Engineering Specifications for PCC Evaporative Condensers

Part 1: General

1.1 General: Furnish and install, Baltimore Aircoil Company model: _____ factory assembled evaporative condenser(s) of counterflow draw-through design, with multiple side air inlet, conforming in all aspects to the specifications and schedule as shown on the plans. 

1.2 Capacity: The evaporative condenser(s) shall be warranted by the manufacturer to have a heat rejection capacity of __________ BTUH (kW) , operating with _________ refrigerant and _______ºF (ºC) condensing temperature and ________ºF(ºC) entering wet-bulb temperature. 

1.3 Corrosion Resistant Construction (standard): Unless otherwise noted in this specification, all steel panels and structural members shall be constructed from heavy-gauge, G-235 (Z700 metric) hot-dip galvanized steel, with cut edges given a protective coating of zinc-rich compound. 

(Alternate) 1.3 Corrosion Resistant Construction (optional): Unless otherwise noted in this specification, all steel panels and structural members shall be protected with a thermosetting hybrid polymer. The corrosion resistance system shall consist of G-235 (Z700 metric) hot-dip galvanized steel prepared in a four-step (clean, pre-treat, rinse, dry) process with an electrostatically sprayed, thermosetting hybrid polymer, fuse-bonded to the substrate during a thermally activated curing stage and monitored by a 23-step quality assurance program. Any other coatings must be submitted to the engineer for pre-approval. Approved equals must have undergone testing, resulting in the following results as a minimum: 

a. When X-scribed to the steel substrate it shall be able to withstand 6,000 hours of a 5% salt spray per ASTM B117 without blistering, chipping, or loss of adhesion. 
b. When X-scribed to the steel substrate it shall be able to withstand 6,000 hours of exposure to acidic (pH=4.0) and alkaline (pH=11.0) water solutions at 95ºF (35˚C) without signs of chemical attack.
c. Shall withstand impact of 160 in-lbs per ASTM D2794 without fracture or delamination of the polymer layer. 
d. Shall withstand 6,000 hours of ultraviolet radiation equivalent to 120,000 hours of noontime sun exposure without loss of functional properties. 
e. Shall withstand 200 thermal shock cycles between -25ºF and +180ºF (-32˚C and 82˚C) without loss of adhesion or other deterioration. 
f. Shall withstand 6,000 hours of exposure to 60 psi (42,184 kg/m2) water jet without signs of wear or erosion. 

(Alternate) 1.3 Corrosion Resistant Construction (optional): Unless otherwise noted in this specification, all steel panels and structural members shall be constructed of type 304 stainless steel and assembled with type 304 stainless steel nut and bolt fasteners. 

(Alternate) 1.3 Corrosion Resistant Construction (optional): Unless otherwise noted in this specification, all steel panels and structural members shall be constructed of type 316 stainless steel and assembled with type 316 stainless steel nut and bolt fasteners.

(Alternate) 1.3 Corrosion Resistant Construction (optional): Unless otherwise noted in this specification, the basin and the adjacent panels which may come in contact with water shall be constructed from type 304 stainless steel. The rest of the unit shall be constructed from G-235 hot-dip galvanized steel.

1.4 Units shall have a self-aligning pan and casing section for easy rigging.

1.5 Warranty: The manufacturer’s standard equipment warranty shall be for a period of one (1) year from the date of startup or eighteen (18) months from the date of shipment, whichever ends first. The manufacturer shall, in addition, provide a five (5) year mechanical drive warranty covering the fans, fan shafts, bearings, sheaves, supports, and fan motors. An additional two years of warranty, for a total of seven (7) years, shall be provided for fan motor(s) when space heaters are field-wired at time of initial installation.

1.6 Factory Testing: Equipment manufacturer shall be capable of testing the operation of the condenser in the manufacturer’s own test facility. Test facilities shall be capable of simulating design conditions, including but not limited to design wet-bulb, airflow, refrigerant mass flow rate, refrigerant condensing temperature, and total heat rejection. 

1.7 Quality Assurance: The manufacture shall have a Management System certified by an accredited registrar as complying with the requirements of ISO-9001 to ensure consistent quality of products and services. Manufacturers that are not ISO-9001 certified shall provide an additional one-year warranty to the customer at no additional cost. 

