EXHAUST GAS SCRUBBERS
Scrubbers shall be designed for specified collection-removal efficiency of air contaminants arising from the processes listed herein. Collection efficiencies shall apply to the unit as a whole, including mist eliminators downstream of the packing. Overall mass collection efficiency shall be ___% or better at design gas flow.

The collection efficiencies shall be achieved with a scrubbing solution waste flow rate of not more than 0.7 gallons per minute per thousand (1,000) cubic feet per minute of gas flow, and pressure drop across the entire scrubber unit including the mist eliminator of not more than 2.5 inches water column.

Corrosion Resistance:

1. Scrubbers, including all internals and appurtenances, shall be completely resistant to chemical corrosion from the process chemicals listed herein and shall carry a warranty against corrosion-induced failure for one year after initial start-up.
2. Scrubber housings shall be constructed of Type ll, Grade 1, high-impact polyvinyl chloride (PVC)* conforming to ASTM D 1784-69 Cell 1433D. Outdoor installation shall be white PVC for UV resistance.

Base: Each scrubber shall be complete with a corrosion resistant coated steel base of sufficient strength to make the unit self-supporting when wet.

Scrubber Piping:

1. Furnish all scrubber internal piping necessary for recirculation of scrubbing solution such that installer need only make single external piping connections for scrubbing solution supply and return. Piping shall be polyvinyl chloride (PVC)*. Wherever possible, piping shall be installed at the factory. Interior piping to be removable through access doors for maintenance.
2. Spray nozzles shall be full cone non-clogging type of sufficient quantity to insure complete coverage of the packing face. On horizontal scrubbers, overhead spray headers shall be provided to prevent channeling of the
   gas stream.

Pumps: Recirculation pumps shall be vertical sealless centrifugal chemical duty type, constructed of materials completely resistant to corrosion from all contaminants listed herein. Pump motors shall be single-speed, NEMA Design B, Class-B insulated, 230/460 volts, 3-phase, 60-hertz. All external pump and drive components shall be of corrosion-resistant construction or otherwise epoxy- coated. Pumps shall be

securely mounted to sump box or remote tank. Pumps shall be sized to handle a minimum of 40 TDH on self-contained and 70 TDH on remote recirculation systems.

Remote Recirculation Tanks: If required, each scrubber will be furnished with a remote recirculation tank to be constructed of PVC*. Fittings will be provided on the tank for pump suction, overflow, and drain. Tanks shall be of sufficient capacity and structural rigidity for intended service. Tank freeboard above the overflow connection shall be of sufficient volume to contain liquid volume suspended in supply and return pipes and scrubbers. Recirculation pumps shall be mounted on top of tank. Pipe and fittings necessary for connection of pump suction to tank will be furnished.

Scrubber Packing: The scrubber packing shall be resistant to corrosion from all contaminants listed herein. Packing shall be non-clogging, non-nesting and of such design and bed depth as to achieve certified collection efficiencies stated herein. Minimum void volume of packing to be 93%.

Mist Eliminator: A mist eliminator shall be provided to effectively remove entrained water droplets prior to leaving the scrubber.

Access Panels: Removable access panels for packing removal and spray nozzle maintenance shall be furnished. Transparent view ports to allow for inspection of packing and spray nozzles are also standard.

Flow Meter: A flow meter for indicating/adjusting fresh-water make-up will be furnished. Dwyer instruments Series RM that clearly indicates design flow on scale will be utilized.

Pressure Gauge: All Duall fume scrubbers are supplied with a pressure gauge to monitor pressure differential across the filter packing. The Duall specified gauge would be a Dwyer instruments Series 2000 Magnehelic, or equal.

OPTIONAL CONTROL PACKAGES
Chemical Addition Control Package: The Duall chemical addition control system consists of a weathertight, corrosionproof enclosure containing an analyzer, prewired chemical feed pump and weather-protected terminal block. Enclosure can be mounted on any vertical surface. A heavy-duty industrial probe with a 10-ft. lead wire is supplied, along with two 10-ft. lengths of vinyl tubing to connect the feed pump.

Motor Control Package: A motor starter panel with fused disconnect is available for start-stop motor control. Standard panel includes fan and recirculation pump control, based on 460 volt / 3 Ph / 60 Hz. power supply.