Explosion Venting for Gas Bottle Store at Glangwili General Hospital

January 2020

CS supplied three 1.22m x 2.44m explosion venting panels to Glangwili General Hospital for a new medical gas store within the hospital, offering testable, resettable explosion protection for the Hywel Dda University Health Board.
Full Case Study

In May 2016, the Estates Department of Carmarthenshire’s Hywel Dda University Health Board approached Construction Specialties (CS) for advice on the explosion venting requirements for a new gas bottle store being built at Glangwili General Hospital in Carmarthen.

Design Goals

The store was needed because bottles of Entonox (a mixture of nitrous oxide and oxygen, more commonly known as ‘gas and air’) have to be kept safe and secure, and be readily available for transfer to the wards.

Due to the nature of Entonox, which has to be stored at 10°C for 24 hours before use; an internal gas bottle store with heating was required, rather than an external cage located away from the building.

The new gas bottle store had to comply with the Department of Health’s Health Technical Memorandum 02-01: Medical gas pipeline systems Part B: Operational management, which states construction materials that must be used and requirements for explosion venting:

“Blow-out panels should be fitted into the external wall of any ground level store constructed as part of, and under, another building. These panels should be sited at a minimum height of 2.3 m above ground level.”

Carmarthenshire’s Hywel Dda University Health Board approached CS after deciding that, for peace of mind, a testable, re-settable explosion venting system was preferred, providing a system that would operate as intended in the event of an explosion, or over pressure, within the store.


Based on the building volume, Construction Specialties recommended using three 1.22m x 2.44m Explovent ERP-IC panels based on the building volume, giving a total venting area of just under 9m2.

CS Explovent is a hinged panel explosion venting system that allows testing and resetting as part of regular maintenance regimes, to ensure panels are functioning correctly.

Explovent panels are engineered and factory-calibrated to release at very low design pressures (between 0.0072bar and 0.02 bar). When internal pressures rapidly rise, the panels release quickly and, once pressure has been relieved, return to a near-closed position. They remain held slightly open to allow air to return to the room, protecting the structure from implosion forces as super-heated gases begin to cool.

The panels are made of insulated aluminium, mounted in an aluminium frame, and can be fitted in portrait or landscape orientation, in sizes of up to 1.22m by 2.44m. They have a durable fluorocarbon polymeric coating, or can be supplied as a high strength translucent polycarbonate panel insert, to reduce the need for artificial lighting. Smooth bevelled surfaces reduce dust accumulation and allow easy cleaning.

The new store was built by Swansea-based contractor Edmunds Webster next to and underneath one of the hospital buildings. Construction of the new gas store was completed in December 2016.