LRWB Closed Circuit Cooler
The LRWB is a low noise, low height, forced draft, centrifugal fan design closed circuit cooler with a capacity range of 142 to 3,335 MBH (41 to 977 kW). Standard construction features the patented, high efficiency Thermal-Pak® Coil with a type 304 stainless steel cold water basin and G-235 (Z725 Europe) galvanized steel casing. Type 304 stainless steel construction is available for the casing.
The LRWB Closed Circuit Cooler product line is a combination of EVAPCO’s extensive forced draft evaporative cooling product experience and engineered solutions design philosophy. Using EVAPCO's patented, high-efficiency THERMAL-PAK® coil, the LRWB is the most efficient, quietest, and easiest forced-draft cooler in the industry to maintain and operate. All units are designed with IBC Compliant construction and CTI Certified Thermal Performance. The LRWB’s engineered design features are described below.
- Principle of Operation
- IBC Compliant
- Thermal-Pak Coil
- Efficient Drift Eliminators
- Quiet Operation
- Corrosion Protection
- Pressurized Water Distribution System
- LRWB Ships Factory Assembled
- Fast, On-Time Shipments
Principle of Operation
The process fluid is circulated through the coil of the closed circuit cooler. Heat from the process fluid is dissipated through the coil tubes to the water cascading downward over the tubes. Simultaneously air is blown through the unit by the fans and travels upward over the coil opposite the water flow. A small portion of the water is evaporated which removes the heat. The warm moist air is forced to the top of the closed circuit cooler by the fan and is discharged to the atmosphere. The remaining water falls to the sump at the bottom of the cooler where it is re-circulated by the pump up through the water distribution system and back down over the coils.
What is IBC?
- The International Building Code requires that evaporative cooling equipment must meet the same seismic or wind load forces as the building to which they are attached.
How does it apply?
- Based on project zip code and site design factors, calculations are made to determine the equivalent seismic "g force" and wind load on the unit.
What does EVAPCO offer?
- Standard Structural Design
-Projects with ≤ 1.0g seismic or 145 psf wind loads
- Upgraded Structural Design
-Projects with > 1.0g seismic or 145 psf wind loads
- The upgraded structural design package for the New ATWB is designed for 5.12g and 145psf, making it applicable to ALL building locations in North America.
Evapco Closed Circuit Coolers utilize EVAPCO's patented Thermal-Pak® coil design which assures greater operating efficiency. The elliptical tube design allows for closer tube spacing, resulting in greater surface area per plan area than round-tube coil designs. In addition, the Thermal-Pak® design has lower resistance to airflow and also permits greater water loading, making the Thermal-Pak® coil the most effective design available.
The coils are manufactured from high quality steel tubing following the most stringent quality control procedures. Each circuit is inspected to ensure the material quality and then tested before being assembled into a coil. Finally, the assembled coil is pneumatically tested at 400 psig under water to ensure it is leak free. To protect the coil against corrosion, it is placed in a heavy steel frame and then the entire assembly is dipped in molten zinc (hot-dip galvanized) at a temperature of approximately 800°F.
Note: Closed circuit coolers should only be used on sealed, pressurized systems. Continual aeration of the water in an open system can cause corrosion inside the tubes of the cooler leading to premature failure.
Efficient Drift Eliminators
The LSWB & LRWB are provided with an efficient drift eliminator system that effectively reduces entrained water droplets from the air discharge to less than 0.001% of the spray water flow rate. The eliminators are constructed of non-corrosive PVC with a multi-pass design for maximum drift reduction. They are assembled in modular sections for easy removal and access to the water distribution system. In addition to reducing drift, the eliminators also function as effective debris screens which protect the spray system from sunlight and debris.
G-235 Hot-Dip Galvanized Steel Construction
The standard material of construction for evaporative cooling equipment for many years has been hot-dip galvanized steel. The purpose of galvanizing is to protect the base metal from corrosion, and the thickness of the galvanized layer directly affects the equipment life. EVAPCO has been instrumental in the development of corrosion protection technology and was the first manufacturer to use G-235 galvanized steel construction. The G-235 designation equates to a minimum of 2.35 ounces of zinc per square foot of surface area.
The EVAPCOAT Corrosion Protection System is the heaviest galvanized coating available for extended corrosion protection eliminating the need for costly, unreliable epoxy paint finishes.
