BS 4485-3:1988

Foreword
Committees responsible
Code of practice
1 Scope
2 Symbols and units
3 Thermal design principles
3.1 Cooling process
3.2 Heat transfer diagram for counterflow conditions
3.3 Crossflow tower calculation
3.4 Natural draught tower calculations
4 Types of cooling tower and their relative merits
4.1 General
4.2 Natural draught towers
4.3 Mechanical draught towers
5 Siting, spacing and environmental considerations
5.1 General
5.2 Siting
5.3 Spacing
5.4 Environmental considerations
6 Guidance on specified operational requirements
6.1 Selection of design conditions (including
      probability curves)
6.2 Guidance on the effect of variations of parameters
7 General thermal design
7.1 Packaging
7.2 Drift eliminators
7.3 Recirculation
7.4 Effect of altitude
8 Hydraulic requirements of cooling towers
8.1 Water distribution
8.2 Water losses
8.3 Cold water basin design
8.4 Water quality
8.5 Design for winter operation
8.6 Use of saline water
8.7 Effect of salinity on heat transfer
9 Mechanical equipment
9.1 Fans
9.2 Gearboxes
9.3 Drive shafts and couplings
9.4 Fan drivers
9.5 Supports for mechanical equipment
9.6 Vibration cut-out switches
9.7 Keys and keyways
10 Safety precautions
10.1 General
10.2 Mechanical plant
10.3 Electrical plant
10.4 Access
10.5 Fire precautions
11 Maintenance
Appendices
A Enquiry and suggested tender information for
      cooling towers
B Evaluation of noise in cooling towers
Tables
1 Symbols and units
2 Standard reference sheet for physical dimensions
3 Addition of decibels
4 Typical corrections to obtain octave band spectra
      for various fan types
5 Tower noise calculation
Figures
1 Air-water flow paths in crossflow, counterflow and
      mixed flow towers
2 Conditions of air and water in a cooling tower
3 Heat transfer diagram
4 Demand and characteristic curves
5 Performance curves for mechanical draught tower
6 Performance curves for natural draught tower
7 Illustrations of basic types of cooling tower
8 Spacing
9 Screen dry bulb and wet bulb isotherms for the UK
      for temperatures exceeded for the stated
      percentage of hours during June to September:
      period 1964-70
10 Mechanical draught counterflow tower: variation of
      tower size with cooling range, approach and wet
      bulb temperature
11 Natural draught tower: variation of duty factor
      with cooling range, approach and wet bulb
      temperature (at constant 70 % r.h.)
12 Natural draught tower: variation of base diameter
      with circulating water flow corrected for duty
      factor
13 Drift eliminators
14 Basic recirculation allowance
15 Correction for cooling range and approach at 17
      deg C wet bulb temperature
16 Effect of altitude on heat transfer diagram
17 Natural draught tower: water distribution
18 Mechanical draught tower: water distribution
19 Variation in evaporation losses with ambient
      conditions
20 Purge, make-up and evaporation quantity balance
21 Relation between purge ratio and concentration
      factor
22 Pond characteristic
23 Anti-icing arrangements
24 Effect of salinity on heat transfer diagram
25 Typical arrangement for induced draught fan
      assembly
26 Attenuation for distance from source
27 Directivity correction

Recommendations for the design of industrial and natural draught, and factory prefabricated towers.

This Part of BS 4485 gives recommendations for the thermal and functional design of industrial and natural draught water cooling towers and factory prefabricated cooling towers.

NOTE. The titles of the publications referred to in th is standard are listed on the inside back cover.