Cost Savings | on February 14th, 2021
Fire sprinkler systems are the first line of defence against fire in a building, hence its design and material choice is not only regulated by global/national codes and local guidelines, but also deserves special attention.
Traditionally, India has been using Metal Pipes (GI/MS ) for the fire sprinkler systems. Metal pipes are prone to corrosion, MIC (microbiological corrosion) and metal oxidation, scale build up and are also difficult to install. These issues hamper the performance of the fire sprinklers.
BlazeMaster® CPVC fire fighting systems used for fire sprinkler piping help overcome the issues of MIC and metal oxidation, scale build up (and eases installation as well, more on this later) and further the smooth inner surface of the pipe assists the flow of water to the sprinklers.
Further by adopting hydraulic design adds great value and helps in optimization of pipe size to the actual pressure loss and this leads to a sustainable design.
Let us see how.
Efficient Fire Sprinkler System
A Fire Protection System (and its Piping) too can be designed using one of the two methods.
- Pipe Scheduling
- Hydraulic Calculation
Design and Engineering play a very important role in making a Fire Protection System efficient and cost effective.
When designers use empirical assumptions, extrapolations and incorporate a safety factor to offset errors- they tend to add inefficiencies in the system. Thus, outdated Pipe Schedule System can lead to the usage of pipes that are larger than needed which may lead to an increase in the cost of labor and materials.
A better method will be to calculate and design an entire system instead to depending on available schedules and simplified engineering charts.
Bureau of Indian Standards (BIS) 15105:2002 broadly explains Hydraulic Calculation as a calculation that shows that each trunk main together with any branch main, from each water supply to a main installation control valve set water supply test and drain valve and control valve ‘C’ gauge is capable of providing the required pressure and flow at installation control valve test and drain valve.
While in Pipe Scheduling, the designer chooses the no. of sprinklers vis-à-vis pipe sizes based on available schedules, the hydraulic design gives the power of customize the fire sprinkler system. It is based on actual pressure loss and ensures the required coverage and adequate flow. It can mean using smaller pipes and fewer sizes of pipe, thus saving time and money.
Hazen-William’s Formula
The Hazen-Williams formula is the equation that’s long been used for calculating the friction loss in pipe systems. It determines the appropriate size of pipe and sprinklers to use in a fire protection system by calculating actual pressure loss based on the length of pipe and internal friction.
The less friction there is, the more easily the water can flow, limiting pressure and allowing for smaller pipe sizes.
Thus, when designers choose BlazeMaster® CPVC Pipes over metal, they are able to utilize its smoother internal surface to reducing pressure loss.
For BlazeMaster® ( C = 150), a narrower internal diameter of the pipe can be used as compared to a new steel pipe ( C= 120, and diminishes over time) to achieve the same flow rate. Thus the possibility to downsize fire sprinkler pipes becomes a practical reality.
Click here to learn more on Hazen-William’s Formula.
In case you want to learn more about fire sprinkler systems, Contact BlazeMaster®
Codes & Standards
National Fire Protection Association (NFPA) and Bureau of Indian Standards (BIS) prefers usage of Hydraulic Calculation for designing Fire Sprinkler System. The NFPA 13 Handbook, 2016 edition, states: “A sprinkler system designed using hydraulic (calculation) is preferable over those systems designed using a pipe schedule approach.”
BIS 15015:2002 also mandates using Hydraulic Calculation for all pre-calculated sprinkler arrays. As per extract of sub-section 12.4.1.2, ‘‘The feed pipe between the installation main control valves and the design point shall be hydraulically calculated on the basis of maximum flow loss...”
BIS 16088:2012 also highlights advantage of CPVC Pipes over steel from Hydraulic design perspective.
‘CPVC pipes are light weight, easy to carry and install, corrosion resistant with very high life expectancy. They possess better hydraulic characteristics having Hazen William C factor of 150 as against 120 of steel pipes. As such it is an ideal choice for any designer to prefer CPVC material over metal for fire sprinkler systems. In case of fire it is self extinguishing because of its high Limiting Oxygen Index (LOI) of 60 and it requires very high percentage of oxygen in the atmosphere to keep burning.
CPVC pipes have already replaced steel pipes for installation of automatic sprinkler fire extinguishing system in most of the countries across the world and are successfully rendering trouble free service since 1986.’
In a Nutshell
Steel pipes have their own merits and have been used for water distribution in a fire sprinkler system for decades - but when it comes to hydraulics, steel pipes do not match up to BlazeMaster® Pipes.
There is a reason for that. BlazeMaster® CPVC has a consistent Hazen-Williams C Factor of 150 whereas steel has a starting C Factor of 120, and that also diminishes over time due to corrosion and scaling. The interior surface of BlazeMaster® CPVC pipe is smoother than metal pipes, creating less friction to interfere with water flow and this enables the piping system to have an equivalent flow rate through smaller and fewer pipes, which ultimately results in savings on material and labor costs.
Hydraulics calculation is an accurate and preferred method for designing fire sprinkler systems because it works for all types of systems and pipe materials.
