Basics of HVAC, plumbing systems for industrial, manufacturing facilities
Industrial and manufacturing facilities have specialty HVAC and plumbing needs engineers must include in new or retrofit projects
- Jaimie Ross Handscomb, PEng, Principal, Industrial Buildings, Stantec, Waterloo, Ontario
- Steve J. Sovak, PE, Principal, Salas O’Brien, Chicago
- Jeffrey R. Thomas, PE, CEM, CEA, GBE, CHC, Vice President, Lockwood Andrews & Newnam Inc. (LAN), Houston
Describe a facility in which there were specialty air movement requirements, such as unique air pressure needs or high-velocity low-speed fans.
Steve J. Sovak: In the design of industrial buildings, particularly food processing and pharmaceutical facilities, air movement and pressure relationships are of critical importance. The greatest risk of contamination for a manufacturer of this type is with the incoming raw materials. Keeping them physically separated from the process or finished goods is important, but also controlling air migration is of equal importance. Air migration typically wants to be in the opposite direction as the product flow. Starting at packaging and moving back through various process and cooking stages and back to raw materials the spaces should be increasingly more negative so that the raw storage areas are the most negative and air in the plant migrates back to that location. If this concept is not followed, then there is a risk of contaminants coming in with the raw materials that can move throughout the plant and contaminate work in progress.
Describe an industrial or manufacturing project in which process piping was required. What were the challenges and solutions?
Steve J. Sovak: We have done a number of projects in chemical plants, specifically paint, coatings and resin plants. When working in an existing facility you have to deal with the fact that these production areas are hazardous locations due to the flammable liquids being used in them. Care has to be taken if 3D scanning or even photos are being taken of the existing conditions. Facilities of this type have very strict safety procedures that need to be followed to allow hot work in a hazardous location. Plants are regularly changing out equipment and piping so they need procedures to accommodate activities such as cutting or welding.
How have you worked with HVAC system or equipment design to increase a building’s energy efficiency?
Steve J. Sovak: One recently very popular type of project is cannabis grow facilities. We have been involved in a few and how they are approached varies widely. Something that grows naturally in the wild is such a scientific effort when you bring the process inside a building. Watering rates, time schedules for day and night and allowable variations in temperature and humidity all play an important role in the success of such a project. Being able to control the HVAC system is critical. Changes from high-pressure sodium vapor to LED lighting have a huge impact on system loads and the cost of operation. To optimize the production rates, the system needs to react quickly to the changes in schedule.
What are some of the challenges or issues when designing for water use in such facilities?
Jeffrey R. Thomas: In our experience, water is the easier of the two commodities even for large process plants. Wastewater is the bigger challenge. In our region, for example, water authorities have enough capacity to provide dedicated, large volume, raw water feeds as required. The client simply pays for the connection and consumption. Conversely, we have designed spaces for processes involving (vegetable) cut-rooms and wash down areas where the wastewater streams proved to be much more problematic or costly for the owner. LAN has provided local treatment options for clients to reduce the impact of their process waste and subsequent disposal costs. We have also consulted with municipal wastewater plant operations to expand and improve their processes to better accept and handle the increased demand.
What best practices should be followed to ensure an efficient HVAC system is designed for this kind of building?
Steve J. Sovak: One key to ensuring the right HVAC system is selected for a given manufacturing project is to communicate goals and expectations upfront with the owner at the start of the design phase. This brings to mind a project we did for a drug repack startup company. They would purchase bulk drugs and then repackage them into smaller containers to be used in by mail prescription delivery. Their existing facility was a small makeshift space with standard rooftop air conditioning units. We discussed the space conditions for the new plant and if there was a need to control both temperature and humidity. The plant manager said only temperature control was required.
Sensing this was not the right answer, we sent a letter describing the various HVAC systems that could accommodate both temperature and humidity control. They still went with only temperature control, so the project got built with rooftop units. After less than a month of production, we heard complaints from the quality assurance team that humidity levels were varying all over the map. So, we had to work with the mechanical and controls contractors and the equipment vendor to modify the units to use the heating in a reheat mode. The modifications worked and it was the least expensive fix that could be implemented. But the result was that the manufacturer issued a letter stating their warranties were no longer valid and we got an upset letter from the owner because of this.
What type of specialty piping, plumbing or other systems have you specified recently?
Steve J. Sovak: We just completed design of a small process piping project for industrial coatings manufacturer Akzo Nobel in Waukegan, Ill. This is typical in the industry, but to minimize risks due to hot work in a hazardous environment, we designed the entire product piping system to be stainless steel assembled with sanitary tri-clamp fittings around all pieces of equipment or flanged connections for all elevated pipe runs. This allows the contractor to prefabricate the entire piping system in their shop and then merely assemble the system on-site.
What types of specialty gases or other similar materials have you specified into an industrial or manufacturing facility?
Steve J. Sovak: In some of our heavy industrial projects we are designing provisions for welding systems so it is common for us to be designing storage and piping systems for oxygen, nitrogen, argon, carbon dioxide, etc. We have recently designed two locations, Chicago and Joliet, Ill., for new apprentice training facilities for the Chicago Plumbers Union. Each location had multiple welding booths where up to 20 students could be trained in the art of welding. Each welding booth had a connection through a flexible snorkel to a central dust collection system located outdoors. One thing of particular note is that for the Chicago facility, we were able to secure special permission to recirculate the discharge air from the dust collector back into the building. While this is commonplace in areas bound by the International Mechanical Code, the Chicago Construction Codes specifically states that a dust collector must discharge to the outdoors and that provision was very strictly enforced.
What unique cooling systems have you specified into such projects? Describe a difficult climate in which you designed an HVAC system for an industrial or manufacturing facility.
Steve J. Sovak: Many manufacturing processes require they be done in a constant environment. In the food and beverage, pharmaceutical, electronics and precision machining to name a few, temperature and humidity ranges are vitally important. If ambient conditions are not maintained constant then consistent products cannot be produced. We have designed all types of dehumidification systems, both dry and liquid desiccant, low temperature cooling systems using flooded direct expansion evaporators, ammonia refrigeration systems and carbon dioxide refrigeration systems.
What unusual or infrequently specified products or systems did you use to meet challenging cooling needs?
Steve J. Sovak: In a project for Walgreens, they were trying to achieve a U.S. Green Building Council LEED Platinum, net zero energy building. As a part of the geothermal heating and cooling plant, we researched and specified a carbon dioxide-based heat pump system to serve their reach-in cooler and freezer units. The equipment was manufactured overseas and needed inspection and some modification to achieve a UL label.