Stainless Steel Material Options
The LRWB is standard with a stainless steel cold water basin. Optional upgrades to stainless steel water touch basins, stainless steel water touch units and all stainless steel construction are also available.
For more information on these stainless steel options, see your local EVAPCO sales representative.
Maintenance Free ZMII® Spray Nozzle Water Distribution System
EVAPCO’S Zero Maintenance ZMII® Spray Nozzle remains clog-free while providing even and constant water distribution for reliable, scale-free evaporative cooling under all operating conditions. The heavy duty nylon ZMII® Spray Nozzles have a 1-5/16” diameter opening and a 1-1/2” splash plate clearance enabling EVAPCO to use 75% fewer nozzles. Furthermore, the fixed position ZMII® nozzles are mounted in corrosion-free PVC water distribution pipes that have threaded end caps. Together, these elements combine to provide unequaled coil coverage and scale prevention, and make the industry’s best performing non-corrosive, maintenance-free water distribution system. The water distribution is designed to provide a minimum 6 GPM over each square foot (4 liters per second over each square meter) of unit plan area to ensure proper flooding of the coil.
LRWB Ships Factory Assembled
The compact, unitary design of the LRWB Closed Circuit Cooler allows them to be shipped completely assembled. This results in lower transportation costs and no assembly requirements at the job site. Only one lift is required to rig the LRWB. Note: Options such as attenuation and discharge hoods will require additional lifts.
Fast, On-Time Shipments
The LRWB is completely factory assembled and manufactured by a dedicated professional workforce, expert in building closed circuit coolers. Factory trained mechanics and EVAPCO's strict quality control and inspection procedures guarantee the quality of every unit shipped.
EVAPCO's controlled factory environment ensures fast on-time shipments, allowing the LRWB to be available WHEN THE CUSTOMER WANTS IT!
Designed for easy maintenance, the LRWB Closed Circuit Cooler leads the industry in service friendly features. The three most critical areas for closed circuit cooler maintenance are the basin, drive system and coil. The LRWB cold water basin is constructed of Type 304 Stainless Steel for low maintenance and long life and is easily accessed from outside the tower. All drive system components are located in the dry, entering air stream and can be serviced from outside the tower without removing the fan screens, even with full sound attenuation! The exclusive THERMAL-PAK® coil is designed for trouble-free maintenance and long life straight from the factory.
- Stainless Steel Cold Water Basin
- Stainless Steel Strainers
- Mechanical Drive System Access
- Motor Mount and Belt Adjustment
- Fan Access
- Thermal-Pak Coil
- End Mounted Recirculating Pump
Stainless Steel Cold Water Basin
The basin of the closed circuit cooler is the most susceptible area to accelerated corrosion from turbulent mixing of air and water and silt build-up than any other part of the cooler. EVAPCO provides as standard, the most effective corrosion protection available for the basin – type 304 stainless steel construction. The entire cold water basin including the suction strainers are constructed of type 304 stainless steel for maximum protection from the effects of corrosion. Other types of coatings cannot provide the same maintenance-free operation and cooler longevity available from the stainless steel construction.
Stainless Steel Strainers
The EVAPCO standard for many years, the stainless steel strainer is one component of the closed circuit cooler subject to excessive wear and corrosion. With stainless steel construction, this component will last the life of the closed circuit cooler.
Mechanical Drive System Access
The LRWB mechanical drive system is easy to maintain. Bearing lubrication is made easy with extended lubrication lines brought to the outside of the fan and drive enclosure. These connections are still accessible even with all of the LRWB’s additional sound attenuation options. A large motor access door is located on the side of the fan and drive enclosure for quick and easy access to the motor for routine maintenance or removal. There is no need to remove fan screens to maintain the key drive components.
Motor Mount and Belt Adjustment
All LRWB models have TEFC motors mounted on an adjustable motor base. This adjustable base design allows belt tensioning to be performed externally without removing the fan screens. The locking mechanism used to maintain belt tension can also be used as wrench to adjust belt tension. This screw operated adjustment is extended through the LRWB’s optional intake sound attenuator for easy adjustment even with full intake attenuation.
