Air Cooled Heat Exchangers


Air cooled heat exchangers provide reliable cooling to liquids and gases in hot and dry climates where cooling water is limited. We design each unit to perform based on the worst potential ambient temperature and always provide the correct outlet temperature.

Oil & Gas Extraction

Fin Fan Coolers rapidly reduce the temperature of fluid in the producing train in preparation for further processing.

Power Generation

Air Blast Coolers work to condense steam from a gas to a liquid to be reused in the energy process. Alternatively, the coolers can reduce the temperature of water in preparation for disposal.

Process Cooling

Air Cooled Heat Exchangers effectively reduce the temperature of process fluid for use in manufacturing processes.

Oil, Gas and Chemical Works

Our coolers have a long service life and work in any environment. Our coolers are in action in refineries and chemical manufacturing works across the world.



Forced draft fin fan coolers push air from the the bottom of the unit, underneath the tube bundle, through the finned tube and out of the top. Forced draft coolers provide excellent cooling efficiency at a reduced cost in comparison with induced draft coolers. 
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Induced draft coolers pull air from the bottom of the cooler through the tube bundle and out of the top. This design provides excellent temperature control and more even cooling around the entire surface area of the tube bundle. In addition to this it also protects the finned tube from the elements. The downside of these advantages is a higher operating and manufacturing cost. 
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Spiro-Gills Thermal Products Ltd: Air Coolers and Heat Exchangers for use in oil refineries, petrochemical plants, power generating stations, and fertilizer and gas production plants throughout the world.

Spiro-Gills’ over 70 years experience in the design and manufacture of air coolers and heat exchangers means that our highly trained and experienced thermal design engineers are able to offer a bespoke solution to our customers in the design of their induced draft air coolers or forced draft air coolers and heat exchangers, both thermally and mechanically.

Spiro-Gills Thermal Products Ltd makes use of leading-edge computer equipment, including the latest Computer Aided Design systems, to ensure maximum efficiency in:
  • Thermal design
  • Mechanical design of headers and steel structure
  • Noise level predictions
  • Preparation of the specification sheet
  • Preparation of the general outline drawings
  • Preparation of proposals
  • Price estimation

ACHE Design Considerations


The plug header is the most commonly used header type for working pressures up to 350 bar in heat exchangers and air coolers. The plughole opposite each tube allows the finned tube to be expanded into the tube sheet. It also facilitates mechanical cleaning and plugging in case of leakage repairs, re-tubing and upgrading.

For hydrogen service at high pressure, seal welding or strength welding can be provided. This is less expensive than using pipe headers, which are generally employed with a service pressure above 200 bar.


The cover plate header is used for fluids with high fouling factors up to 40 bar maximum where frequent mechanical cleaning is needed. It is also used for highly corrosive process fluids to allow periodic checking of the corrosion allowance.

For full specifications please download our brochure

Tube Material

Stainless Steel, Galvanised Steel or Metal Alloy Tubes provide varying effectiveness based on the cooling requirement of the process fluid.

Fin Material

Aluminium, Copper and other metal alloys dissipate heat based on their thermal conductivity. 

Fin Design

There are four main applied fin styles. Each has advantages in regards to heat transfer and thermal efficiency.

Fan blades

Variable frequency motors have done away, for the most part, with variable pitch fan blades. Each application is different and for this reason the choosing the correct fan blade is critical. Spiro Gills uses the latest HTRI software to determine the correct blade design for every cooler.

Belt and pulley

Belt and pulley transmissions are used for up to 37kW. Pulleys are dynamically balanced. Belt types are:

• V belt
• Toothed belt (HTD)
• ChevronBelts

Gear drives

Gear drives are generally preferred for over 37kW and are:

• Parallel shaft
• Right-angle drive

Electric motors

Electric motors are generally used as drivers, being selected to satisfy clients specific hazardous area requirements when required. Hydraulic motors may also be used, as well as low-speed direct-drive electric motors.


Airflow can be controlled in one of the following ways:

• Variable-speed electric motors (variable frequency)
• Louvres (manual or automatic)
• Two-speed electric motors
• Automatic variable pitch fan


Spiro Gills has recently purchased a large Dugard CNC machine to for machining headers. This video shows a plug style header being manufactured at Spiro Gills factory in Stoke On Trent.


If you would like more information on any of the services we offer or have any queries then please do not hesitate to contact us.



    Spiro-Gills Thermal Products Ltd
    St Albans Road
    ST16 3DR
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