MIL-HDBK-1191
Dental Low Vacuum (DLV). A central low vacuum, high volume
9.6.17
oral evacuation system or DLV shall be installed in dental clinics to
provide scavenging, collection, and disposal of liquids, solids, and
aerosols from dental procedures. This is a wet system with liquids and
solids transported through wetted piping from the collection point to
one or more liquid/air separator tanks located upstream of two or more
vacuum pumps. The tank serves as a collector for the fluids and solids
and provides a means of automatic draining for them by being connected,
indirectly, to the sanitary sewer. The tank draining system may include
an automatic wash down feature for larger systems in an MTF having
greater than 10 DTR's. The system shall meet the requirements of NFPA 99
(reference 9r) Level 3 vacuum systems. The vacuum pumps shall be sized
so that when one pump is inoperable, the remaining pump(s) shall provide
the above vacuum pressure and fluid flow for a minimum of 70% of the
system demand. The system design shall include automatic operation of
the vacuum pumps including alternating lead/lag status. Provide an alarm
to indicate vacuum system fault (e.g. pump failure) that annunciates to
the master medical gas alarm panel. Protocol shall include alarm
initiation when a pump does not operate when called for and when a pump
operates when not called for.
Components. The service inlet normally is floor mounted in a
9.6.17.1
utility center at the dental chair, or wall mounted with a means of
connection to clinical end items such as the high volume hose. The
separator(s) shall receive all liquid, air, and solids upstream of vacuum
pump(s). Liquids and solids shall be discharged from the separator(s),
with piped gravity flow through an air gap into a trapped and vented
receptor (e.g. a floor drain or sink, or standpipe receptor for small
system suspended tank installations) connected to the sanitary waste
system. Local codes may require the use of an amalgam separator between
the separator tank and the sanitary waste system to control the discharge
of mercury into it. Refer to 9.2.7.8 for additional guidance.
Coordinate with the Installation or local regulatory agency when
discharge is to a public sanitary system. For government operated
systems, coordinate with the using Military Department or the
Installation. The separator tank shall discharge a minimum of once
during a 24-hour interval for a one-tank system, when a high liquid level
sensor activates for a two-tank system, or multiple daily discharges as
recommended by the manufacturer.
Separator overflow protection shall be
included to protect during periods of abnormal usage or when the
automatic discharge malfunctions.
Performance. The system operating range shall be 21 to 27
9.6.17.2
kPa (6 to 8 in-Hg). A minimum vacuum of 21 kPa (6 in-Hg) shall be
maintained at the farthest inlet. System pressure drop shall be a
maximum of 3 kPa (1 in-Hg) at the calculated demand flow rate. A flow
rate of 3.3 L/s (7 scfm) per inlet shall be measured while maintaining 21
kPa (6 in-Hg) at the farthest inlet.
Demand. The system demand shall be calculated based on 3.3
9.6.17.3
L/s (7 scfm) per inlet-nozzle orifice. To offset piping and component
losses, increase the demand flow rate by the appropriate factor from
Table 9-10.
9-25
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