The split fan housing on the LRWB allows quick removal of the fans from the front end of the unit. This feature allows for easy fan removal when units are placed side by side where space is minimal.
EVAPCO’s exclusive elliptical Thermal-Pak coil is manufactured at EVAPCO from high quality steel tubing following the most stringent quality control procedures. Each circuit is inspected to assure the highest material quality and then is tested at 400 psig (2758 kPa) under water to ensure it is leak free. To protect the coil against corrosion, it is placed in a heavy steel frame and then the entire assembly is dipped in molten zinc (hot-dip galvanized) at a temperature of approximately 800º F (427º C). The tubes are pitched in the direction of fluid flow to provide good liquid drainage.
NOTE: Closed Circuit coolers should only be used on sealed, pressurized systems. Continual aeration of the water in an open system can cause corrosion inside the tubes of the cooler leading to premature failure.
End Mounted Recirculating Pump
All LRWB models feature a horizontal pump mounted at the open, connection end of the unit. This location makes pump maintenance easy as access is free and unobstructed.
The LRWB Closed Circuit Cooler features the highly successful EVAPCO V-belt drive system engineered for heavy-duty operation. All drive system components including the fans, motors, sheaves, and belts are located in the dry entering air stream and are suitable for the most severe duty closed circuit cooler applications. The entire drive system is backed with a comprehensive (5) Five Year Warranty.
All EVAPCO Closed Circuit Coolers come standard with premium efficient, inverter capable fan motors that can be used with variable frequency drive (VFD) systems for precise capacity control. VFD systems can control the speed of a fan motor by modulating the voltage and frequency of the motor input electrical signal. When connected to a building automation system a VFD can receive signals and vary the fan speed to meet demand loads. This popular method of capacity control can yield significant energy savings.
Evapco offers two-speed fan motors as an option for alternative capacity control. In periods of lightened loads or reduced wet bulb temperatures the fans can operate at low speed providing about 60% of full speed capacity yet consuming only about 15% of full speed power. In addition to the energy savings the sound levels of the unit can be greatly reduced by operating at low speed. These motors do not require the use of VFD systems however they can only operate at two speeds: full or low.
Pony motors are available as another capacity control method. Pony motors are smaller fan motors for use in times of reduced loading. The pony motor is typically 1/4 of the HP of the primary motor and can significantly reduce energy requirements.
The belt drive system consists of multigrooved V-Belts with high lateral rigidity. The belts are designed for closed circuit cooler service, and are constructed of neoprene with polyester cords. The belt drive is sized for 150 percent of the motor nameplate horsepower ensuring long and trouble free operation.
Centrifugal Fans and Drives
The LRWB features forwardly curved centrifugal fan wheels constructed of hot-dip galvanized steel for strength and efficiency. All fans are statically and dynamically balanced and mounted in a hot-dip galvanized steel housing designed and manufactured by EVAPCO. The drive sheaves are located in the dry entering air stream for longer life and are accessible from the side of the fan and drive enclosure.
Fan Shaft and Bearings
All LRWB models feature a solid steel shaft for long, reliable shaft life. Other brands may use two-piece shafts with welded end journals that are susceptible to rusting and premature failure. The shaft is supported with heavy duty end bearings and no center bearing thereby simplifying maintenance concerns.
Five (5) Year Warranty
EVAPCO provides a standard (5) five year motor and drive warranty on all LRWB products. This unique warranty is designed to offer the end user optimum protection against fan drive and motor failure. It is a comprehensive plan which includes the fan(s), fan shaft, belts, sheaves, shaft bearings and motor.
The standard design of the EVAPCO LRWB provides the customer with the easiest Closed Circuit Cooler to maintain in the industry. There are additional options which can make maintenance easier, and extend the life, or enhance the performance capabilities of the Closed Circuit Cooler. These options are listed below.
- 304 Stainless Steel Coil
- Sound Attenuation
- Extended Surface Coil
- Discharge Hood with Positive Closure Dampers
- Electric Water Level Control
- Pulse~Pure Water Treatment System
- Freeze Protection
- Other Options
Stainless Steel Coils
EVAPCO now offers the optional TITAN COIL. Constructed with type 304L Stainless Steel, the TITAN COIL is manufactured using EVAPCO's patented elliptical tube Thermal-Pak® coil design upgraded to Xtra Tough construction featuring: Xtra Durability, Xtra Corrosion Resistance, and an Xtra long 5 YEAR Coil Warranty as standard.
