True Invention Story About Inventing A Conduit Sealing Device - Free Invention Help For Newbie Inventors.

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True Invention Story About Inventing A Conduit Sealing Device

Invention:  Method for Sealing Cable Conduits   Pat No:  5,304,396 


Real invention stories.

As I recall, this invention began with a call one day from a friend of mine who told me I could make a bunch of money if I could figure out how to some other guys product work correctly.  I was intrigued.   He told me this guy had a product used to seal the conduits that run under streets, but it wasn't working correctly. 

The product was a double syringe and mixing nozzle that sprayed a two part foam mixture into the end of a conduit. The mixture would foam up and seal the conduit against water.  The problem was that when the conduits would crack as many did, water would get into the conduit and empty out into the vaults under the street, filling the vaults with water, making it difficult to work in them during the winter.

We set up a meeting between myself and the conduit-sealing-guy whom I shall refer to as "Mr. C".  Mr. C explained to me that the mixing element in the 6" long nozzle did not mix the chemicals well enough, and he told me if I could develop a better nozzle he would pay me a royalty of 5 cents for each nozzle he sold. He wanted patent protection of course.

At that point in time he was selling about 60,000 nozzles a month, and was predicting sales of over 100,000 nozzles per month within the next 6 months. Jeez...and they didn't even work!  He was quite anxious to solve the problem before his customers discovered that the products did not work.

He had contracts with large utilities and phone companies such as Bell South, and Pacific Gas & Electric.

I accepted the challenge, and set about to develop a better mixing element for the nozzle. 


Inventing the mixing element

Mr. C explained that if you used the syringe to fill a plastic cup with foam, you could tell from the size and uniformity of the bubbles and by how much un-foamed chemicals remained at the bottom of the cup after the mixture foamed, how well the two chemicals were mixed.

Ideally you would want very small uniformly sized bubbles and no left over chemicals at the bottom.  So I got a couple of cases of his syringe foam kits and bought a few hundred plastic cups from the grocery store.

I used the "Thomas Edison" method of inventing....try lots of different mixing methods until I found something that worked.

I pulled the mixing elements out of the nozzles and tried making a wide variety of mixing elements, stuffing them back into the nozzles and filling plastic cups. After about two weeks I had a mixing element that did a much better job of mixing the two chemicals than the original ones.  The foam was beautiful with very uniform tiny bubbles and little and often with no left over chemicals in the bottom of the cup.

I took several of the new nozzles to a meeting with Mr. C.  He was delighted with the foam, and invited me to watch a test that his product had to pass in order to get the sales contracts he had.  None of his clients had actually tested his product...yet.

A 12 foot long 4" diameter PVC section of conduit was set up at about a 45 degree angle from horizontal.  Several cables were placed partially into the lower end of the conduit.  A piece of soft foam rubber was pushed up into the conduit about a foot in from the end.  Another piece of foam was place just inside the end of the conduit, creating a space of 10 or 12 inches between the foam rubber "dams", to contain the mixture until it foamed up.  That way the foam wouldn't just run out the end or down the conduit, but was forced to completely block the conduit.

The nozzle was then inserted through the first "dam" and the chemicals injected into the space between the dams.  The mixture foamed up and pushed the front dam out of the conduit. We then waited an hour for the foam hardened.  

Next water was poured into the conduit's upper end.  To pass the test there could be no leakage for one hour.

It took about 10 minutes for the water to leak through.  It did not pass.

Ah Ha!  Mr. C had asked me to create a better mixing element for the nozzle, but the mixing wasn't the problem, he had made an erroneous assumption.  This was now a whole different ball game. 

I asked Mr. C why he thought the foam would seal the conduit. He explained that his double syringe with nozzle was an improvement over his competitors products.  The same two chemicals were used, but instead of a mixing nozzle and double syringe, it was a single syringe with a separator in the middle.  When you wanted to seal a conduit you broke the middle section, worked a plunger to mix the chemicals, and injected it into the conduit. 

Okay, its the same stuff...but obviously something was different. The other system does seal the conduit...maybe there is still and invention in here somewhere...

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