Consulting-Specifying Engineer - October 2008 - (Page 22)

M/E Roundtable tive). If the offset has been undersized due to excessively leaky construction, exhaust capacity may fall short. The same holds true for the reverse—tight room, oversized. We frequently see situations where fans are running at a design static pressure higher than design in order to meet flow requirements. Maintaining pressurization during steadystate is challenging but usually accomplished for most facilities when all is said and done. The harder part is addressing the unfortunate, but undeniable, realities of power failures, return from power failures, partial power outages, equipment failures, etc. All of these situations need to be addressed and incorporated into the design. How to operate during fan degrade mode (that is, fan systems—supply or exhaust— not running at effective capacities). Brooks: Lab ventilation systems, as well as all fan systems, require well-designed components used within well-designed systems. A high-efficiency fan that is not properly selected or placed in a poorly designed system may not perform as desired. The system has to be designed to eliminate system effects. The days of procuring oversized fans to account for system uncertainties are (or should be) over. The system designer should be familiar with system effects in order to avoid them. Designers may have nightmares about procuring equipment that does not deliver on performance promises. Ensuring the equipment is certified by independent third-party organizations, such as AMCA International, can help allay that feeling. CSE: What tricks and tips would you give lab designers for specifying systems and equipment that will help improve performance in the field? Tsimanis: There are many items that are critical in the laboratory design process. System flexibility, serviceability, and controllability are several elements that are essential for the system’s performance success. The lab control system needs a fast response and a reliable control interface capable of providing a safe environment within the laboratory spaces. It is suggested that in the design phase of the project, the airflows in each space are carefully defined with allowance of the air infiltration and exfiltration from each space. Hanegan: The best advice I have for specifying systems and equipment is to enforce the specification requirements. This means obtaining owner buy-in that the specifications will be enforced with the contractor (since the buck stops with the owner), writing a spec that is complete and has properly edited boilerplate, and being thorough in site observations. The benefit is that the owner gets what he pays for and the design performs as intended. It also provides an honest, level playing field among contractors and equipment suppliers. Input #213 at csemag.com/quickResponse 22 Consulting-Specifying Engineer • OCTOBER 2008 http://www.uecorp.com http://www.uecorp.com http://www.csemag.com/quickResponse

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Consulting-Specifying Engineer - October 2008 Contents Viewpoint Letters News M/E Roundtable Cities Under One Roof Eight Design Tips for Integration Is 'Green' Really New? Down the Drain Product of the Year Awards Codes & Standards Case Study New Products Equipment Lifecycles Advertiser Index Green Space

Consulting-Specifying Engineer - October 2008

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