Case study 1
Rotovaps: It used to be common to see
rotovaps out on the lab bench, but over the
last 10 years these devices have moved into
the fume hood due to the evaporation of
solvents. Because rotovaps require space
for the instrument as well as work space for
other hood-related operations, the hoods
tend to be extra deep, eight feet long and
use 1,090CFM at 100 fpm. This configuration burns $6,867 in energy (based on 6.30
per CFM) each year.
In this example, the lab user requested
four eight-foot hoods. During the initial
stages of the design process, it was discovered that the real reason for the large
hoods was the lab user planned to place
a rotovap in each hood. Two options,
including energy costs, were presented to
the user groups (see Table 1).
TABLE 1
Working with all project stakeholders, a
design solution of four ventilated enclosures
with four smaller hoods was delivered. This
saved the lab user 840cfm and $5,040 per
year in energy costs, provided a safe work
environment (including dedicated hood
space) and lowered the operating costs of
the lab space. An additional solution of
a reduced face velocity on the ventilated
enclosures in both occupied and unoccupied
modes was presented; but due to the high
toxicity of compounds, the health and safety
group advised staying in a constant volume
operating mode under all conditions.
Case study 2
Biochemistry Lab: This example demonstrates an approach for larger, more complicated labs, such as a 4,000 sf biochemistry lab that works with toxic compounds
and a fixed quantity of HEPA filtered
exhaust. The users’ initial request had 22
capture devices, including 16 six-foot fume
hoods. The existing exhaust system was
designed to support a one fume hood per
lab module ( 11’ 6” wide by 26’ lab zone).
Using the same inclusive design process, all
the key stakeholders were involved, including
the user group, facilities, health and safety
and design teams. The health and safety
team and an outside organization conducted
an in-depth risk analysis to evaluate all the
products used and processes performed in
the lab. They provided a report which band-
ed all the processes and identified where an
enclosure would be required and the type of
enclosure that should be used. An example
of the evaluation table used to determine risk
can be found in Table 2.
TABLE 2
This report was used to recommend
exhaust options. The initial request of 16
fume hoods was reduced to four, combined
with two glove boxes, three equipment connections and 16 ventilated enclosures. The
user group was provided with four more
enclosures and the CFM usage was reduced
by 5,145 cfm to deliver an energy savings of
$6,760.97 per year (see Table 3).
TABLE 3
By working with all the stakeholders, a
safe solution for the researchers was developed. At the end of the process the project-ed energy savings when compared to variable volume fume hood was minor, but the
maximum total exhaust was within existing fan and filter limitations. This solution
included developing standard operating
procedures (SOPs) for each process in the
lab prior to the construction of the lab,
thereby reducing operational costs.
SELECTION PROCESS
The best practices for lab design
include the process of identifying the
right capture device in the initial pro-
gramming phase. Here is a
three-step process to help
determine the right device for
a lab:
1. Involve all the stakeholders
and an industrial hygienist.
2. Describe the hazardous
procedures using the primary
characteristics to quantify
these procedures including:
variable exhaust air strategies (not
occupied in front of containment device,
process not active or standby with con-
tainment device, sash or containment
device door closed).
3. Select the best device and air management strategy for the task based on the
information gathered.
Once there is an understanding of what
device is necessary, it’s time to review
proper installation and testing of the
selected device to validate that it is performing as described in the specifications.
After ASHRAE/ANSI 110 testing is completed, it is important to train each person
who uses the capture devices to ensure the
devices will operate as designed. While
safety is the most important goal of the
containment device, it is critical for users
to be are trained to understand how a
simple procedure, such as closing a sash
or door opening, even when the device is
not in use, will save energy and possibly
provide additional operational funds for
new research.
Type -Size
CFM
Energy
Option 1 4 4360 $27,467.70
Option 2 4 4 3520 $22,175.76
Savings: 840 $5,291.94
Type -Size
CFM
Energy
Cost FH-72 RVE VE-36 VE-48 VE-60 VE-72 GB-35 GB-72 Ex-LYO Ex-utl Ex-ms
Option1 16 4 0 0 0 0 1 1 1 1 1 14,930$68,405.79
Option2 4 4 3 2 5 6 1 1 1 1 1 9,785 $61,644.82
Savings: 5,145 $6,760.97
Ref
No.
Group Contact Task
Name
2nd Tier
Task
Lab Task Material Location Risk
Level
Enclosure
Required
x- 1 Research Joe B. Purifi-
cation
Sample
Prep
123 Weigh-
ing
Powder Open
Bench
RL4 VBSE
continued on page 20
Vented equipment enclosures. Image: Courtesy of BHDP