VESSELS / VALVES
The LPT is a low noise, low height, forced draft, centrifugal fan design cooling tower with a capacity range of 27 to 331 nominal tons (119 to 1455 kW). Standard construction consists of type 304 stainless steel cold water basin and G-235 (Z-725 Europe) galvanized steel casing with all type 304 stainless steel construction available.
LPT Cooling Tower - Design Features
The LPT Cooling Tower product line is a combination of EVAPCO's extensive forced draft cooling tower experience and engineered solutions design philosophy. The result is the quietest, easiest forced-draft tower in the industry to maintain and operate.
Principle of Operation
Warm water from the heat source is pumped to the water distribution system at the top of the tower. The water is distributed over the wet deck fill by means of large orifice nozzles. Simultaneously, air is forced through the air inlet louvers at the base of the tower and travels upward through the wet deck fill opposite the water flow. A small portion of the water is evaporated, which removes the heat from the remaining water. The warm moist air is forced to the top of the cooling tower by the fan(s) and discharged to the atmosphere. The cooled water drains to the basin at the bottom of the tower and is returned to the heat source.
The vertical air discharge of the LPT design and the distance between the discharge air and fresh air intakes, reduces the chance of air recirculation, since the warm humid air is directed up and away from the unit. For detailed layout information please consult EVAPCO's Equipment Layout Guideline
Efficient Drift Eliminators
An extremely efficient drift eliminator system is standard on the LPT Cooling Tower. The system removes entrained water droplets from the air stream to limit the drift rate to less than 0.001% of the recirculating water rate. With a low drift rate, the LPT Cooling Tower saves valuable water and water treatment chemicals. The LPT can be located in areas where minimum water carryover is critical, such as parking lots.
The drift eliminators are constructed of an inert polyvinyl chloride (PVC) plastic material which effectively eliminates corrosion of these vital components. They are assembled in sections to facilitate easy removal for inspection of the water distribution system.
The patented EVAPAK® fill design used in the LPT Cooling Tower is specially designed to induce highly turbulent mixing of the air and water for superior heat transfer. Special drainage tips allow high water loadings without excessive pressure drop. The fill is constructed of inert polyvinyl chloride, (PVC). It will not rot or decay and is formulated to withstand water temperatures of 130ºF (54,4ºC). Because of the unique way in which the crossfluted sheets are bonded together, and the bottom support of the fill section, the structural integrity of the fill is greatly enhanced, making the fill usable as a working platform. The fill selected for the Cooling Tower has excellent fire resistant qualities. Cooling Tower fill has a flame spread rating of 5 per ASTM-E84-81a. A higher temperature fill is available for water temperatures exceeding 130ºF (54,4ºC).
Sound Attenuation Packages
The standard LPT is the quietest, low silhouette centrifugal fan cooling tower in the industry. This is achieved by providing the first stage of inlet sound attenuation as part of the LPT's standard design. The LPT drive system, including the fan housing(s), electric motors, belts, bearings and drives, is completely enclosed by a protective housing which covers the drive system and also provides a significant level of sound reduction.
If the standard LPT sound pressure level is not quiet enough for certain applications, the should levels can be further reduced by adding various stages of sound attenuation. The sound attenuation options of the LPT can be provided in stages and will provide varying degrees of attenuation based on the stage of attenuation selected.
Pressurized Water Distribution System
The water distribution system is made of schedule 40 PVC pipe and ABS plastic water diffusers for corrosion protection in this key area. The piping is easily removable for cleaning. The water diffusers have a minimum opening of 3/8 by 1 inch (9,5 mm by 25,4 mm) and are practically impossible to clog. They also have an anti-sludge ring extending into the headers to prevent sediment from building up in the diffuser opening In addition, the spray branches have threaded end caps to allow easy debris removal.
The spray pressure for all LPT Cooling Towers is between 1 and 6 psig (6,9 and 42 kPa) at the
inlet header. The actual spray pressure will be shown on the certified drawings which are prepared for each unit.
Principle of Operation
Efficient Drift Eliminators
Sound Attenuation Packages
Presurized Water Distribution
Designed for easy maintenance, the LPT cooling tower leads the industry in service friendly features. The two most critical areas for cooling tower maintenance are the basin and the drive system. The LPT 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!
Stainless Steel Cold Water Basin
The basin of the cooling tower 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 cooling tower. 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 tower longevity available from the standard stainless steel construction.
Cold Water Basin Access
The LPT stainless steel cold water basin can be easily maintained from the sides of the cooling tower through large, circular access doors. The unique stepped configuration of the LPT heat transfer section allows unimpeded access to the basin to allow adjustment of the float assembly, removal of the stainless steel strainers and basin cleaning. This feature is not found on any other manufacturer’s products.
