Piranha Pumps & Dredges: dewatering, slurry, solids, floating pumps

About Mini Dredges

Models PS-135-E / PS-165-E / PS-165-ER
13.5 & 16.5 Horsepower 
For Removing Sand & Mud From: Marinas, Boat Docks, Canals, Ponds & Waterfront Property

Models PS-135-E & PS-165-E

The Piranha Mini dredge was developed in response to thousands of requests received from waterfront property owners.  Decades of runoff and vegetation decay has robbed the storage capacity of lakes, ponds, and canals throughout the United States.  The Mini dredge is a compact, highly portable, gasoline engine powered sediment removal pumping system, designed to provide the homeowner and contractors with the ability to excavate and transfer unwanted sediment. It is an efficient alternative to machinery such as: back hoes, excavators, and drag lines. These methods of mechanical excavation are expensive, have limited reach, are destructive to the shore, and typically deposit the material adjacent to the shore only to wash back in with the first good rain.

Our dredges is particularly effective in removing sand, silt, and that fluffy black stinky mud that has ruined your ability to enjoy your waterfront. It is not possible for a dredge in this price range to excavate thousands of cubic yards of material in a short period of time. The excavation capability of these units are in the neighborhood of 10-30 cubic meters per hour depending upon: the nature of your sediment, distance pumped, and your energy & skill levels. To give you a point of reference, a pile of sand the size of a Ford F250 pickup truck would be about 15 cubic meters. That generally represents the size of a hole that you can make in an hour. 

Model PS-165-ER

If you are cleaning a modest area for example; around a dock or boat slip, you can expect to get the job done relatively quickly. On the other hand, if you have a large surface area to cover, say 1 hectare, you are going to be whittling away at it for awhile.  Using our pickup truck example again, if you dredge for 4 hours every other weekend for 6 months, you would be able to park a fleet of 50 trucks in the hole that you created. The intent here is to provide you with the means to diminish your sediment problem  with a quality, yet affordable piece of equipment. You are also going to have to be prepared to deal with the fact that you will be pumping a lot of water along with the sediment. The mud is not going to come out of your discharge hose looking like toothpaste. Even expensive industrial dredges can’t do that.  On the other hand, this unit will provide you with the means to renew  the quality of your waterfront, and the quantity of removed sediment will be limited only by the amount of time & energy that you put in to it.


What is the difference between the Mini dredge pump and cheaper engine driven self priming trash pumps? 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 50 years. We are very critical about quality, and we make our pumps as if we are building them for ourselves.

What is the difference between the Mini dredge and a gold mining dredge? 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 270 meters).

How far can the Mini dredge transfer sediment? 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 10 meters high dam, then down 6 meters vertical feet the other side of the dam, then your static head is 4 meters.

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 1 to 1.5 meters per second.  We prefer to utilize a more conservative value of 2 meters per second. The text book minimum velocity for sand is 1.5 to 2 meters per second.  Again, we prefer to utilize a more conservative value of 2.7 meters per second.

Velocity is defined by the flow in liters per minute, and the discharge hose diameter. 582 liters per minute through a 3" hose translates to 2 liters per second, the minimum velocity for transporting mud. 750 liters per minute represents 2.75 liters 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. 4.5 meters of static head is roughly equivalent to 30 meters of hose. Add 30 meters for every 4.5 meters of static head.  For example: you have 60 meters of actual discharge hose, and 9 meters of static head, then,  utilize the 120 meters discharge hose value in the left hand column. Your flow will be 750 liters per minute, velocity 3 liters per second (plenty for both sand and mud), and your dredging capabilities will be 14.5 cubic meters per hour for sand, 17 cubic meters for mud. If you phone 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 PS-135-E.

Discharge length in meters Flow liters per minute Velocity meters per second Sand cubic meters per hour Mud cubic meters per hour
15 1250 4.50 21.5 24.5
30 1150 4.25 20.0 23.0
60 1000 3.65 17.5 20.0
90 880 3.25 15.0 17.5
120 830 3.05 14.5 16.8
150 755 2.77 13.0 15.3
180 700 2.56 13.7
210 660 2.42 13.0
245 625 2.28 12.2

Piranha Pumps & Dredges
Ph.: +1 (505) 822-0449

+38 (050) 638-7576



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