While most water pumps are fairly quiet during operation, hydraulic drive motors can be quite noisy. Ensure that the noise you hear is in fact coming from the water pump. If the pump is making a growling, grinding, squealing, or popping noise, it should be immediately disassembled and inspected for damage.

There could be several factors behind this:
 
Is there enough water? Check to ensure that there is enough water present in the tank to allow safe pumping; the Mega Digital Spray Control System shuts the water pump once a sufficiently low water level has been reached.

Beware of air locks. If there is too little water in the tank, the pump may have drawn in a large air pocket that is preventing the flow of water (see What is an air lock? question below).
Is the lift displacement too great? If you are operating a suction lift pump, be sure that the water reservoir you are drawing from is no more than 7 feet below the pump, otherwise the resistance to flow may be too great.

Are you using pipes that are too small or have too many elbows? Pumping water through small diameter pipes (and pipes with elbows and check valves) increases the water pressure, but as a result also increases flow resistance. If the resistance is too great, your pump will not perform.

Absolutely,the water pump shaft and impeller are spinning at extremely fast rates. With no water to transfer their rotational energy to, that energy is released as heat instead. If the pump is run dry, its moving parts will become extremely hot, causing severe damage to the pump over time and greatly limiting its service life.

When the inlet pressure of a water pump falls below pump design specifications, tiny vapor bubbles can form in the water around the eye of the impeller. When the water containing these bubbles is forced into a high pressure environment on the other side of the impeller, these bubbles collapse, thereby creating tiny shock waves and points of high temperature. These shock waves can actually corrode the surface of the impeller. To prevent cavitation, always be sure to operate your water pump within its pressure and flow specifications.

Any time that the water pump is serviced and the gaskets are removed, replace the gaskets.

Water pressure is caused by resistance to flow. If a force tries to move water and there is resistance to that movement, then the water becomes pressurized. Consider a standard garden hose; when the end of the hose is unrestricted, water flows out of the hose in large quantities, but without much force. If you press your thumb over the opening, however, the stream of water that shoots out from around your thumb will be much more forceful and will travel further, but there will also be less water per second leaving the hose.

Centrifugal water pumps use centrifugal force to pressurize and move water from the inlet to the outlet. A rotating set of vanes (called an 'impeller') is spun by the pump shaft. As water is forced through the impeller, rotational energy is transferred from the impeller to the water, which gains velocity and pressure through the centrifugal force applied and is flung from the impeller. The volute (a spiral-shaped case) funnels the now-pressurized water to the outlet.

Gear pumps are usually configured with inlet/outlet ports in the same plane.
We define the locations as follows: side, deck, face ports.
Pumps with moulded ports and/or Diener-supplied port fittings are sized for optimum pump performance. We recommend that customer-supplied fittings be carefully sized and applied to avoid the following problems:
1. The inside diameter of the fittings should be large enough to minimise the chance of cavitation.
2. Tapered pipe thread fittings should be used with a liquid thread sealant or Teflon tape.
3. Parallel pipe fittings should include a shoulder O-ring or thread sealant.
4. Plastic tube fittings swell with increasing temperature, so select them carefully if operating across a wide temperature range.

Gear Pumps:The gear pumps can mounted in any plane, although positioning it so that the outlet is straight up will reduce priming time.
Avoid mounting pump with the motor below the pump because although the pump is magnetically coupled and thus “leak proof”, fittings and/or tubing going into the pump may break and flow down into the motor.

Piston Pumps:To eliminate trapped air, the preferred orientation is with the outlet of the pump facing straight up. Because piston pumps have a shaft seal, the pump should be mounted so that the motor axis is always at or above the axis of the piston.

The life expectancy of a pump will depend on the operating conditions. These include such things as fluid type, temperature, differential pressure, contaminants, and motor speed. Careful selection of the wetted components will help minimize wear without compromising performance.

The Piston pump series of FYT-Pumps are constructed of ceramic and typically last for the life of the equipment, depending on the accuracy requirement. Piston pump life is generally measured in number of cycles (strokes).