If the standard LRWB sound pressure level is not quiet enough for certain applications, the sound levels can be further reduced by adding various stages of sound attenuation. The sound attenuation options of the LRWB can be provided in stages and will provide varying degrees of attenuation based on the stage of attenuation selected. Consult your local EVAPCO sales representative for Factory Certified Sound Data for each option.
Fan Side Inlet Attenuation
Reduces sound radiated from the fan side air intakes and has an open bottom to allow for air entry. This attenuation package ships loose to be mounted in the field on each side of the cooling tower over the fan intakes.
Fan End Inlet Attenuation
Reduces sound radiated through the far end air intake. It consists of baffled panels to change the path of the air entry and to capture the radiated noise thus reducing the overall sound levels generated. In addition, the external belt adjustment mechanism is extended through the inlet attenuator to allow easy belt adjustment without having to enter the unit.
The discharge attenuation hood features a straight sided design with insulated baffles to reduce the overall sound levels of the discharge air. The discharge attenuation incorporates a large access panel to allow entry to the drift eliminators and water distribution system. If a higher discharge velocity is required, a tapered discharge hood providing minimal sound attenuation is available.
Extended Surface Coil
Closed Circuit Coolers can be provided with spiral fins on the heat exchanger coil to increase the dry performance of the unit. Dry performance is accomplished by rejecting heat to the atmosphere without the use of the spray pump and the evaporation process. Dry operation can be practical in cold climates and/or when reduced winter loads exist. The quantity of finned rows can be varied to optimize dry performance. See your local sales representative for more information.
Discharge Hood with Positive Closure Dampers
When a closed circuit cooler is used in a water-to-air heat pump system or in certain process cooling applications, a method of reducing the heat loss during idle periods of wintertime operation may be required. For these cases, an optional discharge hood with positive closure dampers and damper actuator is available.
The discharge hood with dampers is designed to minimize the heat loss from convective airflow through an idle cooler. Further reductions in heat loss may be obtained with the addition of insulation to the hood and casing, minimizing conductive heat losses. Insulation may be factory-installed on the hood and casing or field-installed by an insulation contractor.
The discharge hood and dampers are constructed of hot-dip galvanized steel. Hoods are equipped with access panels to facilitate maintenance on the eliminators and water distribution system. The dampers, damper actuator and linkage(s) are all factory- assembled. Actuator controls and wiring are field-supplied by others. Damper actuators require 120 volt power supply.
The system control sequence should provide for dampers to be fully open before the fans are running and closed when the fans are off; the damper actuator must be interlocked with the temperature control system for this purpose. When a centrifugal fan model uses a tapered discharge hood, the next larger size fan motor may be needed in order to overcome the additional static pressure.
Heat loss data is provided for standard units without hoods, with hoods and with hoods and insulation. Table ratings are based on 50°F water in the coil, -10°F ambient and 45 MPH winds (fan and pump off) and can be found in the LSWB/LRWB catalog. The catalog is available electronically under the Product Features & Engineering Brochures section of this website.
Electric Water Level Control
EVAPCO closed circuit coolers are available with an optional electric water level control system in place of the standard mechanical makeup valve and float assembly. This package provides very accurate control for the basin water level and does not require field adjustment, even under varying operating conditions.
The control was designed by EVAPCO and is manufactured exclusively for EVAPCO. It consists of multiple heavy duty stainless steel electrodes. These electrodes are mounted external to the unit in a vertical stand pipe. For winter operation, the stand pipe must be wrapped with electric heating cable and insulated to protect it from freezing.
The weather protected slow closing solenoid valve(s) for the makeup water connection is factory supplied and is ready for piping to a water supply with a pressure between 25 and 50 psig (138 kPa and 345 kPa).
If the units are installed in a cold climate and operated year-round, freeze protection must be provided for the heat exchanger coil in the unit as well as for the recirculating water system.
Recirculating Water System Freeze Protection Options
Remote Sump Configuration
The surest way to protect the recirculating water system from freezing is with a remote sump. The remote sump should be located inside the building and below the unit. When a remote sump arrangement is selected, the spray pump is provided by others and installed at the remote sump. All water in the closed circuit cooler basin should drain to the remote sump when the spray pump cycles off.
