Dry & Wet Risers

At South East Sprinklers & Dry Risers Ltd. we understand the importance of servicing your installation and keeping it safe and functioning correctly.

Dry Risers

Dry risers and hydrants are used to supply water within buildings for firefighting purposes. The provision of a built-in water distribution system means that firefighters do not need to run their hose from the fire engine to the fire source.

Installation

All risers and hydrants are installed to fully conform with BS9990. The design and installation of risers and hydrants meet all the design considerations set out in British standards in order to provide systems that allow unobstructed access for fire fighters and will allow for the correct water flows at each outlet.

Dry risers should all be designed and installed to a working pressure of 12 bar with a normal bore diameter off 100mm dry risers mains and associated pipework and fittings should be of suitable heavy quality steel to meet the pressure, robustness and durability requirements of the system.

Dry risers inlets should be fitted with a two-way inlet breeching for 100 mm mains. Each breeching should conform to BS 5041-3. And should be installed between 400mm and 600mm from ground level with a 25mm drain valve as the system should be left dry at all times.

All dry risers outlets should be installed at 750mm from finished floor level at the lowest point of the valve. With a air release valve fitted on the highest point of the dry riser. all dry risers should be designed to supply 1500lpm at each valve although pressure requirements are not necessary as this will be supplied by the fire rescue service pumps.

Specifications

• All Installations installed to British standards and conform to BS9990
• Systems tested to 12 bar, as set out in British standards
• Pipework and outlets are provided with fixed to suit the building and client requirements
• Equipment conforms with BS5041 where required

Maintainence

Dry risers should have a water test to BS 9990 annually this test involves connecting a service test pump the dry riser inlet and pressurising the system to 12 bar for at least 15 minutes. A half annual service inspection is also required.

All valves, clamps and pipe work should be checked to insure there are no leaks, damage or corrosion on the dry riser.

Wet Risers

Wet risers are essential for high rise builder where a the fire and rescue service pumps are not able to achieve the water flow and pressure requirements necessary in the event of a fire. All wet risers should have a minimum bore size off 100mm with a outlet on every floor including ground level.

Its essential for wet risers to be fully loaded and under working pressure at all times to supply working pressure at 2 fire fighting outlets at one time.

Wet risers require there own tanks and pumps and are designed to accommodate 1500lpm for as duration of 45 minutes. Each pump should be capable of giving 1500lpm each running at 8 bar of pressure.

Maintenance

Wet risers annually require a flow test carried out, to at least 2 landing valves on the system at one time. This is to m,ake sure the correct flows and pressure is being reached on demand in the event of a fire.

All valves should have the pressure checked once a year. The wet riser pumps need to be serviced every year. All valves, clamps and pipe work needs to be checked for leaks, damage and corrosion.

Hydrants

Wet Pressure Test

This involves fitting a standpipe to the outlet, partially opening the valve to allow a small amount of water to flow. A blank cap is fitted in the standpipe head and the hydrant fully opened. Whilst under pressure, all joints are to be visually inspected for signs of leakage. Leaks that would impair the hydrant for fire-fighting purposes or cause a hazard will be reported immediately.

Static Pressure Test

The static pressure test is conducted by attaching a static pressure assembly to the standpipe with the vent cock open. The hydrant is opened, and the vent cock is closed when the standpipe is free of air. A pressure reading will be taken. The hydrant is closed, and the vent cock is opened to release the pressure before removing the standpipe assembly.

Flow Test

Before attaching the flow tube to the hydrant standpipe, the main be flushed for a short period of time (approximately one minute) to clear any debris which may cause damage to the flow sensor. After flushing, the flow tube is attached to the standpipe and the hydrant valve is fully opened. The digital display is left to settle before any readings are taken.