1.8 Seismic Forces: The evaporative condenser shall be designed, tested, and certified in accordance with the 200912? IBC and ASCE/SEI 7-05.  The unit shall be suitable for applications with Design Spectral Acceleration at Short Period (SDS) for z/h = 1.0 up to  _____g with a Component Importance Factor (Ip) of 1.0 and 1.5.  The unit shall be certified by the manufacturer as functional following an earthquake.  The certification shall be based on full-scale, shake table testing conducted in accordance with ICC-ES Acceptance Criteria AC156, and shall be reviewed and approved by a licensed professional engineer independent of the manufacturer.  Experience data or analysis is not acceptable to verify post-earthquake functionality for Ip = 1.5.  Units not provided with evidence of shake table testing shall not be an acceptable alternative.
1.8 Wind Forces:  The evaporative condenser shall be designed in accordance with the 200912? IBC and ASCE/SEI 7-05.  The unit shall be suitable for applications with a design horizontal wind pressure up to _____psf.  Design wind pressure shall be calculated in accordance with Sections 6.5.15 and 6.5.15.1, as applicable, of ASCE/SEI 7-05.  A concurrent uplift pressure equivalent to the horizontal pressure shall be considered in the unit design.  Unit resistance shall be determined in accordance with the material design specifications referenced in the 200912? IBC, and shall be reviewed and approved by a licensed professional engineer independent of the manufacturer.
. Part 2: Parts 

2.1 Coil Casing Assembly 

2.1.1 Coil casing section: Evaporative condenser coil section shall consist of a refrigerant condensing coil, a spray water distribution system, and drift eliminators as indicated supplied? by the manufacturer. 

2.1.2 The refrigerant condensing coil shall be fabricated of continuous lengths of all prime surface steel at the manufacturer’s own facility, and hot-dip galvanized after fabrication (HDGAF). Maximum allowable working pressure shall be 300 psig (280 psig for coils supplied with a Canadian Registration Number (CRN)).  The refrigerant condensing coil shall be tested at 375 psig (2,687 kPa) air pressure under water. The refrigerant condensing coil shall be designed for low pressure drop and for free drainage of liquid refrigerant. The refrigerant condensing coil shall be ASME B31.5 compliant and coils shipping into Canada shall be supplied with a CRN. 

(Alternate) 2.1.2 Coil Assembly (Galvanized steel coil with additional circuit): The condensing coil shall be fabricated of continuous lengths of all prime surface steel at the manufacturer’s own facility, and hot-dip galvanized after fabrication. The condensing coil shall be designed for low pressure drop and for free drainage of liquid refrigerant. Maximum allowable working pressure shall be 300 psig (280 psig for coils supplied with a CRN). The coil header shall be partitioned. Each coil segment shall include an inlet and outlet connection to allow independent operation of each segment.

(Alternate) 2.1.2 Coil Assembly (ASME coil) : The condensing coil shall be fabricated of continuous lengths of all prime surface steel at the manufacturer’s own facility, and hot-dip galvanized after fabrication. The condensing coil shall be pneumatically tested at 375 psig (2,865 kPa). The condensing coil shall be designed for low pressure drop and for free drainage of liquid refrigerant. Maximum allowable working pressure shall be 300 psig (280 psig for coils supplied with a CRN). The condensing coil shall be designed, built, tested and stamped in accordance with Section VIII, Division 1, of the ASME Boiler and Pressure Vessel Code. 

2.2 Water Distribution System

2.2.1 Spray water distribution: Water shall be distributed evenly over the coil at a minimum flow rate of 4.5 gpm/ft2 (3.1 lps/m2) to ensure complete wetting of the coil at all times. The water distribution system shall have an operating pressure of 2 psig (115 kPa) at the evaporative condenser spray water inlet connection.

2.2.2 Nozzles: Large-diameter, non-clog, 360° plastic distribution nozzles spaced across the coil face area, shall utilize a two-stage diffusion pattern to provide overlapping, umbrella spray patterns. Nozzles shall have a minimum of 0.25” (6.35 mm) protrusion inside the spray branches to ensure unimpeded water flow between regular cleanings of the water distribution system. Nozzles shall be removable without any tools for cleaning. Directional nozzles shall not be acceptable.

