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Sensor gets the call

Sensor Technologies was recently awarded phase 4 of the Vodacom Midrand office park for fire detection and fire protection installations.

This latest order cements Sensor Technologies long running relationship with Vodacom. Beginning in March 1998 Sensor Technologies was awarded a R67 000 smoke detection installation for the Vodaworld building.

Projects followed at Parkfields Pretoria; Florida; Germiston; Meyerton; Persequor Park Pretoria; and Centurion.

All of the buildings are computerised switching centres that are fitted with conventional fire detection systems operating in a 'double knock' mode and activating automatic gas extinguishing systems both in the room, floor and ceiling voids.

Phase 4

Phase 4 Midrand project follows a R2 million installation in the Corporate Park building, a R1,2 million installation in the service provider building and an R822 000 project in the customer care building.

The phase 4 contract was won on tender against stiff opposition and will consist of a fully addressable fire detection system installed throughout the premises interfaced to a conventional smoke detector installation in the computer room areas operating a fully automatic gas extinguishing system.

This project, as with all the other buildings, will be fitted with the latest Aritech FP2000 analog addressable fire panel of four loops and 64 zones, interfaced to over 300 Apollo addressable smoke sensors and interface units.

Apollo smoke sensors are of the optical type, which sense smoke particles entering the sensing chamber and scattering the light source. On operation the Aritech panel identifies the exact sensor and identifies it on the LCD display by line number, device number and provides a text message of location eg Mr Smith's office.

Phase 4 comprises:

7 x Aritech addressable fire panels

3 x Remrad radio signalling systems

3 x Vesda scanner units

2000 x Smoke sensors

304 x Argonite gas cylinders

Fire panel

This highly sophisticated fire alarm system also provides Vodacom with the following features:

* One man maintenance.

* Maintenance warning when devices require cleaning.

* On-line diagnostics.

* Day/night sensitivity adjustment.

* Coincidence facility.

* Start-up default mode which then automatically configures and checks devices on the lines.

User friendly

In addition to a comprehensive zone and general information LED array, the panel features a generous 8 x 40 character graphic LCD display. This display provides every single address with up to 80 characters of site-related alphanumeric information. Furthermore, it can visualise graphically the performance of any one sensor on a zone-per-zone basis.

Information such as: realtime value, test value, average value, highest value, lowest value and communication quality and contamination is clearly represented in the form of a bar chart. The above can also be plotted for any single sensor.

False alarms

Several mechanisms to prevent false alarms are provided such as:

* Floating background with automatic level compensation.

* Day/night sensitivity setting for industrial sites and a coincidence mode within and in between zones.

* A soak test facility which follows-up 'suspect' sensors further enhances false alarm immunity.

Maintenance friendly

Maintenance warning is generated whenever one or more detector contamination level is reached. The availability of realtime diagnostics and statistics per sensor offer an in-depth information, all visualised as described above, locally or by remote dial-up. A service reminder signal can be generated at the time and date of the next planned maintenance. The physical checking of sensors can be performed simultaneously by up to four engineers without anyone attending the panel.

Although not used at Vodacom the system provides for networking over a copper or fibre network. As the Vodacom buildings are all fitted with their own independent control rooms interpanel networking is not required.

Each building on the premises is fitted with its own Remrad radio signalling system direct to the municipal fire department. In the computer areas at Phase 4, service provider building and customer care building, the rooms are monitored by the Vesda smoke aspriration system.

This provides a very early warning of smoke conditions alarming the building operators of problems before any visual indication of smoke can be seen.

With the installation of a PVC pipe network both in the floor voids and ceiling space connected to the Vesda control unit, smoke is drawn through strategically drilled holes in the pipe and sampled over a laser beam. This highly sensitive means of smoke detection provides alarms at a level as sensitive as 0,05% obscuration per metre.

Gas protection

All gas-extinguishing systems consist of Argonite gas. Manufactured by Ginge Kerr in Denmark and approved by international bodies, Argonite extinguishes fires cleanly with no risk to human beings, equipment or the environment. Argonite consists of a mix of 50% Argon and 50% Nitrogen and works by reducing the oxygen content in the room to approximately 12,5% at which point most fires are extinguished but humans can continue to breathe.

For further details contact Keith Norgate, Sensor Technologies on tel: 011 452 1339.

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