• System Design

      Mihir Cooling Towers are constructed of the Industry’s most durable materials and are designed for superior performance providing long, trouble-free operation. Nevertheless, proper equipment selection, installation and maintenance are the basis in guaranteeing optimum performance. Several of the key considerations when designing, installing and operating a cooling tower are presented below.

    • Air Circulation

      The location of a cooling tower is extremely critical when reviewing system design. Since cooling towers consume large quantities of air, proper spacing is required for the tower to perform properly. The best place to install any cooling tower is on a roof or at ground level away from walls and obstructions. Cooling towers that are located near walls, wells, and enclosures or are flanking high walls must be properly located in order to prohibit the effects of recirculation. Recirculation occurs when some of the hot, moisture-laden air leaving the cooling tower is introduced back into the fresh air inlets. Recirculation results in the breitling copy inlet wet bulb temperature to be increased causing the capacity of the cooling tower to be significantly reduced. In short, the designer must take care to provide generous air inlet paths.

    • Maintaining System Cleanliness

      A cooling tower removes heat by evaporating a portion of the recirculated spray water. As a general rule, a cooling tower evaporates 3 US GPM per 100 Tons of cooling capacity. As this water evaporates, it leaves behind all of its mineral content and impurities. For that reason, it is essential to blowdown (bleed) an amount equal to that which is evaporated to prevent buildup of impurities. It is very important to provide make up water to replace the water that is both evaporated and bled from the tower system. Make up water should be equal to both evaporation and bleed. (Make up water = Evaporation rate in GPM + Bleed rate in GPM). If adequate blowdown is not maintained, the mineral content in the water will increase until solids eventually deposit and coat the heat transfer surfaces of the unit, causing heavy scaling. Therefore, the blowdown line should be installed in the external piping of the unit. It must be properly sized for the application and be provided with a metering valve and flow measurement device to allow for field adjustment of blowdown rate.

    • Water Treatment

      To control the buildup of dissolved solids resulting from water evaporation, as well as airborne impurities and biological contaminants including Legionella, an effective and consistent water program is required. Simple blow down may be sufficient to control scale, but biological contamination can only be controlled with biocides. Any chemical water treatment used must be compatible with the tower’s materials of construction. Ideally, the pH of the circulating water should fall between 6.5 and 9.0. Batch feeding of chemicals directly into the cooling tower is not a good practice since localized damage to the tower is possible.

    • Capacity Control

       Since the design wet bulb temperature for which a cooling tower is sized occurs only a small percentage of the time, and cooling tower loads tend to be dynamic, some form of capacity control should be employed. Cycling the fan on and off performs the most common form of capacity control. However, this manner of control may result in large temperature differentials and does not provide close control of the leaving water temperature.

      Improved methods of capacity control can be better realized through the employment of VFD drives. VFD Drives are an excellent method of maximizing dynamicload- control while reducing operating costs. Simply put, VFD Drives provide a complete range of capacity control.

      Multiple cell units will provide additional steps of capacity control resulting in substantial reduction in energy costs.

    • Piping

      Cooling tower piping should be designed and installed by professionals who adhere to standard engineering practices. All piping must be supported by properly engineered hangers and supports with allowances made for possible expansion and contraction of the piping system. NO external loads should be positioned on the cooling tower connections. DO NOT anchor any of the piping supports to the cooling tower or its framework. Horizontal pipes located above the tower operating level should be short as possible, as it can cause possible overflow during tower shut down and/or air pockets upon startup.

    • Managing Biological Contamination

      Water quality MUST be checked regularly for biological contamination. If biological contamination is present, a more aggressive water treatment and mechanical cleaning program must be replica watches carried out. The water treatment program should be executed by a qualified water treatment organization. It is important to keep all internal surfaces of the cooling tower clean.

    • CAUTION!

      The cooling tower must be located at such distance and direction to prevent the possibility of contaminated tower discharge air being drawn into building fresh air intake ducts. The purchaser of the cooling tower should employ the services of a Licensed Professional Engineer or Registered Architect to certify that the location of the tower is in compliance with the applicable air pollution, fire and clean air codes.

    • Chilled Water Systems

      Tons = (GPM x ∆T) / 24

      1 Ton = 12,000 BTU/Hr

      Standard flow rate = 2.4 GPM per Ton (10F ∆T)

      Required flow rate for molds = 4.8 GPM per Ton (5F ∆T)

    • Cooling Tower Systems

      Tons = (GPM x ∆T) / 30

      1 Ton = 15,000 BTU/Hr

      Standard Flow Rate = 3.0 GPM per Ton (10F ∆T)

    • Commonly Used Formulas

      Ft3 x 7.48 = Gallons

      Gallons (H2O) x 8.33 = Lbs.

      Feet of Head / 2.31 = PSI

      KW x 3,413 = BTU/Hr.

