7-12
October 2012
system, to reduce total water use by an estimated 80 percent.
18
The facility should
consider the impurities gathered within the pump and other characteristics of the
waste being removed when evaluating whether a full recovery and recirculation
system is appropriate. A partial recovery and recirculation system could also be
considered, and the facility could reduce water use by an estimated 50 percent with
its installation. If either recovery and recirculation system option is installed, ensure
that it is properly maintained per manufacturer instructions so that impurities are
removed and hard water deposits do not remain in the system.
If the facility has any other type of vacuum pump that is cooled with single-pass,
non-contact cooling water, a heat exchanger can be added, or it can be connected to
a larger building system chilled water loop or cooling tower water loop. See
Section
6.2:
Single-Pass Cooling
for more information.
Replacement Options
When purchasing a new vacuum pump or replacing older equipment, a non-
lubricated, dry vacuum pump that is air-cooled can eliminate the pump’s water use
altogether. When choosing a vacuum pump, it is important to consider all factors,
including energy and water use. Although they might be more expensive, dry, air-
cooled vacuum pumps can be as much as 25 to 50 percent more energy-efficient
than water-cooled or liquid-ring vacuum pumps.
19
Facilities should note that, in some cases, liquid-ring vacuum pump discharge can
pose a biohazard risk. Therefore, a non-lubricated, dry vacuum pump that is air-
cooled could be the best option. However, if explosive or corrosive gases are being
removed with the vacuum system, the facility might only be able to consider a liquid-
ring vacuum pump. Dental facilities should note that new vacuum systems—wet
or dry, and regardless of the type of cooling system—often need to add amalgam
separators to prevent mercury contamination in water bodies.
20
Savings Potential
Retrofitting existing liquid-ring vacuum pumps with full or partial recovery and
recirculation systems can result in significant water savings, while replacing existing
water-cooled and/or liquid-ring vacuum pumps with air-cooled, dry vacuum pumps
can entirely eliminate water use.
To estimate facility-specific water savings and payback, use the following information.
Vacuum Pump Retrofit
Liquid-ring pumps that utilize water to create a vacuum can be retrofitted to recircu-
late sealing and cooling water rather than discharging to the drain.
7.3
Vacuum Pumps
18
Ibid
.
19
EBMUD,
op. cit
.
20
U.S. Air Force Medical Service,
op. cit
.,
Page 1.
