Hydraulic Testing of Media Filter Cartridge
Client: Well-known stormwater treatment equipment manufacturer.
Background: As rain falls, it naturally makes its way to local water bodies and groundwater supplies. As it travels it collects sediment, litter and chemicals from the impervious areas, such as streets and parking lots, that it travels over. This increases water-pollution levels. Stormwater filters capture sediment and attached pollutants in the water and help protect the environment.
The client’s storm water filter system includes a cartridge which is essentially a cage filled with granular media. At the center of the cage is a slotted core that allows the treated effluent to drain out. The slotted core is mounted into a socket coupling which then sits on a socket bushing inserted through a hole in the base of the cage.
The client was securing the core by taking a standard socket coupling and cutting it in half, horizontally, to produce 2 couplings. Following the cutting step, some machining on the edges of the two pieces was required to ensure proper fit. The use of shorter couplings exposed more of the core which lead to lower head loss through the system.
Problem: Cutting and machining of the coupling was labour intensive in addition to being costly and time consuming.
Solution: The client requested testing to see if using the full standard ‘off-the-shelf’ coupling without cutting or machining would still yield results within an acceptable range. If successful, this could reduce time and cost in assembling the cartridge considerably.
Action Required: GHL conducted a full study to examine system head loss with both the standard ‘off-the-shelf’ and modified couplings.
A hose connected to the mainline water source was used to produce the required flow rates. A meter stick was used to determine the head loss in the cartridge compartment and the bucket and stopwatch method was used to calculate the flow rate exiting the vault. The height of the static water line was determined in relation to the bottom of the vault. For the purpose of constructing a head loss vs. flow curve, the target flow rates were between 5 and 40 gpm.
Result: GHL’s tests concluded that the increase in headloss with the higher coupling was insignificant, only a couple cm higher at maximum flow than with the short coupling. Based on the results the client was able to conclude that the benefit of using a standard part outweighed the slight change in performance.
Benefit: The client, since revising their assembly process according to GHL’s recommendations, has seen a significant reduction in time and costs associated when assembling their cartridges.