      KW = (Running Amps x Volts x 0.85 x 1.73) / 1,000

      KW x 1.342 = HP

      HP x 2,544 = BTU/Hr

      BTU/Hr = GPM x ∆T x 500 (water)

    • Plastics

      Injection Molding
      HDPE 30#/Hr = 1 Ton
      LDPE, PP, Acrylic 35#/Hr = 1 Ton
      Nylon, PPO, Urethane 40#/Hr = 1 Ton
      PET 45#/Hr = 1 Ton
      ABS, PS, Acetal 50#/Hr = 1 Ton
      PVC 75#/Hr = 1 Ton
      Hot Runners 1 kW = .15 Ton
      HDPE, LDPE, PP 50#/Hr = 1 Ton
      PS 75#/Hr = 1 Ton
      PVC 80#/Hr = 1 Ton
      Blow Moulding
      All Resins  40#/Hr = 1 Ton
      Hydraulics 1 HP = .1 Ton
      Feed Throats 1/2 Ton Each
      Gear Boxes 1 Ton Each
      Temp. Control Unit Pumps 1 HP = .2 Ton
      Screws and Barrels 1 Ton per inch of Screw Dia
      Other General
      Air Compressors w/Aftercoolers 1 HP = .2 Ton
      Compressed Air Dryers 1 HP = 1 Ton
      Vacuum Pumps 1 HP = .1 Ton
      Machine Tools 1 HP = .1 Ton
      Transformers 100 kVA = .9 Ton
      Welders 0.25 Ton per Tip
      Water Cooled Air Cond. or Chillers 1 Twr Ton per Ton
      Hydraulic Pumps 1 HP = .1 Ton
      Die Casting
      Zinc 125#/Hr = 1 Ton
      Aluminum 35#/Hr = 1 Ton
      Plating Baths
      Tons = D.C. Amps x D.C. Volts x 0.00017


    Lowering of Cooling capacity
    Motor stoppage
    1. Electric blackout
    2. Fuse burnout due to damaged Contacts
    3. Insufficient switch capacity
    4. Bad switch contact
    1. Contact power company
    2. Get proper fuse
    3. Change to proper switch
    4. Adjust / Clean Contacts.
    Sudden lowering of motor speed(rotations per minute)
    1. Defective starter
    2. Too heavy load
    3. Low supply voltage
    1. Check starter for defects
    2. Reduce the load by checking motor current
    3. Consult power company
    Cannot rev up motor speed (rotations per minute)
    1. Defective starter / starter connections
    2. Connection of rotary and fixed section
    3. Motor winding damaged
    1. a. Correct connection according to name plate
      b. Check supply voltage across all 3 phases
      c. Check current in all 3 phases
    2. Send out to repair shop
    3. Send out to repair shop
    Fan Stoppage
    1. Jammed Bearing
    1. Replace bearing
    Temperature rise
    Motor getting over heated
    1. Too heavy load
    2. a Lowering of voltage supply
      b Unbalanced voltage supply
    3. Contact between rotary and fixed section
    1. Lighten load proper level
    2. a Consult power company
      b Consult power company
    3. Change bearing or supplement grease
    Rise in water temperature
    Rise in water emperature
    1. Water flow above specified flow
    2. Air flow below specified flow
    3. Load higher than design
    4. Fill checked or coated
    5. Fresh air intake not sufficient or area sufficient or area around tower not as specified.
    6. WBT high
    1. Regulate to correct flow rate.
    2. Adjust blade angle check and clean jali.
    3. Adjust load to correct level.
    4. Clean / replace fills. Use proper water (Makeup)quality
    5. Improve ventilation and ensure exhaust air does not get recycled.
    6. Check design condition and ensure no recycling of exhaust air.
    Water flow Less
    Water flow Less
    1. Filter chocked
    2. Sprinkler pipes chocked
    3. Level of water low in pump
    4. Pump small
    1. Clean water filter.
    2. Clean pipes and holes
    3. Adjust float/ inlet flow ensure proper make-up
    4. Replace for correct flow volume
    Air flow low
    Air flow low
    1. Fan speed low
    2. Fan blade angle incorrect
    1. Check bearings/motor
    2. Correct blade angle to required setting
    Noise & Vibration
    Noise & Vibration
    1. Fan mounting loose
    2. Fan blocks loose
    3. Fan unbalanced
    4. Motor bearing faulty
    5. Many parts rubbing against tower components
    1. Tighten mounting bolt and correct/ replace if needed.
    2. Tighten blade in hub
    3. Rebalance and adjust
    4. Check and grease or replace bearing on motor.
    5. Give proper clearances and adjust/ align components
    Water carry over
    Water carry over
    • For Round Bottle Tower
      Fan mounting loose
    • For Rectangular Tower
      Certain Nozzles chocked
      Some Nozzles may not be vertically downward
    1. Inlet water pressure high
    2. Blocking of fills


    • Adjust sprinkler angle as to match the specified rotation
    • Clean Nozzles
      Reinstall Nozzles vertically downward
    1. Reduce water pressure
    2. Clean up any blocked part or change