Lab Exhaust Fan | Mixed Flow Fan Curve Review
Many High Plume Dilution Fans used for Lab Exhaust are mixed flow type fans. The Mixed Flow Fan Curve is different from traditional centrifugal fan curves. For one, it doesn’t have a stall point. It can be completely starved of air and still remain in stable operation. The following is a look at a mixed flow fan curve from Strobic Air.
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There is an array of ECM fans at the 
The ECM array provides not only an energy efficient central fan, but provides redundancy with easy to replace multiple fans. The motors also have a longer life cycle and take up less space than traditional fans. A potential candidate for an ECM array in a large building central air handling systems could be a dedicated outdoor air system (DOAS) with the primary air distribution sized for low pressure drop, and ECM fan powered terminal units as well. A facility with such a system would be capable of turning down the central air system to closely match only what the terminal units need for primary air; even if it’s just one terminal unit calling. The manufacturer of the ECM fans at UMMS;
History: The Whitin Observatory is the home of the Wellesley College Astronomy Department and houses classrooms, astronomy laboratory facilities, the Astronomy Library, and faculty offices. Built in 1900, and enlarged in 1906 and 1966, it was ready for expansion and renovation scheduled for 2009-10.
Unit Controls: The unit was designed with VAV capabilities and programmed for schedules and CO2 sensing. The unit came equipped with damper actuators, freeze protection override on the wheel and VFDs with I/O points factory wired to a terminal strip. The Direct Drive fans and Enthalpy Wheel were also factory wired and designed for quick connect in the field. All other controls were provided by the ATC contractor. The electrical and ATC contractors reconnected the loose power wire ends to the 3 motors and added their sensors and flow stations where needed. They also conveniently located and mounted a unit control panel. The panel provided run and speed signals to VFDs, Enthalpy Wheel control, damper signals, and Hot Water/Chilled Water valve position.
A. 
Vibration is primarily transmitted radially from the direction of rotation. The Tri-Stack mixed flow impeller is oriented so its radial direction is in the horizontal plane and thus transmits minimal vibration downward into the roof. Centrifugal fan arrangements radial component are in the vertical plane, therefore a majority of the vibration is transmitted into the roof.
A. As it stands 
Existing Conditions: Football is a proud tradition in East Boston and funding was raised to replace original and antiquated HVAC equipment in the Stadium. 6800 CFM was going to be required to meet ventilation rates for the offices, locker rooms, showers and other spaces. A boiler upgrade was also part of the project. The mechanical space had a small man entry and an awkward shape. A floor cut of the concrete was agreed on and the engineer tried to select a Packaged Energy Recovery Unit that would fit. The floor access could not be cut large enough to rig a packaged unit and a custom field erect unit was not in the budget. 
The Solution: Engineered Systems, Inc. (ESI) selected a supply and exhaust fan to move the required air. David Goodman from DAC Sales sized and selected a passive Heat Pipe Energy Recovery Module and 5 Hot Water reheat coils, the largest to be located after the Heat Pipe in the mechanical space. The Heat Pipe selected was 120”L X 40”H – 6 Row – 12 FPI. The Heat Pipe, Hot Water Coil and filters were connected to the fans with simple ducting connections. All these parts were chain fall lifted through the new access hole and field assembled according to the plans. 
We routinely use desat coils in laboratory or other critical applications in tandem with heat recovery options. We design these applications with the supply fan in a blow-thru position upstream of the energy recovery device (wheel or heat pipe) to minimize the potential of leakage through the device. In this arrangement, without the supply fan motor heat added downstream of the cooling coil, the desat coil provides an easy way to sensibly raise the leaving air temperature off the cooling coil (usually by 1.5° to 3.0°F).