I have a new mix room classified as C1D2. All of the instruments (level switches, massmeters, solenoid valves, pressure transmitters) within the room are rated for C1D2. The I/O for these instruments will be wired using rigid conduit and sealtite (at instruments). The I/O wiring will be routed to a NEMA 4X enclosure located in the room which will house remote I/O modules rated for C1D2. All local wiring within the room. From the NEMA 4X enclosure, the remote I/O network (Belden cable) will be routed using rigid conduit to a non-hazardous area enclosure which will house the PLC. I was planning on providing conduit seals prior to entering the mix room (passing from non-hazardous to C1D2). Do I need conduit seals for each instrument inside the room (local wiring)?
C1D2 Conduit Seals
- Thread starter jesterd
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- Mission Viejo, CA
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- Professional Electrical Engineer
For the level switches - probably. For the meters, solenoids and transmitters ? probably not. However, no one can tell you this with certainty without having specific details of the instruments.jesterd said:
The solenoid valve is an ASCO explosion proof 24VDC valve used to open and close the process valve. The limit switches are explosion proof, 24VDC and are part of switch package to indicate valve position. Both the solenoid and limit switch package are integrally mounted to the ITT diaphragm valve. This is typical for all process valves in the room. Should ITT tell me whether a seal-off is required?
The massmeter and pressure transducers are Rosemount sensors. Specifications for both sensors list that the instrument is rated for C1D2. Should Rosemount tell me whether a seal-off is required?
The massmeter and pressure transducers are Rosemount sensors. Specifications for both sensors list that the instrument is rated for C1D2. Should Rosemount tell me whether a seal-off is required?
petersonra
Senior Member
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- Northern illinois
- Occupation
- engineer
jesterd said:
None of these manufacturers have any code making authority, nor do they interpret the code.
I don't want to simplify this too much but generally only devices likely to create an arc are required to have XP enclosures in a C1D2 area, and only those items that require XP enclosures are required to have seals.
Since you said the valve limit switches are 24VDC, it seems possible they are solid state switches, is so they are probably not an arc producing device.
You can put stuff in a C1D2 area in an XP housing that is not required to be XP, but there is generally not a requirement to seal it just because it is an XP enclosure, only if it is required to be XP.
Take a close look at the requirements in article 501. There are only a few sections you need to worry about when wiring inside this area.
YMMV.
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petersonra, I agree with you. Let me provide a few more details.
The ASCO solenoid valve nameplate; "For use in hazardous locations Cl.1 Div.1, Gr. A,B,C & D; Cl.2 Div.1, Gr. E, F & G."
The ITT valve positioner nameplate; "Valve position monitor for use in hazardous locations NEMA Type 4, 4X, 7 & 9 Class 1, Groups B, C & D. Class II, Groups E, F & G Division 1 & 2.
This is the specifications from the manufacturers. As mentioned in the original thread, would these two require seal-off in my C1D2 mix room?
The ASCO solenoid valve nameplate; "For use in hazardous locations Cl.1 Div.1, Gr. A,B,C & D; Cl.2 Div.1, Gr. E, F & G."
The ITT valve positioner nameplate; "Valve position monitor for use in hazardous locations NEMA Type 4, 4X, 7 & 9 Class 1, Groups B, C & D. Class II, Groups E, F & G Division 1 & 2.
This is the specifications from the manufacturers. As mentioned in the original thread, would these two require seal-off in my C1D2 mix room?
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
jesterd said:
Solenoid valves are called out as not requiring XP enclosures in the code when used in a C1D2 area, so IMO the answer is that the solenoid valves require no seal off since an XP housing is not required.
The valve limit switches, IMO, require a seal IF they are a mechanical switch which can produce an arc when it opens. If it is a solid state switch, I would say no seal required.
- Location
- Illinois
- Occupation
- retired electrician
The issue of seals is why we specify magnetic reed switches in all of our valve position switches. It seems that with most suppliers if you tell them that the valve is going in a Class l, Division 2 location, they will provide an explosionproof enclosure with mechanical switches requiring the use of a seal, and costing more than the NEMA 4 enclosure with magnetic reed switches that does not require the use of a seal.
Don
Don
Natfuelbilll
Senior Member
I understand that devices which normally require a seal can be sealed at the factory and are then specifically labled "Factory Sealed", and if it not labled, it is not factory sealed.
- Location
- Illinois
- Occupation
- retired electrician
Natfuelbilll,
Don
The magnetic reed switches that I use are hermetically sealed and are not marked or labled as "factory sealed".
Don
Natfuelbilll
Senior Member
For boudary seals (C1D2 to non-hazaedous) I believe that I saw a note that the sealing compound is not required to be the explosion proof type, but something suitable for eliminating transmission of gases (silicone?)
The factry seal feature would be for use on a device (eg: disc. switch) which is required to be XP sealed. I believe the hermetic reed switch need not be sealed. right?
The factry seal feature would be for use on a device (eg: disc. switch) which is required to be XP sealed. I believe the hermetic reed switch need not be sealed. right?
- Location
- Illinois
- Occupation
- retired electrician
Correct, but since it is not sealed in the field it is often refered to as "factory sealed".
Don
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