VALVE USE

In order to meet the needs of a properly designed water collection system, various types of valves are used. They control where different types of water can and cannot go. Construction materials vary according to local regulations, but polyvinyl chloride (PVC), stainless steel, and copper/bronze are the most common.

Having said that, there are exceptions. Projects designated to meet the “Living Building Challenge” require strict green building standards and prohibit the use of PVC and other materials that are considered harmful to the environment due to manufacturing processes or disposal methods.

In addition to materials, there are options for design and valve type. The rest of this article looks at common rainwater and greywater collection system designs and how to use different types of valves in each design.

Generally speaking, how the collected water will be reused and how local plumbing codes are applied will affect the type of valve used. Another reality under consideration is that the amount of water available for collection may not be sufficient to meet 100% reuse requirements. In this case, domestic (drinking water) water may be included in the system to make up for the deficiency.

The main concern of the public health and pipeline regulatory agencies is to separate domestic water sources from the interconnection of collected water and the potential contamination of domestic drinking water supplies.

STORAGE/SANITATION

The daily water tank can be used to flush toilets and disinfection containers for cooling tower supplementary applications. For irrigation systems, it is common to pump water directly from the reservoir for reuse. In this case, the water directly enters the final filtration and sanitation step before leaving the sprinklers of the irrigation system.

Ball valves are usually used for water collection because they can open and close quickly, have full port flow distribution and low pressure loss. Good design allows equipment to be isolated for maintenance without disrupting the entire system. For example, a common practice is to use ball valves on tank nozzles to repair downstream equipment without having to empty the tank. The pump has an isolation valve, which allows the pump to be repaired without draining the entire pipeline. A backflow prevention valve (check valve) is also used in the isolation process (Figure 3).

PREVENTING CONTAMINATION/TREATMENT

Preventing backflow is an important part of any water collection system. Spherical check valves are usually used to prevent pipe backflow when the pump is shut off and system pressure is lost. Check valves are also used to prevent domestic water or collected water from flowing back, which can cause water to be contaminated or invade where no one wants it.

When the metering pump adds chlorine or blue dye chemicals to the pressurized line, a small check valve called an injection valve is used.

A large wafer or disc check valve is used with the overflow system on the storage tank to prevent backflow of the sewer and rodent intrusion into the water collection system.

17 sum water fig5 Manually or electrically operated butterfly valves are used as shut-off valves for large pipelines (Figure 5). For underground applications, manual, gear-operated butterfly valves are used to shut off the water flow in the water tank, which can usually hold hundreds of thousands of gallons of water, so that the pump in the wet well can be repaired safely and easily. The shaft extension allows control of valves below the slope from the slope level.

Some designers also use lug-type butterfly valves, which can remove downstream pipelines, so the valve can become a shut-off valve. These lug butterfly valves are bolted to mating flanges on both sides of the valve. (Wafer butterfly valve does not allow this function). Note that in Figure 5, the valve and extension are located in the wet well, so the valve can be serviced without a valve box.

When low-level applications such as water tank drainage need to drive the valve, the electric valve is not a practical choice because the electric actuator often fails in the presence of water. On the other hand, pneumatic valves are usually excluded due to lack of compressed air supply. Hydraulic (hydraulic) actuated valves are usually the solution. An electric pilot solenoid safely located near the control panel can deliver pressurized water to a normally closed hydraulic actuator, which can open or close the valve even when the actuator is submerged. For hydraulic actuators, there is no danger of water coming into contact with the actuator, which is the case with electric actuators.

in conclusion
On-site water reuse systems are no different from other systems that must control flow. Most of the principles that apply to valves and other mechanical water treatment systems are simply adopted in different ways to meet the unique requirements of this emerging field of the water industry. Nevertheless, as the call for more sustainable buildings increases every day, this industry is likely to be important to the valve industry.