Taking control of fire safety

The MRI first began in 1752 as a small house in Withy Grove. It is now a major complex based on Oxford Road, not far from the city centre, specialising in many areas including emergency services, renal medicine and transplantation, cardiology and cardiothoracic surgery, orthopaedics and intensive care. The MRI is also a major teaching hospital and is situated next to the campus of the Manchester Medical School and Manchester University.  The bed complement of 686 caters for acute surgical and medical services to the city and surrounding regional area.

Major development

The recent refurbishment has meant significant development of the site’s fire detection and alarm (FD&A) system. The system extension in the newly renovated building is massive, employing 90 of the company’s state-of-the-art Algo-Tec 6400 fire sensor control panels and a staggering 170 kilometres of cabling. The Protec Algo-Tec 6400 is a fully distributed, networked interactive digital addressable fire detection and alarm system, ideally suited for large sized buildings such as those at the MRI.

Designed and manufactured by Protec to comply with EN54 parts 2 & 4 1998, the system architecture has been developed to provide a seamless network of display and control nodes and loop processing nodes that can be located to suit the site structure and for wiring convenience. Around 17,700 loop devices are utilised here, including detectors, sounders and beacons, call points and a number of dedicated interfaces unique to Protec, some of which allow innovative design features which have cut project costs considerably by removing unnecessary system duplication and reduced hardware requirements considerably.

To manage and oversee the whole system, the 90 control panel nodes are connected by a site wide network infrastructure loop, linking each independently controlled hospital building to two head end locations, one in the telephone exchange, and the other in the security building. Both of the panels used here are fully functional yet provide backup to each other, but perhaps most interestingly have an interface that allows analysis of system device data, operation of ancillaries and other specific control functions by means of a user-friendly graphics interface displayed on a standard PC.

This primarily serves two purposes; the management of the fire alarm system and management of the smoke dampers across the whole site. The information is displayed in a simple to read, illustrative style and allows operators to focus down to the detail of individual fire alarm devices and smoke dampers.

Keeping control

One of the most interesting of the interfaces used at the MRI has been designed by Protec to allow the FD&A system itself to provide the management of the 1,100 smoke dampers over the FD&A system loop, obviating the need for the independent system that previously would have been required. Even the power supply to the dampers, typically supplied by individual 240 volt spurs (one for each damper) is eliminated by this arrangement, being replaced by Protec 24 volt battery chargers, each of which provides power to around 20 dampers. There is also an associated cost saving in hardware like cabling, distribution boards, and separate management control panels that are now no longer required.

As a result, a saving of between £200 and £300 is estimated for each damper on site. There is also a logic switching interface that detects the switched state of the associated critical dampers, closing them when necessary to prevent dangerous pressure build up within the air handling unit plant (AHU).

The fixed sprinkler system is also managed by means of the FD&A loop, monitoring flow switch, isolator valve and pump signalling, and thus eliminating the need for separate wiring and management systems. This permits water flow within the sprinkler system to be detected and shown on the FD&A control panel as a fire event.

Seamless integration

The new hospital buildings recently commissioned are of course not the only ones on the huge MRI complex. Existing buildings are still in use and still use their original FD&A systems from a variety of different manufacturers. All of these have been seamlessly integrated into the new scheme by another Protec interface that brings signalling into the new main network infrastructure

The main hospital building houses three hospitals and these were required to be delivered in four phased handovers with staff and patients populating each commissioned phase at different times. The fire alarm loop and network wiring was configured to facilitate each phased handover and Protec had to find a way to test and prove the cause and effect scenarios, across construction phases, before staff and patients moved in.

To do this, the company developed a small hand held input injector which connects to the stand alone network; this unit accurately simulated the inputs from the adjacent networks allowing the testing of cross network cause and effect without other hospital networks being connected.

Similarly the proving and demonstrations of the smoke damper status and their individual override commands was achieved in graphical format by connecting a laptop computer to the individual networks.

This allowed the Heart and Renal Unit to be commissioned first, followed by the Children’s hospital two years later, then the Women’s hospital and finally the Adult Hospital. These testing procedures had direct benefit to the hospital that once the independent networks had been integrated into one, only minor cause and effect proving tests were then required to be carried out, minimising any patient disruption.

Air sampling

There are four large atrium areas in the MRI hospitals, all protected by beam detectors because localised point source detectors lack the widespread coverage necessary for rapid response to fire situations in such places. One problem, however, associated with beam detectors can result from the physics of the airflow in atria. Due to the large volumes of air present, rising warm air often causes stratification, and a thermal barrier forms towards the top of the air column, preventing the flow of smoke particles and other gases from reaching the optical beam. At the MRI, Protec overcame this limitation by using additional Cirrus Pro aspirating detectors within the Children’s hospital atria. Cirrus Pro actively samples the air for signs of the ionisation products of combustion. These ionised particles are minute and easily pass through the thermal barrier, and are then detected by the cloud chamber at the heart of Cirrus.

Site Project Manager for the MRI, Bryan Mawn, thinks that the many innovations provided by the Protec FD&A system, including the sophisticated engineering proposals provided at the tender stage of the project, were responsible for the company being appointed to provide the fire safety system for the project. “Savings generated from eliminating the now un-necessary duplicate operating systems for the smoke dampers alone may have amounted to over £1/4m for a project of this size.”

The Manchester New Hospitals Development on the site of the Manchester Royal Infirmary is the largest single healthcare investment ever in Greater Manchester. The scheme has created five new state-of-the-art hospitals: Women’s, Eye, Adult, Children’s and new provision for Mental Health users.