Basin Heater Package
If a remote sump configuration is not practical, electric basin heater packages are available to keep the pan water from freezing when the unit cycles off. Water lines to and from the unit, spray pump and related piping should be heat traced and insulated up to the overflow level to protect from freezing. The unit should not be operated dry (fans on, pump off) unless the basin is completely drained and the unit has been designed for dry operation. Consult your local sales representative when dry operation is a requirement.
Steam or Hot Water Coils
Pan coils are available as an alternate to using electric basin heaters or a remote sump. Constructed of galvanized pipe and installed in the closed circuit cooler basin, they are supplied without controls and are ready for piping to an external steam or hot water source. Pan water heater controls should be interlocked with the water circulating pump to prevent their operation when the pump is energized.
Heat Exchanger Coil Freeze Protection Options
The simplest and most foolproof method of protecting the heat exchanger coil from freeze-up is to use a glycol solution. If this is not possible, an auxiliary heat load must be maintained on the coil at all times so that the water temperature does not drop below 50°F when the cooler is shut down and, a minimum recommended flow rate per unit must be maintained. See pages 35 to 36 of the LSWB/LRWB catalog for more information. The catalog is available electronically under the Product Features & Engineering Brochures section of this website.
If an anti-freeze solution is not used, the coil must be drained immediately whenever the pump is shut down or flow stops. Care must be taken to ensure that the piping is sized to allow the water to flow quickly from the coil. This method of freeze control should only be used in an emergency situation. Coils should not be drained for an extended period of time. Leaving the coil drained and open to the atmosphere can cause corrosion inside the tubes which may lead to premature coil failure.
The amount of glycol required for a system will depend upon the total volume of water in the closed loop and the winter ambient conditions for the installation. The Engineering Data Tables presented on pages 13-29 of the LSWB/LRWB catalog provide the water volume contained inside the cooler coils to assist in this calculation.
Additional Stainless Steel Material Options
Stainless Steel Fan Shafts
Solid Screened Bottom Panels
Hot Water or Steam Coils
Motors– Energy Efficient / Inverter Duty / 2S/1W and 2S/2W / Mill and Chem Duty Arctic Duty and Many More, Consult the Factory
|LRWB Specification||61 KB|
1.1 RELATED DOCUMENTS
A. Drawings and general provisions of the Contract, including General and Supplementary Conditions and Division 1 Specification Sections, apply to this section.
A. This Section includes factory assembled and tested, closed-circuit forced-draft cooling tower (also known as a closed circuit cooler).
A. General: Submit the following:
1. Certified drawings of the closed circuit cooler, sound data, recommended steel support indicating weight loadings, wiring diagrams, installation instructions, operation and maintenance instructions, and thermal performance guarantee by the manufacturer.
1.4 QUALITY ASSURANCE
A. Verification of Performance:
1. Test and certify closed circuit cooler thermal performance according to CTI Standard 201.
2. Test and certify closed circuit cooler sound performance according to CTI ATC-128.
B. Meet or Exceed energy efficiency per ASHRAE 90.1.
A. Motor/Drive System: Five (5) year comprehensive warranty against materials and workmanship including motor, fan, bearings, mechanical support, sheaves, bushings and belt.
B. Unit: One (1) year from start-up, not to exceed eighteen (18) months from shipment on the unit.
A. Manufactures: Subject to compliance with requirements, provide closed circuit cooler manufactured by one of the following:
1. EVAPCO, Inc.
2. Approved Substitute
A. Galvanized Sheet Steel casing and fan housing complying with ASTM A 653/A 653M and having G-235 designation and Type 304 Stainless Steel basin.
B. Optional Type 304 and/or 316 Stainless Steel as specified.
2.3 FORCED-DRAFT, CLOSED CIRCUIT COOLER
A. Description: Factory assembled and tested, forced draft closed circuit cooler complete with heat transfer coil, fan(s), fan screens, accessories, and rigging supports.
B. Closed Circuit Cooler Characteristics and Capacities: Refer to the Closed Circuit Cooler schedule.
1. Type and Material: forward curved, centrifugal of hot-dipped galvanized construction. The fans shall be factory installed, and statically and dynamically balanced for vibration free operation.
