Piranha Mini Dredge

First of all, a self priming pump alone is not very effective in removing sediment. The agitator water jet system is necessary to deliver kinetic energy (energy of motion) to the sediment to take it from a solid state rendering it a fluid slurry.

Cheap trash pumps are not designed to withstand abrasion or shock. Cheap trash pumps usually utilize small diameter carbon/ ceramic shaft seals. Carbon/ceramic is the cheapest seal material there is and is a strong indication that your pump is designed to pump water only. The shaft seal is the component that seals the engine shaft as it enters the pump case. A leaky shaft seal will disable your pump completely, by allowing air to enter the pump case instead of water being drawn up the suction hose. The Mini dredge pump is equipped with an oversized silicon carbide shaft seal. Silicon carbide is a premium seal material that is utilized in most industrial grade pumps. We also make the seal much larger in diameter than those found in most “trash pumps”. Small diameter seals fit snug on the drive shaft. When a hard piece of debris (rock, wood, etc) hits the pump impeller, it deflects the shaft momentarily and fractures the seal. Our seals have a large inside diameter with a lot of space between the seal and the shaft preventing seal damage from shock. Also, in order for mechanical seals to work, they all utilize a stainless steel compression spring to hold the seal faces together. Lazy pump manufacturers, leave that spring exposed in the water way behind the impeller, rendering it vulnerable to abrasive wear and to collecting stringy material & debris. Our seal spring is tucked away in a recess machined in the pump housing, sealed away from abrasives and debris.

The second most vulnerable component to abrasive wear is the impeller. You will find that most trash pumps have a cast iron impeller. Cast iron is popular inexpensive material, and serves adequately for non-abrasive pump applications. The next level above cast iron is ductile iron. Then comes heat treated stainless steel. The top abrasion resistant impeller material is high chrome iron. High chrome iron impellers are usually only found in severe duty industrial slurry pumps because they are so hard they are expensive to machine. The Mini dredge has a high chrome iron impeller.

We manufacture the Mini dredge with innovative design features from the highest quality components & materials, too many to list here. We could make a cheaper dredge, but it wouldn’t work as well or last as long. We’ve been manufacturing industrial grade pumps for over 40 years. We are very critical about quality, and we make our pumps as if we are building them for ourselves.

That’s like asking about the difference between apples and oranges. A gold mining dredge has a totally different design and purpose. A gold mining dredge utilizes a device called an “eductor” in conjunction with an inexpensive water pump. This system is designed to pump a lot of water with low slurry content a relatively short distance, usually into a nearby sluice, and is normally deployed by a scuba diver. The Mini dredge does the opposite. It moves large quantities of slurry a great distance (up to 900 feet).

This depends upon the vertical elevation differential, and the type of sediment.

The vertical elevation differential, otherwise known as “static head”, is the elevation difference from the surface of the water body to the point of discharge. There are two important factors to point out here. First, it does not matter how far the sediment is below the water surface. Static head begins at the water surface. Secondly, it makes no difference if your discharge is going up and over a hill. The static head begins at the water surface, and ends at the open end of the discharge hose. For example: if your are dredging from a lake, and your discharge hose runs up over a 30 foot high dam, then down 20 vertical feet the other side of the dam, then your static head is 10 feet.

The type of sediment will have some effect on the production rate and on the distance that you are able to pump it. Most of our customers are dealing with either black stinky fluffy mud, or sand. The Mini dredge works well with both types of material.

In order to transport a slurry through a pipe or hose, it must maintain a minimum velocity to prevent the sediment from settling in the hose, eventually forming a restriction or plug. The term for this is “minimum critical carrying velocity”. The text book minimum velocity for mud is 3 to 5 feet per second. We prefer to utilize a more conservative value of 7 feet per second. The text book minimum velocity for sand is 5 to 7 feet per second. Again, we prefer to utilize a more conservative value of 9 feet per second.

Velocity is defined by the flow in gallons per minute, and the discharge hose diameter. 154 gallons per minute through a 3 inch hose translates to 7 feet per second, the minimum velocity for transporting mud. 198 gallons per minute represents 9 feet per second, the minimum velocity for sand. As you increase either the static head or the discharge hose length, you are simultaneously decreasing the flow and velocity.

To utilize the table below, estimate the total length of discharge hose. 15 feet of static head is roughly equivalent to 100 feet of hose. Add 100 feet for every 15 feet of static head. For example: you have 200 feet of actual discharge hose, and 30 feet of static head, then, utilize the 400 foot discharge hose value in the left hand column. Your flow will be 200 gpm, velocity 9.99 feet per second (plenty for both sand and mud), and your dredging capabilities will be 19 cubic yards per hour for sand, 22 yards for mud. If you call us with your actual parameters, we will plot a precise computer generated graph of your dredge performance. Following is general performance data pertaining to our dredge model PS135E.

That is like asking, if I get in the back seat of my car, will it take me to work? This is a piece of machinery that requires an attendant.

The answer is no. A $500,000 dredge would not do that. Dredges excavate sediment. That means sand, mud, decayed vegetation, sewage, gravel, shells, and virtually any type of sediment that is broken down into small particles that are not glued together. Dredges will not pump lily pads, moss, or any other stringy vegetation.

The answer is yes, but there are some limitations. Our standard suction head has a strainer with 1 1/2 inch square holes the material must pass through before entering the suction hose. Leaves will have a tendency to collect on the strainer and starve the pump. We also offer a modified “leaf strainer” with 3 inch square holes. The “leaf strainer” allows a generous path for leaves to pass. However, it must be used with some caution. The standard strainer is designed to prevent large rocks, chunks of wood, etc, from damaging the pump. By utilizing the leaf strainer, you are eliminating this safe guard. Also, the dredge is intended to primarily excavate sediment with leaves scattered in the mix, and not the other way around. In other words, if you have clumps of leaves, or thick layers of leaves, you would be better off removing them by some other method.

The term "clay" is actually a definition of particle size, although most people think of clay as gooey sticky mud that is difficult to wash off your shoes. An easy way to determine whether or not your material is suitable for the dredge, is to put a ball of it in a jar of water and shake it vigorously a few times. If it does not completely fall apart in the jar, then you are not going to be able to pump it.

Salt water is fine but you will need to take extra care to hose the pumps and engines with fresh water after every use. The pontoon floats are made of high density polyethylene (HDPE), and are extremely resistant to salt, chemicals, and ultraviolet light. The frame has an oven baked urethane powder coated finish that is also resistant to corrosion and UV light. Also the pontoons are secured to the frame with stainless steel fasteners.

That will depend upon the type of sediment you are pumping, and how extensively you use it. Sand is by far more abrasive than mud, and will wear your pump much more quickly. The key wear components in the dredge pump are made of highly abrasion resistant materials, are designed to withstand sand abrasion, and are relatively easy to replace with new parts. If you are utilizing it for intermittent cleaning of limited areas such as boat docks, waterfront, channels & canals, then you can expect it to run a long time before wearing anything out. On the other hand, if you are planning to pump sand for 10 hours a day for months, then you need to invest in one of our industrial dredges.