Distributing Mains from service reservoirs are laid along streets with a minimum cover of 2 feet 6 inches to ensure protection against frost and traffic. They should split into multiple branches early on to limit the area affected by accidents. Dead ends and sharp bends in mains must be avoided to prevent stagnation and pressure loss. Pipes should be tested to twice their working pressure using hydraulic machines, ensuring a good working pressure of around 80 Ib per square inch for adequate water supply height.
Sluice valves are placed on mains at intervals of 800 to 1000 yards and at the start of each branch main. Hydrants are installed every 200 yards along mains, serving multiple purposes including fire extinguishing and emergency supplies during severe conditions. Intermittent water supply systems require large storage tanks for reserve water when the supply is off; constant systems are preferred today due to their reliability.
When tapping into a main under pressure, special appliances allow connection without shutting off the water supply. Service pipes can be made of lead, ternary alloy, galvanized iron, copper, or plastic, each with its own advantages and disadvantages based on water hardness and availability. Lead pipes are suitable for hard waters but require protection from corrosion when in contact with certain materials.
Inside buildings, stop valves should be placed just outside the boundary to protect against unauthorized access. Interior rising mains must have a fall towards the lowest point of the system for easy emptying during repairs or frost protection. Service pipe arrangements depend on whether constant or intermittent services are used; larger cisterns are necessary in areas with intermittent water supply.
<Callout type="important" title="Critical Safety Measure">Sluice valves must be placed at regular intervals to limit the area affected by any potential damage to mains.</Callout>
Service pipes should be fixed carefully to avoid damage, using appropriate methods for different materials. Iron pipes can use pipe hooks, while lead pipes are best secured with galvanized iron clips.
Key Takeaways
- Distributing mains should have a minimum cover of 2 feet 6 inches to protect against frost and traffic damage.
- Sluice valves are placed at intervals along water mains to limit the area affected by potential accidents.
- Service pipes can be made from various materials, each with specific advantages for different water conditions.
Practical Tips
- Ensure that distributing mains split into multiple branches early on to minimize disruption in case of an accident.
- Use appropriate pipe fixing methods based on the material to prevent damage and ensure longevity.
Warnings & Risks
- Avoid dead ends and sharp bends in water mains as they can lead to stagnation and pressure loss.
- Service pipes must be tested to twice their working pressure before installation to ensure reliability.
Modern Application
While the materials and some techniques described here are outdated, the principles of proper water supply system design remain crucial. Ensuring that distribution systems are robust against damage and can limit disruption in case of failure is as important today as it was a century ago.
Frequently Asked Questions
Q: What is the recommended distance between sluice valves on mains?
Sluice valves should be placed at intervals of 800 to 1000 yards along water mains and at the start of each branch main.
Q: Why are dead ends avoided in water mains?
Dead ends can lead to stagnation, which is undesirable as it may cause water quality issues. Sharp bends should also be avoided due to pressure loss they cause.
Q: What materials were commonly used for service pipes according to this chapter?
Service pipes could be made of lead, ternary alloy (an improved version of lead), galvanized iron, copper, or plastic. Each material had its own advantages and disadvantages based on water hardness.