X panels as exposing even rated components to the corrosives would quickly render them useless. Although the sealed contacts themselves are protected, but all the terminals and connections are open to corrosion damage not to mention the mechanical parts of relays and pushbuttons.

 

[jap]

I guess you and I are missing the point Kwired,,,,,, altough I dont think we are.

 

[jap]

If you have an enclosure that is Class 1 Div 2 rated with the proper seals there is no need for hermetically sealed relays.

 

[weressl]

If you have an enclosure that is Class 1 Div 2 rated with the proper seals there is no need for hermetically sealed relays.

If you have hermetically sealed relays there is no need for seals.

But I'll humor you.

Let's say that we construct a panel that contains a PLC and some terminal blocks and a handful of relays. Conservatively estimating the enclosure would be about 8" deep, 24" wide and 36" tall. Since it contains arcing components it would need to be an enclosure that is listed for Class I, Div. 1 location and of course would require that every entry made into that box be made via and XP seal. A true monster....

Or you can select components that are either listed for Cl. I, Div. 2 installation, such as PLC, or does not have either open arcing or heat producing components, such as relays with hermetically sealed contacts, that do not require a listed enclosure in Class I, Div. 2 locations.

http://www.ab.com/en/epub/catalogs/12768/229240/229266/229661/3087128/484196/Introduction.html
http://www.ab.com/en/epub/catalogs/12768/229240/229244/2531085/229753/Introduction.html

The latter construction will save you several thousand $s.

 

[realolman]

If you have the right box, does it matter what's inside? Would t it be easier to get the right box?
Although I guess if you were going to operate this stuff with the door open for some reason....

 

[weressl]

If you have the right box, does it matter what's inside? Would t it be easier to get the right box?
Although I guess if you were going to operate this stuff with the door open for some reason....

It's only money....I guess if you operate like the Government does, it doesn't matter.

 

[kwired]

If you have hermetically sealed relays there is no need for seals.

But I'll humor you.

Let's say that we construct a panel that contains a PLC and some terminal blocks and a handful of relays. Conservatively estimating the enclosure would be about 8" deep, 24" wide and 36" tall. Since it contains arcing components it would need to be an enclosure that is listed for Class I, Div. 1 location and of course would require that every entry made into that box be made via and XP seal. A true monster....

Or you can select components that are either listed for Cl. I, Div. 2 installation, such as PLC, or does not have either open arcing or heat producing components, such as relays with hermetically sealed contacts, that do not require a listed enclosure in Class I, Div. 2 locations.

http://www.ab.com/en/epub/catalogs/12768/229240/229266/229661/3087128/484196/Introduction.html
http://www.ab.com/en/epub/catalogs/12768/229240/229244/2531085/229753/Introduction.html

The latter construction will save you several thousand $s.

Maybe I misunderstood, but I thought the OP already had a rated enclosure, so why spend even more on sealed relays? Otherwise I fully understand what you are saying.

 

[weressl]

Maybe I misunderstood, but I thought the OP already had a rated enclosure, so why spend even more on sealed relays? Otherwise I fully understand what you are saying.

OP: "a Control Panel(PLC) rated for clss1 div2 area"

That term alone will not describe what is the panel construction. First of all 'rated' itself is meaningless. Rated by whom? Three different constructions COULD be acceptable in Class I, Div. 2 environment.

1. Enclosure listed for Cl. I, Div. 1 where the internal components have almost no restriction. The almost comes in when the device is heat producing, where it has to be assured that there is sufficient heat dissipation so that the externals of the enclosure does not reach 80% of the AIT in consideration.
2. An ordinary enclosure with NFPA 497 Type Z purging can contain the same equipment with the saem stipulation as in 1.
3. An ordinary enclosure can contain components that produce no open arcing device - hence hermetically sealed relays - and heat producing devices that subject to the same restriction as in 1.

