diameter. Where maintenance access is required, piping shall be
installed in accessible locations in covered trenches, tunnels, or
crawlspaces. Provide cleanout fittings at every change of direction
greater than 45 degrees. Minimum access space shall be two feet minimum
to within two feet of the cleanout and a minimum 0.5 foot from this point
to the cleanout. Specify DWV fittings to facilitate movement of solids.
Enlarging the pipe size shall be considered depending upon availability
of the DWV fittings and relative pipe costs. When overhead pipe routing
cannot be practicably avoided, provide cleanout fittings at the base of
all risers and observe the following requirements:
a. Minimize lift height by locating overhead
horizontal pipe run as close to floor as possible.
b. Vertical pipe run from inlet to overhead pipe shall
be a minimum 40-millimeter (1-inch) diameter.
c. Overhead pipe shall be not less than 40 millimeter
(1 inch) minimum in diameter.
d. The vertical pipe shall "tee" into the top of the
overhead branch main.
e. The available vacuum level to satisfy performance
requirements stated in 220.127.116.11 shall be based on a
reduction of the pump-generated vacuum at the rate of 3
kPa (1 in-Hg) for each 0.33 meter (1.1 foot) rise.
connection to the equipment discharge point, shall be in accordance with
manufacturer's recommendation. The number of bends and total length
shall be minimized. The exhaust piping shall be a dedicated run from the
equipment connection to the discharge point outside the MTF. It shall
not be connected to any other piping, such as a plumbing vent line. The
exhaust line shall be protected from backflow of air or liquids by
detailing an appropriate discharge arrangement, such as a gooseneck or
shroud with screen with a check valve, or using a flapper valve approved
by the manufacturer. The discharge point shall be separated a minimum of
10 meters from the dental or medical compressed air system intakes and
any HVAC system outdoor air intake(s).
Central Dental High-Volume Laboratory Dust Evacuation (LDE).
The LDE system shall scavenge and centrally separate, filter, and collect
material trimmings, grinding debris (toxic and nontoxic), and
laboratory. Point of use dust collection may be provided for some
operations per using Military Department requirements.
System Components. The LDE system for dental laboratories
shall consist primarily of one belt-driven vacuum pump complete with a
preset, field-adjustable ingestion valve, exhaust silencer, and a central
cyclonic separator with a filter bag system.
Performance. A vacuum of 10 kPa (3 in-Hg) shall be
maintained at the separator. The vacuum at the farthest inlet shall be a
minimum of 4.2 kPa (1.25 in-Hg). A flow rate of 28 L/s (60 scfm) per
technician work station inlet and 71 L/s (150 scfm) per equipment item
inlet shall be measured while maintaining the 10 kPa (3 in-Hg) at the
separator. Verify the equipment requirements with the using Military
Demand. The system demand shall be calculated based on the
inlet flow rate requirement. Apply the usage factor values shown in
Table 9-12 for the given number of inlets.