Have a number of MCC buildings (mostly 480V switchgear) that have existing ventilation systems. They are located in a classified area and need to be de-classified. The ventilation systems should be adequate, but need to be monitored. Does anyone one know of someone that makes a monitor system that can be installed to make sure the ventilation is correct and can be monitored (via a switch input to a PLC/ DCS system). and doesn't stop.
Declassify using ventillation
- Thread starter NOStuck
- Start date
- Status
- Location
- Mission Viejo, CA
- Occupation
- Professional Electrical Engineer
That last clause, “and doesn’t stop,” is a killer. With a proper design you can have an exceptionally reliable system, but never a completely perfect one – although it may not need to be.
For the most part, NFPA 496 Chapter 7 and the appropriate Sections relevant to the pressuring “Type” (X or Z) will direct you to a final design. If you are fortunate, and it sounds likely in your case, and Type Z is all that is necessary, then you will have a relatively broad level of choices to accomplish your goal and virtually any reputable control panel fabricator/system integrator will be able to design it for you. (Actually, the reputable folks could handle Type X very well too; it’s just a much bigger pain)
Type Z offers a lot of wiggle-room for short-term failures; Type X demands an immediate system shutdown. Type Y is not applicable since the Switchgear/MCCs need to operate in an essentially unclassified environment.
For the most part, NFPA 496 Chapter 7 and the appropriate Sections relevant to the pressuring “Type” (X or Z) will direct you to a final design. If you are fortunate, and it sounds likely in your case, and Type Z is all that is necessary, then you will have a relatively broad level of choices to accomplish your goal and virtually any reputable control panel fabricator/system integrator will be able to design it for you. (Actually, the reputable folks could handle Type X very well too; it’s just a much bigger pain)
Type Z offers a lot of wiggle-room for short-term failures; Type X demands an immediate system shutdown. Type Y is not applicable since the Switchgear/MCCs need to operate in an essentially unclassified environment.
Venting
Venting
" They are located in a classified area and need to be de-classified. The ventilation systems should be adequate, but need to be monitored. "
Usualy the area needs to change 6 times in an hour to reduce the level of classification. It also varies as to the types of gas and size of the room.
"Does anyone one know of someone that makes a monitor system that can be installed to make sure the ventilation is correct and can be monitored (via a switch input to a PLC/ DCS system). and doesn't stop. "
Usualy if you have a monitoring system if the system fails, the electrical is shut off. If the LFL is 20% a warning comes on, the vents go on, LFL 40% it shuts the system down.
This is how the international standards are, although I am in Canada I am not sure what exactly the NEC states.
Venting
" They are located in a classified area and need to be de-classified. The ventilation systems should be adequate, but need to be monitored. "
Usualy the area needs to change 6 times in an hour to reduce the level of classification. It also varies as to the types of gas and size of the room.
"Does anyone one know of someone that makes a monitor system that can be installed to make sure the ventilation is correct and can be monitored (via a switch input to a PLC/ DCS system). and doesn't stop. "
Usualy if you have a monitoring system if the system fails, the electrical is shut off. If the LFL is 20% a warning comes on, the vents go on, LFL 40% it shuts the system down.
This is how the international standards are, although I am in Canada I am not sure what exactly the NEC states.
there are several types of systems available, your engineering department should have contacts for them. we placed several duct detection systems in process facilities in Alaska, and they worked very well, some used a light beam, others used a sample of the air. these were all in mcc rooms, and checked the ventilation air in the duct near the entrance of the duct next to the outside wall.
masterinbama
Senior Member
- Location
- Huntsville Alabama
What is the actual classification of the area surrounding the MCC rooms. In grain storage areas we can get by with filtration and positive pressure, monitored by DP's and ROF's.
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