Gear pump life is more likely measured in hours, since they are typically used in continuous operation. Designing the bearings so that they stay within the pressure-velocity limits of the polymers is the key to longevity. The new Silencer series by YT-Pumps operated for 30,000 hours pumping distilled water with no drop in performance. This represents a continuous life expectancy of 3-1/2 years.

Some gear pumps of Pumps are fitted with adjustable internal relief valves. These serve two purposes: (1) to prevent over-pressurisation and (2) to prevent magnet decoupling. The valve is adjustable via an external screw adjustment. Pumps are provided with the valve completely closed so the customer can fine-tune its position during final installation. Caution: do not over-tighten the adjustment screw as it may damage the internal components.

Filtering the fluid before it enters the pump is always recommended, although filters must be chosen and maintained carefully to prevent cavitation. Our Pumps recommends a maximum filter size of 40 micrometres for gear pumps and 2 micrometres for piston pumps. The pumps will pass particles larger than this, but with increasing particle size becomes the potential to damage the pump. Never pump fluids with ferrous particles (iron, steel) through magnetically coupled pumps because the particles can stick to the magnet.
Diener developed a gear pump product line specifically designed to pump fluids with suspended particulates, especially pigmented inks and paints. The gears in these pumps are specifically hardened for this purpose but require engineering review depending on the fluid type and pigment loading. Please consult our factory for application assistance.

The moving components in a positive displacement pumps are typically machined to very small clearances. Once these clearances are filled with fluid, the viscous shear (see Viscosity section) acts to seal the surface and increase the pump’s volumetric efficiency. When the pump is first installed in a system (and presumably dry), the surfaces are not sealed and thus air in the lines can easily get through the spaces. The pumps ability to prime itself is called its “dry lift” capability, usually expressed in mmHg or meters of H2O. The smaller the clearance between moving parts, the higher the dry lift value. Once the pump surfaces are wetted, even with just a thin layer of fluid, the clearances seal better and result in its “wet lift” capability. Positive displacement pumps always have higher wet lift values, so priming the pump prior to start-up is always beneficial: it reduces start-up response time, reduces dry friction, and lengthens pump life.

The pumps of Pumps are designed to run “dry” for short periods until they self-prime. However, operating a gear or piston pump “dry” for extended periods is not recommended because it generates frictional heat that can damage pumps. The limits are shown on each product datasheet.
A word of caution: starting a gear pump completely dry causes a very loud noise. We always recommend putting a small amount of fluid into the pump prior to start-up (just enough to wet the interior surfaces).

The volume of fluid contained within the pump is referred to as the “dead volume”. The dead volume of a piston pump is normally measured with the piston fully retracted. Minimising this volume helps reduce cleaning time and fluids cost. In some pumps from Pumps, we’ve included a “quick rinse” feature that routes the fluid through the magnetic coupling area to further reduce cleaning time.

Cavitation is a common problem in pumps, caused when local fluid pressures drop below the fluid’s vapour pressure. In general, pump cavitation occurs when the inlet pressures are low. For example, if there is a blocked filter on the inlet, the pump tries to pull fluid, lowering the pressure to overcome the restriction. If the pressure continues to drop (i.e., form a vacuum) the fluid boils and forms vapour bubbles that collapse, damaging the surfaces.
Symptoms of cavitation include high noise, vibration, and unstable motor speed. The noise and vibration come from the collapsing bubbles and the motor speed becomes unstable due to the uneven torque loading. Confirmation of the problem is checked by measuring the absolute pressure at the pump inlet.
Fortunately cavitation is preventable. Correct pump sizing is critical, as is design of the inlet/outlet tubing and fittings. Coarse filters are acceptable on the inlet, but fine filters should be avoided because they can plug quickly and form restrictions. Avoid small diameter fittings and long lengths of small I.D. tubing. In general, size components so that the pump can “breathe” easily and remember to increase tube and fitting I.D. for higher viscosity fluids.
The piston pumps inlet stroke of TOPSFLO Pumps occurs over only 90 degrees of rotation of the piston, so the fluid momentum is accelerating and decelerating quickly. It’s important to size the inlet tubing sufficiently large to allow the full flow through. It’s good practice to oversize the tube cross-sectional area to account for this.