2.2.3 Spray branches: Spray branches shall be held in place by snap-in rubber grommets, allowing quick removal of the complete spray branch for cleaning or flushing. Spray branches shall be removable without the use of any tools and constructed out of Schedule 40 PVC. 

2.2.4 Removable PVC drift eliminators shall be positioned to prevent moisture from leaving the evaporative condenser and incorporate a minimum of three (3) changes in air direction. 

2.3 Basin Assembly 

2.3.1 Basin: The basin shall be constructed of heavy-gauge G-235 (Z700 metric) hot-dip galvanized steel panels and structural members. The basin shall be sloped towards the pump inlet and shall include: a drain/clean-out connection, a steel strainer, a corrosion resistant make-up valve, overflow connection, and a water recirculation pump assembly. 

a. Drain/cleanout connection shall be located in the basin to allow removal of recirculating water. 
b. Lift-out steel strainer shall be supplied with perforated openings sized smaller than the water distribution nozzle orifices and an integral anti-vortexing hood to prevent air entrainment. 
c. Corrosion resistant make-up valve shall be supplied with a large diameter, foam-filled plastic float arranged for easy adjustment. 
d. Overflow connection shall be provided in the cold water basin to protect against recirculating water spillage.

(Alternate) 2.3.1 Basin: The basin shall be constructed out of type 304 stainless steel with seams welded at the factory. A bolted stainless steel basin is not an acceptable alternative. The basin shall have single side air inlet and integral air plenum. The basin shall be sloped towards the pump inlet and shall include: a drain/clean-out connection; a steel strainer; a corrosion resistant make-up valve; overflow connection; and a water recirculation pump assembly. 

a. Drain/cleanout connection shall be located in the basin to allow removal of recirculating water. 
b. Lift-out steel strainer shall be supplied with perforated openings sized smaller than the water distribution nozzle orifices and an integral anti-vortexing hood to prevent air entrainment. 
c. Corrosion resistant make-up valve shall be supplied with a large diameter, foam-filled plastic float arranged for easy adjustment. 
d. Overflow connection shall be provided in the basin to protect against recirculating water spillage. 

(Alternate) 2.3.1 Basin: The basin protected with TriArmorTM Corrosion Protection System: The basin shall be protected with the TriArmorTM Corrosion Protection System. The system shall consist of G-235 galvanized steel encapsulated with a thermosetting hybrid polymer further protected by a polyurethane liner, factory applied to all submerged surfaces. The polyurethane barrier shall seal all factory seams in the basin to ensure a corrosion resistant and water tight construction, and shall be warranted against leaks and corrosion for five (5) years. Field applied polyurethane or polyurethane applied directly to galvanized steel is not an acceptable alternative. Standard basin accessories shall include: a corrosion resistant make-up valve with large diameter polystyrene filled plastic float for easy adjustment of the operating water level, removable anti-vortexing device to prevent air entrainment, and large area lift out strainers with perforated openings sized smaller than the water distribution system nozzles. The strainer and anti-vortexing device shall be constructed of type 304 stainless steel to prevent corrosion. A welded type 304 or 316 stainless steel basin shall be an acceptable alternative; provided the basin is warranted against leaks and corrosion for a period of at least 5 years. A bolted type 304 stainless steel basin shall not be an acceptable alternative.

a. Drain/cleanout connection shall be located in the cold water basin to allow removal of recirculating water. 
b. Lift-out steel strainer shall be supplied with perforated openings sized smaller than the water distribution nozzle orifices and an integral anti-vortexing hood to prevent air entrainment. 
c. Corrosion resistant make-up valve shall be supplied with a large diameter, foam-filled plastic float arranged for easy adjustment. d. Overflow connection shall be provided in the basin to protect against recirculating water spillage. 

2.3.2 Water recirculation pump: shall be a close-coupled, bronze-fitted centrifugal pump equipped with a mechanical seal, mounted on the basin and piped from the suction strainer to the water distribution system. The pump shall have a bronze impeller.  The pump shall be installed so that it may drain freely when the basin is drained. The pump assembly shall include an integral metering valve and bleed line to control the bleed rate from the pump discharge to the overflow connection. The pump motor shall be totally enclosed fan cooled (TEFC) type suitable for _____ V, ____ phase, ______ Hz electrical service. 

