For understanding the role of fine abrasive fluid in positive displacement let’s start from the beginning and introduction to the same.
Fine abrasive fluid
The fine abrasive fluid enhances the wear in a pump by disintegrating the surfaces by contact force or stimulation of a chemical reaction. The same is considered as one of the finely detailed refractory materials. The disintegration (wear) is done by the fluidic medium, thus, making the size and role of solid components in the fine abrasive fluid important. These may include suspensions of carbon, pigments found in paints, pigments, or finer metals, etc. The abrasive fluid’s viscosity affects the overall usability of the product as in the case of external gear pump. Such pumps are one of the common rotary ones. These are the ones in which ceramic gears aren’t used due to the chances of brittle breakage as a result of sharper corners. Liquids with high abrasive properties may result in a grinding-scratchy sound.
Positive displacement pumps
The pumps enhance the quality of displacement of the entangled fluid volume positively, by the process of suction and expansion of the inlet, at the time of outlet contraction. The nature and working of positive displacement pumps vary when compared to the centrifugal ones as when the latter one reaches high rates of flow, they become sensitive to pressure. On the other hand, the positive displacement pumps have fixed volume per revolution and thus theoretically work free from the outlet, inlet pressure, or respective properties.
These pumps are specialised in pumping the fine abrasive fluid by producing high pressure. Though these don’t use impellers but are often referred to as constant flow devices. These are also called Reciprocating pumps.
Fine abrasive fluid and positive displacement: The relation
The abrasive particles embed themselves in the packing, to accelerate the wear in the shaft. The wise selection matters a lot in improvising the movement of the fluids. Positive displacement pumps are specially designed to handle fine abrasive fluids and aren’t cataloged to low speed.
Keeping the differential pressure low, is an important factor considered for the successful application of PD to the abrasive particles. The fluid viscosity, response, and density determine the positive displacement outcome of the respective pumps.
In dual precision series pumps, the suction is carried out by the piston, and suction and expulsion result together. These consist of a piston in both the fluid displacing sides. Gear pumps are lubricated by the pumped with highly viscous fluids to enhance the susceptibility to wear while using the abrasive fluids. The finer particles reduce the wear and thus ensures better positive displacement.
Abrasion causes uneven wear that works in accordance with the pump mechanism. Fine abrasive fluids are even a catastrophe to sliding seals. For the selection of the appropriate abrasive fluid, the type of pump is extremely important.
On the whole, the size of particles in the abrasive fluids affects the choice of the pumps. The finer the solid particles the better is the positive displacement of the pumps. Repeated and precise fluid dosing can be easily worked by the positive displacement or PD.