bottom drain. With negative pressure in the tank, the check valve shall
remain closed to maintain vacuum. When negative pressure ceases, either by
vacuum producer shutdown or by closure of the outgoing air solenoid control
by the liquid level sensor, the check valve shall open and the tank shall
undergo gravity drain.
2.22.1.7
Piping
Vacuum pipes shall be of corrosion-resistant material, shall have a smooth
internal surface, and shall not collapse when installed in an HVE system
evacuated to 41 kPa 12 inch Hg gauge. Piping shall be cut square, with
burrs removed, and installed with minimum obstruction to airflow. Vacuum
pipe shall be acrylonitrile-butadiene-styrene (ABS) conforming to ASTM D
1527 or polyvinyl chloride (PVC) conforming to ASTM D 1785. Solvent cement
for ABS plastic pipe fittings shall conform to ASTM D 2235. PVC plastic
pipe fittings shall conform to ASTM D 2466, and solvent cement shall
conform to ASTM D 2564 (DWV fittings for vacuum piping shall conform to
ASTM F 1866). Fittings, supports, and joint assembly shall comply with ICC
IPC. The assembled piping system shall be suitable for [_____] kPa inch Hg
vacuum service. Fittings shall be the long-radius type for turns and the
wye type for branches. Vacuum piping shall slope not less than 10.0 mm per
meter 0.12 inch/foot to the separator tanks. The most distant end of each
trunk line from the separators shall terminate with a vacuum relief valve.
Couplings, unions, and other disconnecting couplings shall be readily
accessible at all times. Discharge piping from the vacuum producers shall
be galvanized steel tubing with a minimum wall thickness of 1.994 mm 14
gauge.
2.22.1.8
Vacuum Relief Valve
The vacuum relief valve shall be mechanically operated. The valve shall
operate automatically at [_____] kPa inch Hg vacuum and shall be adjustable
between [_____] and [_____] kPa [_____] and [_____] inch Hg vacuum. The
vacuum relief valve connector shall be 15 mm 0.5 inch NPT. The valve shall
be equipped with a silencer to attenuate air noise to 85 dB.
2.22.1.9
Spare Parts
A turbo-exhauster bearing and coupling kit shall be furnished with the
delivered system and shall consist of one set of exhauster bearings and one
complete motor/exhauster flexible coupling, all of the same size and design
as those supplied with the turbo-exhauster. The kit shall also include
complete installation instructions for repair kit items.
2.22.2
High-Volume Evacuation System (HVEL)
The central HVEL system shall be composed of standard manufactured
products, complete with devices normally furnished and devices required
herein. The central HVEL system shall be supplied by an established
manufacturer of commercially available industrial quality vacuum. The HVEL
shall be a dry system for collection of dust and grinding particulates.
The system shall consist of one vacuum turbine, except for area laboratory
(ADL) application, and a dry, cyclonic, filtered separator.
2.22.2.1
Vacuum Producer
Vacuum producer shall be self-governing multistage, centrifugal type and
may be of overhung or outboard design. The vacuum producer shall operate
at a speed not to exceed 2600 rpm. The vacuum producer shall be connected
SECTION 15405A
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