Quality Control

To begin with the tests for quality need to be done when the dredge is in full operation. Every once in awhile the natural movements of the intake nozzle causes the sand to float and carried to the nozzle and this cannot be seen unless the suction tube is pulling the sand up in large amounts. Just looking at the water that is around the strainer is not enough to see if there is sand in it. Even in the case of the mountain streams that have very clear water, in many cases it is almost impossible to see light colored sands. You can sometimes place your hand inside the water next to the strainer and try to feel the sand (which is abrasive) by rubbing your thumb on your fingers. If you still need to test it even more then you can use a glass-drinking cup, hold your hand on top of the cup and put it next to the strainer. Take your hand off the top and allow the water to run and then close the opening again. Take the water sample up to the surface and allow it to sit for a few minutes, as this will cause the sand to settle to the bottom. If there is a good amount of sand there is a big possibility that the impellers will get damaged because of it.

Flow sand can be found in almost all streams and it is usually the heavier in a space of a few inches close to the stream bed. There are certain streams in which the flow sand can work its way up into the part of the stream that is faster moving. This is the reason why almost all dredge manufacturers make their dredge intake hoses so that they are able to only reach a few inches inside the water. In most cases the strainer position is quite on top of the danger level for sand to flow in however, you just might happen to have one that just so happens to be long enough to reach an area of the stream where the sand is flowing.

If this is the problem it can in many times be resolved by a float anchor arrangement. In order to do this a rope is tied to a float or somewhere on to the frame of the dredge as well as to the strainer pulling it up and out of the area where the sand is flowing. When it is situated this way the strainer can also be so high that it could pop out of the water once in awhile causing a deficiency of suction. In order to prevent this from occurring another little piece of rope can be tied to the foot valve with the other end tied to a rock or boulder that will be able to be used as an anchor and will keep the strainer in a steady position.