These were two critical questions facing Glaxo, Inc., a prominent international pharmaceutical manufacturer, when construction plans were being developed in 1988 for the firm's Venture Center in Research Triangle Park.

The design engineers were faced with maintaining temperatures between 72 and 74F 24 hours a day. Glaxo's research personnel and equipment would be housed here, including delicate animal and chemical experiments. Humidity was a concern, since a moisture imbalance could do costly damage. Another concern was the emission of destructive RFI (radio frequency) and EMI (electro-magnetic) interference.

Moreover, the entire job had to be specified, designed and built in about six months, where a project like this normally requires a year or more.

To meet these challenges, design engineers from Glaxo and O'Brien Atkins, P.A., a Durham-based consulting engineering firm, could have gone with the conventional solution: Install constant speed pumps and regulate the flow through the building distribution loop using two-way valves. This is a proven solution with a lower initial investment than some other options.

However, a constant speed pump doesn't maintain high efficiencies under varying operating conditions. The pumps would be sized to meet peak demand, and valves would have to be throttled for the pumps to work close to actual block load design, which would occur the majority of the time.

Early projections indicated that pumping chilled water throughout the Venture Center was going to require two 75-horsepower pumps capable of 2400 GPM at 90 feet TDH and 1750 RPM. The yearly cost of operating both constant speed pumps in parallel and staging to a single pump under low load conditions was calculated at $46,034.

The design engineers opted for a more effective solution. Working closely with the Packaged Systems Group of Bell & Gossett (B&G), a Chicago area subsidiary of ITT Fluid Technology Corp., they quickly determined that the superior option was a PowerSavô Variable Speed Pumping System.

Running both of the 2400 GPM variable speed pumps in parallel and operating only one of the pumps to carry the load when demand was light (while automatically staging on the other as load increased) would cost only $17,461 a year. The savings, $28,573 a year, would pay for the variable speed pumps in less than two years.

Four differential pressure sensor/transmitters were installed around the Glaxo distribution loop. Set points for each are adjusted individually. Additional sensor/transmitters can be installed in the future, if necessary.

The B&G Technologic 3000 Pump controller can be used to monitor up to 15 zones throughout the laboratory building and adjust the pump speed to match actual system demand.

based on specific compliance requirements, Glaxo chose B&G's variable voltage inverter (VVI) adjustable frequency drive (AFD). The VVI/AFD is a logical choice for a laboratory installation because it can meet IEEE 519-1981 and FCC Para 15 subpart J RFI/EMI noise and interference standards without a need for costly and inefficient filters or isolation transformers.

Standard equipment on the VVI drive includes fault detection/trip circuits, manual speed control, indicating meters, status lights, alarm lights, ground fault protection, elapsed time meters and H-O-A switches.

Bell & Gossett was chosen as the pump systems supplier for this rush job. B&G stood ready to deliver a complete system (pumps, pump controllers, adjustable frequency drives and sensor/transmitters) within the required schedule. And the company would take complete unit responsibility for the system, a single source for ordering, delivery, operation and any questions regarding system components or the system as a whole.