Fire hydrants are water outlet terminals strategically located along streets to provide water to firefighters for dousing flames. The firefighters tap into the fire hydrants using flexible hose pipes to refill the fire engines. Also, the fire hydrants are used to drain hydraulic systems. Since fires seldom occur, fire hydrants are rarely used. Therefore, the fire hydrants are likely to go out of service or malfunction due to rusting and oxidation of the metallic parts. To ensure that the hydrants are still in good working condition, fire hydrant flow testing is required. This is a paper on the procedure and importance and fire hydrant flow testing
The main purpose of fire hydrant flow tests is to determine the flow rate and capabilities of the hydraulic system in terms pressure and reliability. The obtained figures help firefighters in planning their operations with regard to the type of equipment to use and the best locations to tap water from the hydraulic system. Also, insurers use the flow rate and pressure values to set premiums for fire cover policies. In addition, the data is used by designers and developers in the real estate sector. For example, building designers use the pressure values in the hydraulic system when designing sprinkler systems used to put out flames in buildings. Designers in real estate developments also use the values to align project requirements with the available flow rates and pressure.
Also, fire hydrant flow tests indicate the condition of distribution system. Due to impurities in the water, deposits form on the pipes and clog and reduce the flow rate and the general capacity of the system. Such occurrences are detected through reduced flow rate values. Fire hydrant tests are conducted every ten years or as required to identify any significant changes in the hydraulic system. The test results are then recorded and systematically filed for future reference.
Fire hydrant flow tests are usually done in the morning when water usage is high. The results of such a consumption peak test depict the worst case scenario when the flow rates and pressure are at the lowest possible values. Pressure between the off peak and peak hours can fluctuate by up to 10 psi. The equipment used for the test includes a pressure gauge, flow meter, and an air release cock. The fire hydrant test begins by identifying a suitable hydrant, whose nozzle cap is then removed and a pressure gauge is attached to the outlet. Pressure is then recorded when the gauge needle stabilizes.
Hydrant tests are essential while formulating hydraulic designs. For example, the test results can be used in the design and sizing of firefighting systems in buildings. Design engineers can use the pressure and flow rate values to determine the type of piping and sprinklers to use in a building for firefighting applications [1]. Also, the pressure values can be used to determine the effective height, to which the hydraulic system can supply water in high rise buildings.
Apart from designing sprinklers, hydrant tests result are useful in the design of water pumping systems used in firefighting applications. Engineers use the pressure values and flow rate available at a given location to determine the suitable type and power rating of the required pump in line with the flow rate demand and pressure. For example, engineers use the pressure and flow rate values to determine the power curve of the suitable pump [2]. The power curve is a graph that defines the flow rate against pressure of a given curve. The design engineers match the flow rate and pressure from the hydrant tests to the various pump power curves in the pump selection process.
Works Cited
[1] D. Blossom. “How Reliable are Private Fire Hydrants?” Internet: http://www.fireengineering.com/articles/print/volume-158/issue-2/features/how-reliable-are-private-fire-hydrants.html 2005 [Feb. 13, 2016].
[2] S. Dannaway. “The Fire Hydrant Flow Test: Part III.” Internet: http://plumbingengineer.com/content/fire-hydrant-flow-test-part-iii, n.d. [Feb. 13, 2016].
