This case study details the works required by Technip to provide controlled air extraction from both spooler production lines within their Evanton spoolbase centre.

The Technip site is located at Evanton, Ross Shire.
The plant is provided by A-Mac Environmental and consists of four air extraction systems (two per production line).

Each system comprises of service bays (i.e. Autoracks or Workstations) each of which is provided with an air extraction hood and outlet dampers to the air extract ducting.
An air extract fan is located at each system duct exit which force ventilates air from the damper inlets to the building internal atmosphere via air filtration providing heat recovery.

Each production line consists of a pipe racking station followed by 8 welding bays. Air extraction is provided at each location and is divided into two separate extract systems as follows.

  • System 1: Racking and bays 1-4
  • System 2: Bays 5-8

Each fan/damper extract system operates independently of the other systems.

The project generally comprised of the following works:

  • Supply of a new Micrologix 1400 controller with expansion input/output and analogue output I/O cards.
  • Supply of an approved Functional Design Specification (this document).
  • Design, programming, testing and commissioning of the Micrologix 1400.


The current, kW and number of bays in use relationship to fan speed is illustrated below.


The energy saving feature of the system is clearly demonstrated when comparing the number of bays in use with the power consumed.

For example with 3 bays in use 3.5 kW are consumed per hour with the fan running at 90% of full speed (i.e. 45Hz), however in a conventional system the fan would be running at 100% (i.e. 50Hz) regardless which would consume 4.7 kW per hour. In this instance an energy efficiency saving of 26% will be realised.
The system will switch off bays as and when they are no longer required and following a short shutdown delay. When no bays are in use the system will run a longer shutdown delay and operate the fan at a minimum speed of 60% (i.e. 30Hz). In a conventional system the fan would be running at full speed and similarly an energy saving of 79% will be realised.


The system operation has been commissioned to achieve the required air extraction flow rates at the maximum possible energy efficiency.

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