Sustainable Vacuum System at Notre Dame

The University of Notre Dame’s new McCourtney Hall of Molecular Science and Engineering is a research facility built around the University’s vision of multi-disciplinary “research neighborhoods,” which would co-locate scientists with overlapping interests.  Completed in 2016, McCourtney Hall is a 219,500 GSF building, with 100,000 ASF of open lab and team spaces.  Some of the lab space would be assigned to faculty who would be relocated from elsewhere on campus, but 40% of the new lab space was reserved as shell space to be built out later when the support needs of recruited faculty were clear.

The university wanted a building in which any type of lab could go on any floor, and in which open labs would encourage interaction as well as providing flexible use of the space. Design firm BSA LifeStructures employed several strategies in order to realize these goals.  Mobile casework with overhead delivery of lab services, along with a mix of central and local utilities. Floor plans were designed with flex space that could be easily allocated to lab or support use, depending on the science requirements. Ductwork for supply air and exhaust was sized and manifolded to maximize the number of fume hoods possible on each floor if needed in the future, for example, to support chemistry or chemical engineering.

As Notre Dame considered its plans for lab vacuum, it had to confront its experience with the central vacuum system in another research building on campus. After aspirated solvents had twice damaged the central pumps, with repair costs each time of about $25,000, the central vacuum there was shut down completely in 2012 after the third instance. Based on the experience elsewhere on campus, it was clear that central vacuum was a nonstarter at McCourtney. The architects for the project had prior experience with local vacuum networks at other institutions, and suggested that Notre Dame consider that technology.

Local vacuum networks are a modular approach for supplying vacuum to lab benches, fume hoods and biosafety cabinets. Instead of a building-wide system, vacuum networks are installed only where vacuum is known to be needed. If the work of a particular lab evolves to require vacuum in the future, it can be installed readily at that time. A small oil-free pump installed in the casework or under the fume hoods and the system is plumbed with chemical-resistant fluoropolymer tubing to connect specially-designed vacuum turrets to the pump. Vacuum is installed lab by lab, so it can scale to the demands of the building, but also be put in later in the spaces reserved for later build-out. Previous experience at Notre Dame indicated that a careless operator in one location could compromise the vacuum supply for the entire building. With local vacuum networks, the vacuum in each lab is isolated from the vacuum in the other labs. This not only protects against the loss of a building-wide utility, it also protects against the scientific risk of cross-contamination between labs through the vacuum lines. As exemplified by Notre Dame’s prior experience with central vacuum systems, service demands and maintenance costs are critical concerns when evaluating vacuum system options.

Upon examination by the spokesmen for the scientists at Notre Dame, the chemistry department head saw the value of the deeper vacuum at the benches and fume hoods. That could potentially eliminate the space demands and equipment costs of lots of dedicated pumps. Both the scientists and facility personnel saw the benefits of a distributed, corrosion resistant system after their prior experience elsewhere on campus. And the fact that the life science labs could have a different vacuum supply that fit their needs while the chemists got what they needed meant that the solution could work for everyone.

It turned out that the installed cost of the local vacuum networks was comparable to the cost of central vacuum, and had the advantage that investment in vacuum supply for the reserved shell space could be deferred until the needs there were clear. Beyond the comparable capital costs and the improved flexibility, the local vacuum approach produces vacuum on demand, so there are material energy savings compared with central vacuum supply. Preliminary measurements of power consumption suggest savings of 55% over a comparable central vacuum system.  In addition to low operating costs, maintenance costs are also low – typical service intervals are 15,000 operating hours, meaning that several years elapse between service stops. Servicing a pump takes about 2 hours.  If back-up supply is needed for critical operations during service, a service pump can be kept in maintenance stock and switched in to replace the installed pumps in about 15 minutes.

All of these advantages supported the university’s decision to rely on the VACUU·LAN® local vacuum networks instead of the traditional fixed vacuum system. Twenty-eight VACUU·LAN® network pumps were installed to provide vacuum at nearly 300 workstations in McCourtney Hall. The pumps create vacuum of 2 Torr – about 29.8 in. Hg – at bench and fume hood ports; this is about 2 orders of magnitude deeper than vacuum typical of central supply. The tubing can be plumbed through ceiling drops with quick-connect fittings, so it was compatible with the flexible layout planned for McCourtney.

Recruitment of the new researchers at Notre Dame has gone well, so that a quarter of the space reserved for new hires was already in the process of build-out within a year of initial occupancy. The modular design approach to the building overall, and the vacuum systems in particular, has enabled the university to quickly fit out this space to the needs of the new principal investigators that have responded to the university’s expanded research initiative.

First seen in PUPN Magazine August 2018 edition.