2.3.3 Remote sump option: On installations requiring a remote sump, the evaporative condenser shall be constructed to accommodate the use of an independent sump and pump for recirculating water (by others). The recirculating water pump, steel strainer, make-up valve, and integral bleed line assemblies shall be omitted from the evaporative condenser scope of supply. The evaporative condenser shall be supplied with a basin outlet sized and located as indicated on the drawings for gravity drain to the remote sump.

Part 3: Mechanical Equipment

3.1 Fan(s):  Fan(s) shall be located on the discharge side of the unit.  Fan(s) shall be heavy-duty, axial flow type with aluminum alloy blades driven by a one-piece, multi-groove neoprene/polyester belt designed for a minimum of 150% of the motor nameplate horsepower.  

3.2 Fan Motors: Fan motors and drives shall be located at the top of the unit to minimize discharge sound levels.  Fan motor bases shall be adjustable for belt tensioning by adjusting a single nut. Fan motor(s) shall be totally enclosed fan cooled air over (TEAO) type, premium efficiency/VFD ready with a 1.15 service factor, suitable for _____ V, ____ phase, ______ Hz electrical service and shall be mounted on an easily adjusted, heavy-duty motor base. Fan motors shall comply with NEMA Standard MG 31, Section IV, Part 31.

3.3 Bearings: Fan shafts shall be mounted in heavy-duty, self-aligning, grease-packed relubricatable ball bearings with eccentric locking collars, designed for a minimum L10 life of 95,000 hours (1,000,000 hours average life). Bearing lubrication lines shall be extended to the exterior of the unit.

3.4 Sheaves: Fan and motor sheaves shall be fabricated from corrosion-resistant materials. 

3.5 Mechanical Equipment Warranty: The fan(s), fan shaft(s), bearings, mechanical equipment support and fan motor shall be warranted against defects in materials and workmanship for a period of five (5) years from date of shipment.

Part 4: Optional Equipment Specifications 

4.1 Basin Sweeper Piping: The basin of the unit shall be equipped with PVC sump sweeper piping for a separator (supplied by others). I thought we had a more detailed description…perhaps found with another condenser family?

4.2 Basin Water Level Control: The evaporative condenser manufacturer shall provide an electric water level control (EWLC) system. The system shall consist of water level sensing and control units in quantities and locations as indicated on the drawings. Each water level sensing and control unit shall consist of the following: NEMA 4 enclosure with gasketed access cover; solid state controls including all necessary relays and contacts to achieve the specified sequence of operation; stainless steel water level sensing electrodes with brass holder. Provide PVC union directly below the control enclosure to facilitate the removal and access of electrodes and control enclosure. (Optional) The number and position of water level sensing electrodes shall be provided to sense the following: high water level, low water level, high water alarm level, low water alarm level, and heater safety cutout.

4.3 Basin Heaters: Evaporative condenser shall be provided with basin heaters to prevent freezing of the water in the cold water basin when the evaporative condenser is idle. The basin heaters shall be selected to maintain +40° F (4.4° C) basin water temperature at a -20F (-28.9°C) ambient temperature and 10 mph (16.1 km/hr) wind speed. Basin heaters shall be electric immersion type controlled by a remote thermostat with the sensing bulb located in the basin water. Basin heaters shall be provided with a factory-installed low water level cutout switch to prevent heater operation unless the heater elements are fully submerged. 

4.4 Vibration Cutout Switch (VCOS): Provide an electronic remote reset vibration switch with contact for BAS monitoring. Wiring shall be by the installing contractor. The electronic vibration cutout switch shall be set to trip at a point so as not to cause damage to the unit. To ensure this, the trip point will be set in a frequency range of ___ to ___ Hertz and a trip point of ____ in/sec (____m/sec).

4.5 External Access: Evaporative condenser shall be provided with a factory assembled, field-installed external platform with an access ladder and handrails complying with OSHA standards and regulations to provide access to the top of the evaporative condenser. External platform shall have a 24” (610 mm) wide non-skid walking surface and 42” (1,220 mm) high safety railings. Optional safety cage shall be available to meet OSHA requirements as necessary. 

4.7 Single Point Factory Wiring: The evaporative condenser shall be provided with a UL-Listed Stainless Steel NEMA 3R Electrical Box and wires run in UL-Listed conduit from the Box to all electrical components on the unit, including Fan(s), Pump(s), and optional VCOS, EWLC + Solenoid and Basin Heater.