8 JANUARY 2023 WorldWide Drilling Resource® Installing Submersible Check Valves - When, Where, and Why Part 1 Adapted from Information by Laura Jensen, Flomatic Valves Within the water well industry, there are multiple resources available regarding the installation of submersible check valves. An issue which often sparks debate - installing one check valve versus multiple check valves for submersible pump applications. In a submersible pump application, check valves are critical to stop water from flowing downward in the pipe and returning into the well when the pump is turned off. To reduce long-term risks and damage to the pump, it is important to install multiple check valves rather than just one check valve. Most high-quality submersible pumps will have a check valve built-in from the manufacturer at the discharge. This will be the first check valve installed. The second check valve should be placed above the pump and no more than 25 feet above the water pumping level in a well. This way if the check valve at the pump fails, the second check valve in the system will hold the vacuum below it. Above this initial valve, submersible check valves should be placed every 200 feet in the drop pipe as permitted by well depth. For example, let’s look at a 750-footdeep well with the water level at 700 feet. This situation requires a total of five or six check valves to be installed. The system will have a check valve positioned at the pump discharge followed by another at 675 feet deep. Above the installation of these valves, there should be three more check valves installed every 200 feet on the drop pipe belowground putting them at 475 feet, 275 feet, and 75 feet deep. The sixth and final check valve, if necessary, is positioned at the surface. Many states require an additional check valve aboveground commonly positioned near the pressure tank. The ideal recommended installation location for the second check valve is one pipe length above the submersible pump. A valve in this position will be subject to laminar flow and isolated from the very turbulent conditions near the pump discharge. Check valves are vital components for the correct usage of submersible pump system applications worldwide. A common misconception is that just one submersible check valve is necessary for the entire system. Although high-quality check valves pressure rated to 400 psi or 923 feet of head pressure are built to last, this does not mean just one valve can be placed at 923 feet in a standalone unit. For every foot per second of velocity change in a steel pipe, 54 psi of back pressure is created. This means for a common one-inch well drop pipe with a flow of ten gallons per minute (gpm) could create a back pressure of 370 psi or more when the pump turns off and the water column reverses. In a four-inch pipe, a flow of 350 gpm could create a back pressure of 860 psi, resulting in more than what stock pump check valves are designed to handle. Staging check valves at even intervals along the riser pipe reduces hydraulic shock (water hammer) in stages, which protects the life span of valves, pump, and its pipes. Each check valve installed at 200 feet or less protects the one below it. The installation of numerous check valves allows for the system to absorb and lessen the shock above and below each check valve. Look for Part 2 next Month! WTR Empire StateWaterWell Drillers Association 2023 Annual Meeting Januar y17 18, 2023 Turning Stone Casino Verona, NY January 17th 7:30am Board Meeting 10am - Noon Primer for Rotary Drilling (preregistration required) Noon Lunch 1pm - 2pm Speaker - NY Workers’ Comp Changes 2:15pm - 3:15pm PFAS Changes 3:30pm - 4:30pm Business Succession 4:30pm - 7:30pm Cocktail Party, Auction, & Trade Show January 18th 9am General Membership Meeting
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