Streamline - Summer 2011 - (Page 31)
Hydrant Flow Testing – Data You Need
BY MARK A. NORRIS, CIRCUIT RIDER II
THE PURPOSE OF flow testing is to collect data on flows and pressures from fire hydrants within a city or town’s distribution system. This data can be used to ensure public safety. Fire Departments, engineers and city planners can use this information to provide adequate supply and pressure to meet system demands and fire protection. This information can also be used in water modeling that allows for system improvements, residential and commercial developments to be evaluated on how they will impact a system.
Prior to testing, ﬂushing the lines may be necessary to remove build up and sediment. This will allow for more accurate results when ﬂow testing is performed.
Prior to testing, flushing the lines may be necessary to remove build up and sediment. This will allow for more accurate results when flow testing is performed. Notifying customers about flow testing in their area will help keep complaints to a minimum, as pressures will fluctuate and water quality may be altered by discoloration from sediments stirred up in the pipes. Informing the fire department would be a good idea as well. Some localities, after collecting the flow data, will paint their hydrants, following the national uniform code for fire departments. This allows a fireman to know what flow he can expect out of that hydrant based on the color of the caps and turret. While flushing, consider where to divert the flow of water. Electrical lines, landscape erosion and traffic can all become safety hazards while having flows with high volumes and pressures. Additionally, you may find it necessary to use dechlorination equipment to protect the environment around the test site. Deciding on what time of day to perform your testing can offset the accuracy of your data. In residential areas where everyone is at work and school, you may have better flows and pressures compared to peak demand times when everyone is showering, washing clothes and washing dishes. High demand commercial areas may also affect data if you’re testing those areas during off peak times. So you
see how planning times and locations are important. To perform the testing, a few pieces of equipment and manpower are all you need. On the test or flow hydrant, you will have a pilot gauge. This gauge will show flow and pressure on it. This hydrant will also use a diffuser, which helps break up that strong stream of water. On hydrants upstream and downstream, there will be pressure gauges. Prior to the test, a static reading is recorded. Then, the hydrant is slowly opened (to prevent water hammer) using a hydrant wrench. Pressures are recorded. Flows and pressures are recorded on the test hydrant and then the hydrant is slowly closed (to prevent water hammer). After testing, the static pressures are recorded again to ensure that the pumps work properly and that no water main pipes broke during testing.
Data is usually recorded on a data sheet that includes:
• • • • • •
Hydrant inventory number Location of hydrant Manufacturer and Model Time and date Static, residual and static readings Flow information and comment section
This information can now be utilized by your GIS personnel, engineers for water modeling and fire departments. This allows for any areas or hydrants that have problems to be detected before they can become an emergency or are needed during one, and realizing that they aren’t working properly. As always, if I or any of the VRWA staff can be of assistance with flow testing, please feel free to contact us at (540) 261-7178.
Table of Contents for the Digital Edition of Streamline - Summer 2011
From the President
From the Executive Director
The Water Tastes Good in Western Virginia
Virginia WARN, Help in an Emergency
Proper Disposal of Pharmacy Products
VELAP: Where Are We Now?
Why Did the Paramecium Cross the Road?
Anger in the Work Place: What It Really Costs You
Litigation and Water Wars
Hydrant Flow Testing–Data You Need
What A Ride!
Conference 2011 Highlights
Throwing My Loop
Do You Know What Your VRWA Benefits Are?
New VRWA Benefit
Welcoming New Members
Board Of Directors
Index To Advertisers/ Ad.Com
Streamline - Summer 2011