Commercial Architecture April 2018 - 40

PROJECT

hvac
that it is not over pressurizing the system components downstream
of the pump," Buscher said. Even at shutoff, the static pressure in the
turbine pumps was 77 psi, which required a pressure-reducing valve
on the standpipe systems. "Controlling the pressure was our biggest
challenge," Callahan said.
The Wilshire Grand fire-protection system design is also unique
in the low-zone pump room, with the vertical turbines sitting atop a
120,000-gal. three-story water tank in the second of five basement
levels-with space at a premium on the site, there was no room for it
outside the building. Designers had to be sure this setup would meet
the NFPA 20 requirement on how tanks are constructed and that the
fire pump would be capable of providing demand for the whole
building in an emergency.
BEYOND THE BUILD

In a project the size and scope of the Wilshire Grand Center, adhering to the timeline is vital to the project's success. The construction
site posed additional challenges-at just 2.8 acres, the site offered no
space to store materials.
"A 73-story building takes years to build, so project coordination
in regard to product lead times and deliveries had to be in line with
the construction schedule," Masso said. "Deliveries were lifted by
cranes to the floors when they were needed."
Once HVAC and fire-protection systems were in place, the next
steps were to test the systems and train building personnel on their
operation. On the fire-protection side, the fire-pump acceptance test
was an essential step in obtaining the occupancy permit for the
building. In testing the equipment, there was some fine-tuning in the
time between turning on the pump and it feeding into the split-case
pump. By adjusting sequencing with the fire-pump controller, the
team was able to close the gap from 10 to 15 sec. at startup to just 7
sec. The system also met the challenge of the 600-psi requirement.
"In the end, everything worked as designed," Callahan said. "It's
not just putting in products; everything had to perform properly as a
system and meet code."
On the HVAC side, Dawson Co. representatives conducted
equipment training for maintenance and other personnel on the 18
Bell & Gossett products prior to the building opening.
With nearly two-dozen skyscrapers being built in the City of Los
Angeles, the Wilshire Grand Center likely won't be the tallest building in L.A. for long. However, from its roots as a pinnacle of modern
design, it stands tall as a symbol of the new way of thinking about
L.A.'s traditionally flat-roofed skyscrap-

there was no need for an additional emergency generator, saving proj-

commercial building, using an integrated-design approach involving

ers are required to have helipads by city
code, but the Wilshire Grand architects
obtained an exemption reportedly because of the addition of other fire-safety
features that would exceed the city's firecode requirements. Photo: Gary Leonard/
Wilshire Grand Center

ect cost," Callahan explained.

the fields of architecture, engineering, and construction to achieve

Once the design was conceived, the team had to be sure the sysretical planning on what the pump curves would look like, especially
in the high zone where the vertical turbines pump into the split-case
pumps and were approaching 600 psi," Bennett said.
That also becomes more complicated because of NFPA 20 requirements for fire-pump impellers, which state the pressure at shutoff cannot exceed 140% of the rated pressure at the rated flow and
can't be below 65% at 150% of the rated flow.
"One of the things we look at is not just the design-point flow and
head-system needs, but also what the pressure is on the pump when
it is at churn. We have to design the impeller to limit that pressure so

COMMERCI A L A RCHI T EC T URE

APRIL 2018

safety, efficiency, and sustainability goals. CA

tem would work as planned. "We had to do a lot of sizing and theo-

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Table of Contents for the Digital Edition of Commercial Architecture April 2018