Mechanical Drive System Access
The LPT 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 LPT’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 Alignment
All LPT 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 LPT’s optional intake sound attenuator for easy adjustment even with full intake attenuation
The split fan housing on the LPT 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.
Stainless Steel Basin
Cold Water Basin Access
Mechanical Drive System
Motor Mount Belt Align
LPT Cooling Tower - Drive Systems
The LPT Cooling Tower 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 cooling tower applications.
All LPT Cooling Tower models utilize heavy duty totally enclosed fan motors designed specifically for cooling tower applications. In addition to the standard motors offered on each cooling tower, EVAPCO offers many optional motors to meet your specific needs, including:
The belt drive system consists of multigrooved V-Belts with high lateral rigidity. The belts are designed for cooling tower service, and are constructed of neoprene with polyester cords. The belt drive is sized for 150 percent of the motor nameplate horsepower ensuring long durability and life.
Centrifugal Fans and Drives
The LPT 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 LPT 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.
Fan Shaft Bearings
The standard design of the EVAPCO LPT provides the customer with the easiest cooling tower to maintain in the industry. There are additional options which can make maintenance easier and extend the life of the cooling tower. These options are listed below.
LPT Cooling Tower - Unit Specifications
SECTION 23 65 00 - FACTORY-FABRICATED COOLING TOWERS
PART 1 - GENERAL
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, open circuit, forced draft counterflow cooling tower.
A. General. Submit the following:
1. Certified drawings of the cooling tower, 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 cooling tower thermal performance according to CTI Standard 201.
2.Test and certify cooling tower sound performance according to CTI ATC-128.
B. Meet or Exceed energy efficiency per ASHRAE 90.
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.
PART 2 - PRODUCTS
A. Manufactures: Subject to compliance with requirements, provide cooling towers 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, COUNTERFLOW COOLING TOWERS
A. Description: Factory assembled and tested, forced draft counterflow cooling tower complete with fill, fan(s), fan screens, accessories, and rigging supports.
B. Cooling Tower Characteristics and Capacities: Refer to the Cooling Tower 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 above the fan discharge during full speed operation in accordance with CTI Standard ATC-128.
D. Water Distribution System: Non-corrosive materials.
1. Evenly distribute of water over fill material with pressurized spray tree.
a. Pipes: Schedule 40 PVC, Non-corrosive Materials
b. Nozzles: Non-clogging, ABS Plastic, 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 for long life and durability (Optional Stainless Steel Water Touch Basin, Water Touch Unit, and All Stainless Steel Unit):
1. Removable stainless-steel strainer with openings smaller than nozzle orifices.
2. Joints: Bolted and sealed watertight.
3. Overflow, Makeup and Drain connections: Type 304 Stainless Steel (MPT).
4. Outlet Connection: Type 304 Beveled for weld and grooved for mechanical coupling.
G. Casing: Heavy Gauge G-235 Galvanized Steel or Type 304 Stainless Steel (Optional):
1. Casing panels shall totally encase the fill media to protect the fill from damage due to direct atmospheric exposure. 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. Fill Media: PVC; resistant to rot, decay and biological attack; formed, crossfluted bonded together for strength and durability in block format for easy removal and replacement; suitable for use as a working surface; self extinguishing with flame spread rating of 5 per ASTM E84-81a; able to withstand continuous operating temperature of 130°F; and fabricated, formed and installed by the manufacturer to ensure water breaks up into droplets.
I. Drift Eliminators: Same material as Fill. 0.001% drift rate.
J. Protective Air Inlet Screens: Galvanized Steel
K. Water Level Control: Brass mechanical makeup water valve and plastic float with an adjustable linkage.
2.4 MOTORS AND DRIVES
A. General requirements for motors are specified in Division 23 Section "Motors".
B. Enclosure Type: TEFC
C. Motor Speed: Single Speed (Option: VFD Duty, 2-speed)
D. Drive: Power Band Belt designed for 150% of the motor nameplate HP.
1. Belt: V-belt type.
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: 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: Aluminum, vertical complying with 29 CFR 1910.27.
2.6 SOUND ATTENUATION
A. Inlet Attenuation: Self supporting, 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.
LPT Cooling Tower - Sound Attenuation Packages
The standard LPT is the quietest, low profile centrifugal fan cooling tower in the industry. This is achieved by providing the first stage of inlet sound attenuation as part of the LPT ’s standard design. The LPT drive system, including the fan housing(s), electric motors, belts, bearings and drives, is completely enclosed by a protective housing which covers the drive system and also provides a significant level of sound reduction.
Reduces sound radiated through the end and side air intakes. 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 with minimal sound attenuation, a tapered discharge hood is available.