At A Glance:
- Location : Chester, Cheshire
- Client: National Grid
- Consultant: Urban Water
- Contractor: Gunning Transmission & Distribution Services (GTDS) Ltd
Products Supplied:
- Models supplied: P006/2CSC/M
- Full retention separator design.
- Designed for the higher specific gravity of Midel or Synthetic Oil compared to Mineral Oil.
- Incorporates an actuated valve that closes when oil spill is triggered.
- 2 Chamber design as per National Grid approved specification.
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All products were supplied with tank shell specifications to suit the high ground water conditions created by the sites proximity to the sea.

This substation near Chester, Cheshire is one of the many new/refurbished substations that is transitioning to using a synthetic cooling oil for its transformers, such as Midel oil. The far
higher fire point of synthetic oils when compared to mineral oil dramatically reduces the fire risk on National Grid and similar substations and is therefore being widely adopted.
While the use of such a fluid reduces fire risk and associated costs, the difference in specific gravity (SG = 0.97 at 20°C) presents challenges for capturing this type of oil in a conventional separator in the event of an oil leak or spill. This has resulted in SPEL conducting extensive testing and redesign to ensure that Midel can be safely and reliably captured in the advanced SPEL Midel Separator. A further technical advance in the SPEL Midel Oil Separator is the inclusion of a motorised Automatic Closure Device (ACD) which will shut down in the event of a catastrophic spill.
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An alarm will sound and/or message an alarm on site or to a control room and automatically close off the separation chamber via the auto closing device, closed by a motorised valve. This is actuated by an oil alarm, closing the outlet in the case of a spillage emergency or when the maximum oil capacity has been reached.
The SPEL Midel oil separator still incorporates the SPEL coalescer which has been used and proven both in testing and in the real world for many years in the SPEL Puraceptor and Stormceptor ranges. The ‘heart’ of the separation process with its high volume coalescing material ensures optimum oil capture and minimum maintenance.