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Incorrect sprinkler head positioning (top) compared to correct sprinkler positioning (right)

Incorrect sprinkler head positioning (top) compared to correct sprinkler positioning (right)



Sprinkler issues in false ceilings

Simon Ouellette, engineering services supervisor, Victaulic, discusses fire protection issues in false ceilings, the safety threats and technological solutions

September 2014

Suspended ceilings are frequently found in high-end hotels, auditoriums, shopping centres and a range of other commercial and industrial buildings. They are popular with engineers and architects because they offer a low-cost, easy-to-install solution to help hide fittings such as electrical boxes and heating, ventilation and air-conditioning systems from plain sight.

Originally developed to hide the underside of the floor above and to provide sound attenuation within a room, they generally consist of grids suspended from concrete ceilings by wires and holding a variety of tiles and light fittings.

Since their widespread adoption in the 1960s, the integration of fire protection with suspended ceilings has proved problematic, as hard piping systems have been unable to handle the full range of challenges they present. Proper sprinkler head positioning with the ceiling surface is a significant safety issue that is often overlooked.

 

Thanks to their innate flexible nature, from which they derive their key attributes and benefits, suspended ceilings are prone to settlement, and move after installation through the course of time – and especially in areas of seismic activity.  Additionally, suspended ceilings will move if modifications are made to the building, such as the addition of extra installations, including lighting.

This ceiling creep, combined with the hard pipe systems still found in many fire protection systems, means that while suspended ceilings may move with time, the sprinklers themselves remain in a fixed position as the ceiling slides slowly away. The result is sprinkler misalignment and loss of effectiveness to combat fires.

Wire cable is used to connect a suspended ceiling to the concrete structure of the building and hard piping is similarly fixed. However, because the fixed rigid piping does not move with the ceiling plane, if the ceiling drops there is a danger that a sprinkler will sit too high and be isolated from airflow in the room.

A properly installed sprinkler head needs unobstructed airflow access from the space being protected. If a sprinkler head is not properly positioned with the ceiling plane, the sprinkler will not be exposed to heat and airflow, leaving the ceiling to act as a heat deflector that potentially delays or prevents the sprinkler from activating in time to check the growth of a fire.

Recent figures from the NFPA show that in the US alone, 42 per cent of instances where sprinklers have not been effective were due to inadequate water reaching the fire. This figure could be improved by ensuring correct sprinkler head positioning.  

 

FLEXIBLE DROPS

Flexible drop and open-gate bracket solution to ceiling settlement

Flexible drop and open-gate bracket solution to ceiling settlement

A breakthrough solution to this problem came in the 1980s when engineers in Japan sought to cancel out the adverse effects of seismic activity on structures. With researchers looking to resolve problems caused by sections of buildings moving independently and at different rates, this led to the development and implementation of flexible hoses in place of conventional rigid pipe. These hoses are now known as flexible drops.

With a long history of development and use throughout the world, today this technology is being adopted at an increasingly high rate as more and more engineers, contractors and owners become aware of their benefits.

Flexible drop technology allows a sprinkler to move with the structure so it maintains the same position relative to a suspended ceiling even when settlement occurs. Unlike a traditional drop, which is not attached to the suspended ceiling, a flexible drop carries water from the branch line and delivers it to the sprinkler head using a specialised bracket to stabilise and attach the sprinkler head to the ceiling structure.

The legs of the bracket connect the sprinkler to the cross-beams in the ceiling so that it always moves with the ceiling and stays in the correct orientation.

In the 1990s flexible drop technology made its way to the United States, and a little later to Europe, where the first applications were in clean rooms. As they became more popular, their advantages for use in other applications such as suspended ceilings grew to be more apparent. As a result, UL developed a specific standard for flexible drops, known as UL 2443, Flexible Sprinkler Hose with Fittings for Fire Protection Service. Other ratings followed including FM Approvals and draft standard LPS 1261, with requirements for testing flexible drops for automatic sprinkler systems.

