Problems with instrument cable voltage drop and DCS cabinet room
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We have a liquid chlorine vaporization project; it’s not a large project, but it is located 500 meters away from the DCS system in the old factory area. I originally planned to place the DCS cabinet room at the boundary of the factory area, treating it as a remote station. According to the farthest gauge, it’s 160 meters, but the original design by the design institute was for our old factory site. After communicating with the design institute, it was stated that current design standards require that the DCS cabinet room must be built as an explosion-proof structure, and the site does not meet this requirement. So it is necessary to go outside the boundary area. So I would like to ask: 1. Is it okay to place the cable in this position? Will there be voltage drop? Or something else. Could you provide a calculation formula? 2. After my calculations, the cost of materials for cable installation will be reduced by 400,000 yuan after the changes. . . However, the vaporization of liquid chlorine is not an explosion zone either. The technology itself is not an explosive device. Is it really required this way? ? ? Thank you to all the experts
Check the range and definition of the explosion-proof area on the general layout, and refer to the relevant petrochemical regulations to determine the distance from the control room. Currently, the management in various chemical industrial parks is very strict. This year, our factory had its control rooms inspected to ensure that the distance between them met the regulations. Our control rooms are not blast-resistant buildings; they are located next to Class A warehouses, and the distance between them is over 45 meters, which meets the requirements.
Since there is no risk of explosion, the cabinet room naturally does not require an explosion-proof structure; it only needs to meet the relevant regulatory requirements.
Further communicate with design institutes, supervisors, etc.
Communicate with the designer; if you can’t reach an agreement, then you’ll have to follow the designer’s requirements. Otherwise, you’ll bear significant responsibility, and in the end you won’t be able to obtain the safety production license without the designer’s approval
This is the anti-riot cabinet room now. . Well, it has nothing to do with whether you’re in an explosion-proof area or not. The purpose of explosion resistance is to ensure that the shock waves and debris generated by an explosion won’t cause damage to your cabinet rooms. An explosion-proof area is a place where explosions can occur; it’s not the same concept. Currently, there aren’t many design firms or organizations that can handle the design of such shock ranges. In our company, all cabinet rooms are designed to be explosion-resistant, even those that are located far away, because there’s no way to prove that they shouldn’t be explosion-resistant. There’s no way around this concept of resisting violence; the standards are set, and it depends on whether you can manage to get by somehow.
If there aren’t many instrument points, can’t we just use a remote field I/O cabinet? Many remote I/O solutions these days can meet the explosion-proof requirements for Zone 2 gases; why go to another cabinet room and be constrained by building codes?
You’re right; many times it’s fine to play it by the rules of ambiguity
On-site IO cabinets are not allowed; the requirements regarding dust protection and temperature cannot be met. . . Moreover, corrosive gases pose a serious problem
I agree with this view. Another common feature of the projects I’ve worked on is that there are no windows on the control room walls facing the equipment
He means that the control room is located far away, and a remote device is used for the dangerous area