FULL OUTLET STRAINER DESIGN CONSIDERATIONS
Mer-Made FO Series strainers have been designed to achieve lower pressure losses and higher debris holding capacity. These units have been tested for pressure loss (clean basket). In addition, tests were run using grass clippings as a medium to establish a comparison between “dirty-up” time for our design versus the standard designs being offered by competitors.
Mer-Made FO Series (full outlet) strainers are built with a large outlet area in the basket chamber. Historically, strainers have been required to have a basket total open area that is a multiple of incoming pipe area. A typical code or specification may call for a basket open area to be four times the incoming pipe area. Tests have shown, however, that in many designs very little of the basket area is used before a maximum pressure loss, (say 5 psi) is achieved. The usefulness of the strainer basket is much more dependent on the amount of opening in the chamber that houses the basket. To achieve a significant strainer performance improvement we have increased this area considerably.
To best understand the evolution of our design, refer to the sketches below. A “T” type strainer is frequently offered as “equal” to a Mer-Made FO Series design but these sketches highlight the differences.
NOTE: The Mer-Made has a complete outlet section built onto the basket chamber and this is what allows the greatly improved outlet area.
PRESSURE LOSSES VS. FLOW
PRESSURE LOSSES VS. FLOWTIME
NOTE: A test to establish rate of increase of pressure drop versus debris loading was simulated by adding 50 ml of grass clippings every two minutes to 1000 gpm of flow