DRY RISER:
•A vertical pipe installed in a building with a landing valves at various floors, which are normally dry but are capable of being charged with water using fire pumps.
•They are dry water pipes.
•The use of the Dry riser should be restricted from building of floors 10M to 60M, above that the pumping pressure would increase drastically which would not be cost effective.
•Dry riser is recommended to be used n cold climate where chances of water in the pipe freezing are high.
DOWN COMER SYSTEM:
•Down comers are only permitted for private residential buildings with open balcony approach where the topmost floor is not higher than 60 meters above the fire appliance access level and should be adopted for low cost flats only.
•Down comers system comprises a high level water storage tank discharging into 150mm diameter riser pipe with landing valves at each floor and to which canvas hose with nozzles can be connected to direct the water jet at the fire. No pumps are provided and therefore the system pressure is limited to the static pressure only.