2. Fan Housing: The complete drive system, including the electric motor, belts, bearings, fan, and drives shall be completely enclosed in a protective housing which covers the drive system and provides sound reduction.
3. Maximum sound pressure level of ____dB(A) measured at 5 feet from the fan inlet during full speed operation in accordance with CTI Standard ATC-128.
D. Water Distribution System: Non-corrosive materials.
1. Evenly distribute of water over heat transfer coil with pressurized spray tree.
a. Pipes: Schedule 40 PVC, Non-corrosive Materials
b. Nozzles: Non-clogging, nylon, threaded into branch piping.
2. Maximum pressure at inlet shall be ____ psig.
E. IBC Compliance: The unit structure shall be designed, analyzed, and constructed in accordance with the latest edition of the International Building Code (IBC) Regulations for seismic loads up to ____ g and wind loads up to ____ psf.
F. Collection Basin Material: Type 304 Stainless Steel or Heavy Gauge G-235 Galvanized Steel (Optional) for long life and durability:
1. Removable Type 304 Stainless Steel strainer with openings smaller than nozzle orifices.
2. Joints: Bolted and sealed watertight.
3. Overflow, Makeup and Drain connections: G-235 Galvanized Steel (MPT and FPT).
G. Casing: Heavy Gauge G-235 Galvanized Steel or Type 304 Stainless Steel (Optional):
1. Casing panels shall totally encase all sides of the heat transfer surface to protect it from direct exposure to environmental elements. All galvanized steel panel edges shall be coated with a 95% pure zinc compound during fabrication.
2. Fasteners: Corrosion resistance equal to or better than materials being fastened.
3. Joints: Sealed watertight.
4. Welded Connections: Continuous and watertight
H. Heat Transfer Coil: Heavy Gauge G-235 Galvanized Steel encased in a steel framework, assembly hot-dip galvanized after construction. Type 304 Stainless Steel Optional. Coil assembly completely enclosed and protected from sunlight exposure, environmental elements and debris. Tubes sloped for free drainage of the coil and designed for low pressure drop. Coil assembly pneumatically tested at 400 psig under water. Coil connections beveled for weld, flanged (optional) or grooved (optional).
I. Drift Eliminators: PVC, for long life and durability resistant to rot, decay and biological attack; formed, bonded together for strength and durability in block format for easy removal and replacement; self extinguishing with flame spread rating of 5 per ASTM E84-81a; 0.001% drift rate.
J. Water Level Control: Brass mechanical makeup water valve and plastic float with an adjustable linkage.
K. Water Recirculation Pump: Close-coupled, centrifugal type with mechanical seal. The pump motor shall be ____ horsepower totally enclosed for outdoor service on ____ volts, ____ hertz, and ____ phase.
2.4 MOTORS AND DRIVES
A. General requirements for motors are specified in Division 23 Section "Motors".
B. Enclosure Type: TEFC
C. Fan Motor Speed: Premium Efficient VFD Duty (Option: 2-speed)
D. Drive: Power Band Belt designed for 150% of the motor nameplate HP.
1. Belt: V-belt type neoprene.
2. Sheaves: Aluminum alloy, taper lock design.
3. Bearings: Heavy duty, self-aligning bearings with extended grease lines and fittings.
4. Fan Shaft: Solid steel shaft with forged bearing journals.
5. Vibration Cutout Switch (Optional): Mechanical switch to de- energize fan motors if excessive vibration in NEMA 4 enclosure.
2.5 MAINTENANCE ACCESS
A. Access Door: A circular access door shall be located above the basin to allow for easy access to the pan interior.
B. Ladders (Optional): Aluminum, vertical complying with 29 CFR 1910.27.
2.6 SOUND ATTENUATION (OPTIONAL)
A. Inlet Attenuation: Materials to be same as fan section. Baffled panels shall change the path of air entry and capture radiated noise. External belt adjustment and lubrication points shall be provided.
B. Discharge Attenuation: Straight-sided discharge hood with insulated baffles to reduce the overall sound level of the discharge air. A large access panel to allow access to the water distribution system and drift eliminators shall be provided.
- Design Features
- Maintenance Features
- Drive Systems
- Optional Equipment
- Unit Specifications
- Thermal Performance
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