A siren's song
Published: 01 September, 2006
MEDC has been designing and manufacturing alarm, signal, control and communications equipment since 1975. Over the years the company has specialised in a range of products designed for harsh environments and where there is a risk of explosion due to the presence of flammable atmospheres both offshore and onshore.
The company has pioneered the use of Glass Reinforced Polyester (GRP) in explosion-proof products. GRP has several advantages over other materials - a lower capital cost combined with minimal maintenance and extended lifetime lowers the cost of ownership.
This is why MEDC decided to extend the range of uncertified (safe area) equipment for use in harsh industrial and marine environments.
Spokesman, Daniel Close explained that MEDC’s GRP range includes manual call points, status lamps, beacons and strobes, sounders and horns, alarm bells, speakers, control units, control stations and panels, junction boxes, terminal boxes, distribution panels and boards.
All MEDC’s products are available in a range of certifications including ATEX, UL, CSA and GOST. A wide variety of these products are held in stock for despatch within 24-hours of ordering. The company also offers the Next 2 range of loudspeakers for safe areas or interiors.
Daniel explains: “For instance with our sounders, we offer a standard range with many options that is completely customer specified. We can also take on very special orders and develop a completely bespoke product for our customer. If a customer needs specific tones, sounds and patterns, then we can program them. We also offer the DB3V, which is a standard sounder but it is also possible to put recorded messages on it.”
The beacons and strobes MEDC manufactures are certified and regarded as suitable for use in areas where lightness in weight combined with corrosion-resistance and strength are required. The beacons are available in LED, Xenon and in a rotating beacon/sounder combination and, of course, the company offers steady beacons.
MEDC is producing lightweight, flameproof sounders for extremely hostile surroundings. Outputs of 103dB(A) and to 118dB(A) at 1m are available.
Recently the company launched a new range which offers up to 20 seconds of speech which can be recorded via an integral microphone or an input from an external source. The unit incorporates a variable delay allowing speech to be repeated at equal intervals of up to approximately 15 seconds. In addition to all this, clients can also choose explosion-proof loudspeakers for use in potentially explosive gas & dust atmospheres. These can use MEDC Proprietal GRP technology to offer a cost effective robust and corrosion free-solution to metal loudspeakers. With power ratings up to 25W this range is suitable for PA and VA applications.
“As well as making sounders and beacons, we can also manufacture control panels. We deliver our products to all the major alarm and extinguishing system manufacturers in the world, such as Tyco and Honeywell,” he concludes.
Asserta range
MEDC’s sister company, Fulleon introduced the Asserta alarm sounders and beacons range. This is a range of extremely robust, high output products suitable for use in exposed operating conditions which require protection to IP66.
Asserta incorporates innovative design features to provide significant benefits for the user and installer alike, says the company.
Marketing manager Bob Choppen explains that the sounders offer a first and second fix facility; terminals in the shallow bases provide easy access for cabling and lightweight ease of handling during installation. The horn and electronics can be offered up to the base and final connections made with a simple plug and socket connection. Even the horn assembly is designed to remain in-place before the fixing screws are tightened to allow maximum safety during installation.
“The combined beacon sounder versions have been designed as an integrated, aesthetically-pleasing assembly, the asymmetric beacon configured to make optimum use of the flash energy by directing it towards observers rather than merely allowing general scatter,” he reports.
The beacon is also available separately with a dedicated trapezoidal base, again the lens format allows for best use of the beacon’s light output by optimising directivity,” he reports.
For maximum flexibility the sounders and beacons are available for operation on low voltage AC/DC or AC mains voltage, so only two versions are needed to cover all common supply voltage, minimising stocking decisions.
The range has nominal outputs of 110dB(A) or 120dB(A), the acoustic and electronic designs having been optimised for maximum efficiency, to minimise loads on power supply equipment.
The Asserta 110 & 120 can both be configured to produce voice messages as well as having a choice of 42 alarm tones, which cover most of the signals likely to be used worldwide. Additionally, three alarm stages can be used where a number of warning levels have to be communicated.
The Asserta Midi is a simpler sounder, but no less robust, and caters for applications where complex functionality is not the prime objective. It does offer wide range operating voltages so that it can be used in the majority of plant and process environments.
Bob concludes: “Mounting brackets are available to enable the sounders be positioned for optimum performance and sound distribution, a feature usually only available for pure horn designs.”
Bells, buzzers and hooters
Klaxon Signals Limited manufactures and supplies the world’s largest range of sound signalling equipment. The company’s extensive product range includes: electronic sounders; fire alarms; sirens; beacons; bells; buzzers and hooters. Recently the company won a major contract with BCD to supply their Sonos sounder-beacon to Birmingham’s National Indoor Arena.
“The Sonos sounder-beacon uses LEDs as its light source, drawing significantly less current than traditional xenon beacons without a loss of light output. A translucent sounder case enables greater light spread for more effective warning. Additionally, the unique Timesaver Base, which allows the sounder-beacon head to simply twist and click into place, ensures fast and reliable installation. A removable tab on the unit base means that the head can be locked into place when commissioning is complete; no locking is required,” explains marketing manager Kristian Johnson.
Sonos was certified by the Loss Prevention Certification Board (LPCB) in 2005 and is also compliant with the DDA.
Richard Davies, Klaxon’s Divisional Sales Manager, remarked: “Klaxon won the contract to supply the fire alarm sounder-beacon units for the NIA project based on the company’s ability to deliver a product which met the required specification in full. The Sonos product offers ease of installation, can be used in retrofit applications and provides both audio and visual warning, thus following DDA guidelines.”
The current consumption of the sounder-beacon unit also has a significant impact on the fire alarm system design. Being able to achieve high sound output coupled with a good visual warning helps the Sonos sounder-beacon unit to limit the size of the power supply and battery back-up.
Approximately 300 deep-base IP65-rated Sonos sounder-beacon units were installed in the NIA’s two main car parks. The system upgrade work also included new conventional fire alarm sounder circuits controlled by analogue/addressable sounder circuit controllers supported by local power supply units, complete with battery back-up. The existing fire alarm system was re-configured with additional networked control panels and repeater panels being added.
What made the installation particularly difficult was that the upgrade had to be undertaken around the programme of events scheduled for the NIA to avoid any disruption.
Installation is now complete in both of the car parks, with work nearing completion on the other buildings. Once finished, BCD will carry out a full programme of testing and commissioning before proving to the client that the system is fully operational and complies fully with the specification laid down at tender stage. Upon satisfactory completion and handover to the client, the NIA will be issued with operating manuals and a system log book along with the necessary certificates required as part of BS 5839-Part 1:2002, Fire Detection and Alarm Systems for Buildings. Training sessions on the system’s operation as well as British Standard responsibilities are offered as part of the BDS service agreement.
