EVAPCO LPT Low Profile Centrifugal Fan Cooling Tower

A compact, quiet tower for rooftops with a height limit

The EVAPCO LPT is the smaller, low-profile member of EVAPCO’s forced draft centrifugal fan cooling tower family. It is a single-cell, factory assembled, counterflow open tower rated by EVAPCO from 27 to 333 nominal tons, and it is intended for places where overall height, fan noise or an indoor, ducted arrangement rule out an axial fan tower. EVAPCO describes it as the quietest low-profile centrifugal fan tower in its range, because the first stage of inlet sound attenuation is part of the standard design.

In operation the process water is pumped to a pressurized spray system on top of the PVC fill while the centrifugal fan or fans blow air upward through the fill from the base. Part of the water evaporates, the remaining water cools and drains into the basin, and the saturated air leaves vertically through the top. The drive system, meaning motor, belts, bearings and fans, is enclosed in a protective housing that also reduces sound.

Open towers of this kind are generally used to reject condenser water heat from chillers and process loads. Because the process water is exposed to the air, dirt and impurities can enter the loop, so a bleed line, a strainer and a suitable water treatment programme are part of the system design; where the fluid must stay clean, a closed circuit cooler or a heat exchanger between the tower and the process is the usual alternative.

Technical specifications

Model range and engineering data

LPT models are arranged in footprint groups of about 3 x 6, 5 x 6, 5 x 9, 5 x 12, 8 x 9 and 8 x 12 feet as shown by the printed basin heater and support tables (footprint reading derived, confirm on certified drawings). Each group offers several motor sizes so the fan power can follow the selection. Selected printed rows:

As in the LSTE series, an adequately sized bleed line must be installed, and for external static pressure up to one half inch the next larger fan motor should be selected. Catalog drawings are not certified prints.

Sound, winter and maintenance options

Where the standard sound level is still too high, EVAPCO lists fan side inlet attenuation, end and side inlet attenuation, and straight sided or tapered discharge attenuation, with factory certified sound data supplied for each option. The inlet attenuator extends the external belt adjustment so the belt can be tightened without entering the unit. Solid bottom panels are included with that option to force the air through the attenuator.

For idle periods below freezing the bulletin gives electric basin heater sizes by footprint: for the 3 x 6 ft unit one 2 kW heater at 0 F, 3 kW at minus 20 F and 4 kW at minus 40 F, and for the 8 x 12 ft unit 9, 12 and 16 kW. A remote sump or pan hot water coils are the alternatives. Other options printed include stainless steel construction, an electric water level control, vertical ladders and a vibration cutout switch.

The unit sits on structural steel beams under the outer flanges for the full length, levelled to within 1/360 of unit length. Water treatment can be added using the Smart Shield or Pulse-Pure systems described by EVAPCO.

Using the LPT in Oman and the GCC

Low-profile towers are used in the region on rooftops of hotels, offices, hospitals, malls and residential buildings where height is limited by architecture or authority rules, and where low sound is needed near occupied areas. Selection must be made at the project’s design wet-bulb temperature, which can be high in coastal summer conditions, rather than at a catalogue standard condition, otherwise the tower may not deliver the required cooling on the hottest days.

Make-up water in the region may be desalinated water, groundwater with high dissolved solids or treated effluent, and each needs a suitable water treatment programme, blowdown control and regular cleaning, together with a Legionella control plan. Dust and sand enter towers easily, so basins and strainers should be cleaned at regular intervals, and side-stream filtration can help reduce fouling. Check the structural support for the operating weight, including water, and leave access space for maintenance.

Information to send with an enquiry

• Heat load, flow rate and inlet and outlet water temperatures
• Design wet-bulb temperature
• Height and footprint limits
• Sound limits and quantity

Documents and quotation

The attached engineering data covers the LPT dimension tables, weights, connection sizes and optional equipment together with the LSTE series. Seven Star LLC is an independent supplier in Muscat. To request a quotation, send the water flow, hot and cold water temperatures, design wet bulb and the available footprint and height. Related products are listed under cooling equipment.