Engineering systems in manufacturing, industrial buildings: Building automation and controls
Manufacturing and industrial facilities require specialized building automation, monitoring, and control systems.
Jonathan Eisenberg, PE, Associate Manager, Rolf Jensen & Associates Inc., Boston
Brian P. Martin, PE, PDX Electrical Discipline Manager, CH2M Hill, Portland, Ore.
Peter Pobjoy, PE, LEED AP, Chief Design Officer, Southland Industries, Los Angeles
Peter Zak, PE, Principal, GRAEF USA, Milwaukee
CSE: When designing building monitoring and control systems, what factors do you consider?
Eisenberg: We often recommend fire protection features, such as explosion control, that include gas/vapor detection and monitoring. Design and location of these systems depends on the properties of the liquids and gases that are present. Important questions like high or low placement of the detectors need to be answered. For an outdoor process installation, a flame detection system has to “see” all angles of the equipment in order to perform correctly.
Zak: Several things we evaluate when designing a control system are:
- Owner operating level of expertise
- What is the complexity of the system, and to what level should it be monitored?
- Does the owner want the ability to change control points?
- Is energy consumption being tracked?
Pobjoy: These include:
- Keeping the level of complexity to a minimum and understanding how the facility will be operated and by whom
- Infrastructure approach—distributed versus centralized
- Digital versus hardwired
- Commercial level or industrial level controllers (such as programmable logic controllers, PLCs)
- Redundancy—are the controls required to be backed up in certain areas or on certain systems?
- Calibration—do the control devices need to be calibrated in the field?
- Accuracy—do the processes require tight tolerances for temperature and humidity?
- Quality of valve and damper actuators.
CSE: What are some common problems you encounter when working on such systems?
Zak: The most common problem is the interface between multiple control manufacturers; a good example would be to integrate the building automation system (BAS) with the control or alarm panel of a manufacturing process device. While some points could be monitored, total control/monitoring is not practical due to interface costs and in most cases machinery manufacturers’ warranties that exclude control by any other software other than what is provided. This can create difficulties if you are using part of the process waste energy for environmental heating or cooling.
Pobjoy: Those include commissioning of complex controls systems and response time between input signal and end device functionality.
Eisenberg: Many of the hazardous materials detection and control systems are designed well, but there is not enough discussion about the appropriate response by the facility and local emergency agencies in an alarm condition. The design should incorporate approaches for questions such as: Who is notified of an alarm? Does the fire department respond? Who meets the fire department and has knowledge of the alarm’s origin? Does the entire facility evacuate when an alarm and control interlock is activated?
CSE: When integrating systems (HVAC, electrical, fire protection, etc.), what challenges must you overcome?
Zak: Defining the limitation of each discipline specific control system, another challenge is how to coordinate communication protocols while requiring open competitive bidding.
Eisenberg: One interesting condition on several recent projects occurred in bulk chemical (Group H, High Hazard) rooms. It was clear that the exhaust needed to be on emergency power, but there was not as much discussion of the supply air. If we wanted the organic vapor detection in these rooms to automatically ramp up the rate of air change to a “purge” mode, we need to verify that at least a portion of the supply air is also on e-power. In this way, there is always an air change and the occupants can egress without door opening issues caused by 100% negative exhaust.
Pobjoy: Among those challenges: Protocols of the different manufacturers as well as a very good supervisory control and data acquisition (SCADA) system or front end.