4.1. System Overview and Basis-of-Design: I. The duplex vacuum pumping system shall consist of two (2) oil-sealed rotary vane vacuum pumps mounted on a single ASME-rated receiver tank with a minimum capacity of 80 gallons, oriented vertically or horizontally II. All performance metrics, including nominal airflow, vacuum, and recovery time, shall be achieved by a single pump in operation. The second pump provide automatic lead/lag alternation for even wear and system redundancy III. The system shall be designed for continuous-duty industrial and municipal applications IV. The system shall include corrosion-resistant construction suitable for outdoor wastewater treatment facility installation V. A factory-wired UL-listed duplex control panel shall be provided VI. Single-Pump Performance Targets: Airflow of 30 CFM at 20 inHgA absolute vacuum Recovery from worst-case drawdown (30 CFM for 20 minutes) to operating vacuum within 120 seconds VII. Bidders may propose alternate pump horsepower (minimum 2 HP) or receiver volume, provided they submit manufacturer performance curves and recovery calculations, including manufacturer test data, demonstrating compliance with single-pump performance metrics 4.2. Vacuum Pump Assembly: I. Pump Type & Configuration: Two (2) oil-lubricated rotary vane vacuum pumps Direct-drive motor with heavy-duty flexible coupling Low-vibration, continuous-duty design II. Performance Requirements: Pump operating speed: 1750 RPM at 60 Hz Nominal vacuum capacity: 30 CFM at 20 inHgA with a single pump running. Bidder shall provide manufacturer’s performance curve showing airflow vs vacuum Maximum attainable vacuum as specified by the manufacturer under ideal conditions Recovery from drawdown: Single pump shall recover from a 30 CFM × 20-minute drawdown to operating vacuum within 120 seconds. Bidder-provided calculations or manufacturer test data required III. Electric Motors: Two (2) 2 HP minimum TEFC motors, 460V, 3-Phase, 60 Hz Dual high-temperature shutdown (internal pump & motor winding protection) Corrosion-resistant motor coating and sealed bearings for outdoor installation IV. Included Pump Features: Inlet check valves (vacuum-rated). 10-micron inlet air filters Inlet isolation valves (weather-rated) Oil/fluid level sight glasses Pump drain valves Discharge pressure gauges Auto-unload valve assemblies with silencers. Discharge check valves Discharge flexible connectors (UV-rated) High-temperature alarm switches 4.3. Vacuum Receiver Tank: I. Construction: One (1) carbon steel receiver tank, minimum 80-gallon ASME-coded pressure vessel, vertical or horizontal orientation Exterior metal surfaces coated with epoxy or marine-grade coating Interior powder-epoxy lining All exterior hardware (bolts, fasteners, brackets) shall be 316 stainless steel II. Pressure & Temperature Ratings: Internal pressure rating: 75 PSI Vacuum rating: 15 PSI Operating temperature: -20°F to 200°F III. Included Receiver Features: Liquid-filled vacuum gauge Visual sight level gauge Inlet flexible connector 4.4. Equipment Piping and Mechanical Connections: I. All inlet and discharge piping shall be 316 stainless steel or PVC Schedule 80, suitable for outdoor corrosive wastewater-plant environments. II. All flexible connectors shall be rated for outdoor UV exposure. III. Inlet and discharge isolation valves shall be weather-rated. IV. Stainless steel (316 SS) inlet piping components shall be provided. V. All exposed metal surfaces shall have corrosion-resistant coatings. 4.5. Duplex Control Panel: I. Electrical & Construction: 460V, 3-Phase, 60 Hz supply UL-Listed NEMA 4X, 316 stainless steel enclosure Hinged door with 3-point latch and gasketed seal Factory wiring to motors, switches, and sensors 120V control transformer with fused primary and secondary Surge Protection Device (SPD) installed on incoming power Panel rated for outdoor operation, ambient temperature range -20°F to 120°F II. Pump Control Features: Full-voltage magnetic starters with 3-phase overload protection Individual HAND / OFF / AUTO selector switches 24-hour automatic alternation (lead/lag rotation) Vacuum transducer for adjustable sequencing Frequent start/stop protection Analog hour meters for each pump Any LCD screens exposed to sunlight shall include UV-protective covers III. Status & Alarm Indication: GREEN pump running lights (Pump 1 / Pump 2) RED high-temperature alarm lights (Pump 1 / Pump 2) BLACK individual motor overload reset buttons BLACK system ALARM RESET pushbutton RED emergency stop (E-STOP) button All pilot devices sealed for outdoor use and rated for water intrusion protection 4.6. System Highlights: I. Fully integrated duplex system for continuous and redundant operation. II. Oil-sealed rotary vane technology for long service life and proven reliability. III. ASME-rated receiver with corrosion-resistant interior/exterior protection. IV. All external metals protected via epoxy/marine-grade coatings and 316 stainless hardware. V. Stainless steel or Schedule 80 PVC piping for corrosion resistance. VI. UL-listed controls in a NEMA 4X stainless steel enclosure. VII. All performance metrics verified with a single pump operating; the second pump provides redundancy and automatic alternation for even wear. VIII. High-temperature shutdown and inlet filtration protect pump integrity. IX. All major components factory-mounted and wired for simplified field installation. 4.7. Startup, Documentation, and Warranty:
