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With many new construction endeavors, underground PVC conduit sometimes must be encased in concrete or slurry. As you probably know, current products and procedures aren't always successful in preventing conduit from floating. Keeping the conduit in place and from floating is a challenge, one that can be time consuming, costly, aggravating and dangerous. But there is a solution. It's the patented Sta-Down conduit retaining device (CRD).
Sta-Down CRD secures PVC conduit in the trench, while it's being encased in concrete or slurry. It does so without steel stakes, EMT or tie wire coming in contact with the conduit. "Contractors, in the past, would use whatever they could find, steel stakes, EMT, rebar or even cement blocks to counter the floating," notes Dan Evans, owner, Devtron Diversified, manufacturer of the Sta-Down CRD. "This product solves that problem."
By its very nature, PVC conduit is buoyant and will "float" or rise in the trench while being encased. Some procedures used, and cited earlier, to prevent the "floating" can cause electrical induction as voltage runs through the conduit and tries to "jump out" to metal inductors. In addition, methods such as concrete blocks or rocks to keep the conduit from floating can prevent proper encasement of the conduit and cause other problems down the road.
Evans cites other problems from these "solutions." A main problem point is that excavating equipment can snag the steel stakes, rebar or EMT, which can compromise the conduit and damage the cable. This, of course, can result in costly repairs, loss of service, and even injury or death to workers.
"No one has ever designed a specific product made of PVC to address the issue of floating conduit," Evans claims. "I have worked in the excavating industry most of my life, and encountered this problem, so I decided to do something about it. It's always been my basic approach and philosophy to find a solution."
In fact, Evans has been an innovator and inventor for much of his life. Another product that he invented, which is successful and used by U.S. soldiers, is the Scopecoat protective cover for sporting and combat optics.
How process works
Sta-Down CRD is made entirely of injection-molded polypropylene plastic that slips into the ends of 1½-inch schedule 40 conduit. To install, cut 1½-inch schedule 40 conduit to approximately 1¾-inch shorter than the trench width, Evans explains. Then, insert CRD, one in each end of conduit with the "louvers" pointing upwards. Evenly push the CRD down on the installed conduit bank with firm resistance where the CRD comes into contact with the trench bank.