Granted, I gave credit to the OP that he would NOT be asking about the listing of the ice-cube relays for Cl. I, Div. 2 unless he is dealing with #3 panel type installation. (He is in my neck of the woods, and folks around here are very familiar with stuff like that.)

 

[kwired]

OP: "a Control Panel(PLC) rated for clss1 div2 area"

That term alone will not describe what is the panel construction. First of all 'rated' itself is meaningless. Rated by whom? Three different constructions COULD be acceptable in Class I, Div. 2 environment.

1. Enclosure listed for Cl. I, Div. 1 where the internal components have almost no restriction. The almost comes in when the device is heat producing, where it has to be assured that there is sufficient heat dissipation so that the externals of the enclosure does not reach 80% of the AIT in consideration.
2. An ordinary enclosure with NFPA 497 Type Z purging can contain the same equipment with the saem stipulation as in 1.
3. An ordinary enclosure can contain components that produce no open arcing device - hence hermetically sealed relays - and heat producing devices that subject to the same restriction as in 1.

Granted, I gave credit to the OP that he would NOT be asking about the listing of the ice-cube relays for Cl. I, Div. 2 unless he is dealing with #3 panel type installation. (He is in my neck of the woods, and folks around here are very familiar with stuff like that.)

I quoted the OP earlier, I will quote it again:

When using Ice Cube Coil Relays in a Control Panel(PLC) rated for clss1 div2 area, do the relays have to be class1 div2? Or can they just be Hermetically Sealed?

Are these relays going "in a Control Panel" or are they going in a "(PLC)?

Maybe it is not that clear. I took it to mean as in a control panel that also contains a PLC. And that is probably correct, but to have what you are describing maybe he could have worded it something more like : in a control panel with a PLC that is rated for class 1 division 2. His original wording really seems to be describing the control panel and the PLC as the same thing and we have both taken the meaning to be two different things.

He also said in post #4: "Yes the Control Panel is rated for Class 1 Div 2." further making me believe he has an enclosure rated for CL1 Div2.

 

[weressl]

I quoted the OP earlier, I will quote it again:



Are these relays going "in a Control Panel" or are they going in a "(PLC)?

Maybe it is not that clear. I took it to mean as in a control panel that also contains a PLC. And that is probably correct, but to have what you are describing maybe he could have worded it something more like : in a control panel with a PLC that is rated for class 1 division 2. His original wording really seems to be describing the control panel and the PLC as the same thing and we have both taken the meaning to be two different things.

He also said in post #4: "Yes the Control Panel is rated for Class 1 Div 2." further making me believe he has an enclosure rated for CL1 Div2.

I also took it to mean a control panel that contains a PLC. I also understood that he uses additional external - to the PLC - relays, perhaps to have a higher rated output than the PLC is capable of and the question concerns the listing of those relays.

As I pointed out before, the term 'enclosure rated for Cl. I, Div. 2' is close to meaningless to define what the actual construction of the panel is.

 

[jap]

I took it that he already had an enclosure rated class 1 div 2 with a PLC inside of it and was asking if he added relays inside the enclosure did they have to be hermetically sealed.

So I'll repeat mine too,


If you have an enclosure that is Class 1 Div 2 rated with the proper seals there is no need for hermetically sealed relays.

I'll humor you by saying I work in Class 1 Division 1 areas and most all of the enclosures are explosion proof with sealoffs for every entry with non-hermetically sealed devices inside if them. Engineers design.

Mostly just the light switches are hermetically sealed and dont require sealoffs.

3 of the 4 walls are 8" reinforced concrete and the outside wall is hinged so in case of an explosion the blast blows everything outside
instead of into the plant.

 

[don_resqcapt19]

...
If you have an enclosure that is Class 1 Div 2 rated with the proper seals there is no need for hermetically sealed relays.

I don't think that there is any such enclosure. As far as I know, it you have to use seals, it must be an explosion proof enclosure and it be the same enclosure no matter what division it is in.