Flexible drop installed in crowded ceiling space

Flexible drop installed in crowded ceiling space

Companies such as Victaulic now have an established history of producing high-quality flexible drops which, in addition to their safety and performance benefits, offer significant cost and labour efficiencies on installation. They are up to 10 times faster to install than hard piping systems and installation is also simpler and less subject to error.

For example hard piping systems require distances to be measured and pipe to be cut and threaded. Frequently human error occurs: sections can be incorrectly measured or misaligned and have to be reworked or, worse still; the installation may be completed incorrectly leading to leaks and water damage. Flexible drop installation can be quickly learnt and the products are easier to install than hard pipe, and far more reliable than threading.

Flexible drops also present advantages for retrofits, particularly in modern high-rise buildings. Hard piping requires a cutting machine with oil to lubricate the pipe as it is being cut. Where additional sprinklers need to be installed in an existing building it is often necessary to locate the cutting machine outdoors and far removed to avoid interior soiling. In this case fitters must make numerous trips to prepare parts, which can be inconvenient and time consuming.

With flexible systems, a drop can simply be removed from its box and installed. It can be easily manipulated into position around obstacles without the need for elbows and cutting pipe to different lengths which takes time. For instance in situations where the space above a suspended ceiling is particularly in demand, this can be very useful.  An example would be a hospital with piping for heating and cooling, electrical conduits and compressed gas lines running through a crowded ceiling space.

 

LATEST DEVELOPMENTS

The latest generation of flexible drops have built on the original designs.  Braided hoses approved by FM and UL are now available, designed to offer tighter bend radii and an increased number of allowable bends, delivering extra performance; in turn making it is easier and quicker to position them in ceiling spaces correctly.

Meanwhile, additional improvements deliver significant and perhaps even greater benefits that make installation more efficient and help manage costs.

Potential hazards of hard piping with suspended ceilings, exaggerated for clarity

Potential hazards of hard piping with suspended ceilings, exaggerated for clarity

Earlier bracket designs consisted of four or more separate pieces – typically each leg, the centre bar and the square bar – that had to be assembled on site. When working on construction sites, in poorly-lit environments where there is little colour distinction between the concrete structures and bracket pieces, it is easy to mislay or lose a component.  At best, this results in lost time on the job.  At worst, if a component is lost the entire product needs to be replaced, leading to significant delays and additional costs. 

The latest one-piece bracket designs overcome these problems: the bracket comes preassembled with no loose parts to drop or lose. Centre-of-tile indicators on the bracket aid with correct positioning and increase safety.

Following extensive Victaulic R&D, developments in the technology allow better integration of fire protection installation into the construction schedule. Whereas standard brackets need to be installed after ceiling tiles are in place, some newer brackets offer installation options. 

Systems such as VicFlex from Victaulic are designed to install much more easily than traditional rigid piping systems whilst delivering more durable performance. They offer a convenient and safe solution that requires fewer man-hours to install, is cost effective for maintenance and retrofit applications and lowers shipping costs with a more compact form.

Next-generation brackets, like the Victaulic Style AB1 bracket, can be installed before ceiling tiles, which facilitates easier inspection. There is no longer a need for fire protection teams to cut tiles or coordinate with ceiling tiling teams to be on site at the same time. The fire protection system can be fully inspected on completion before any tiles are installed that might otherwise obstruct the view.

Recent examples of installs include the new 103.000 sq m/1,108,682 sq ft Kings Avenue Mall, one of the largest commercial developments in Cyprus. Over 7,000 Victaulic sprinkler heads were connected to branch lines using VicFlex, minimising installation time and maximising reliability. The system was also used in Duluth International Airport, USA, the Sinopec research facility in Chengdu, China and Nuevo Dorado International Airport in Bogota, Colombia.

 

CONCLUSION

From its introduction, the suspended ceiling has come a long way and, thanks to the evolution of flexible drops and the latest bracket technology, fire protection has been able to make the journey with it.

With proper sprinkler head positioning with the ceiling surface now much easier to achieve every time, safety in environments featuring suspended ceilings is greater than ever before. In addition, technical improvements mean that not only can systems be installed safely as well as quickly, but greater management and control of all areas of cost are possible.




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