How do you control pump cavitation?

How do you control pump cavitation?

Some tips to prevent cavitation due to vaporization include:

1. NPSHa > NPSHr + 3 ft or more safety margin.
2. Lower temperature.
3. Raise liquid level in suction vessel.
4. Change out pump type.
5. Reduce motor RPM.
6. Use impeller inducer.
7. Increase diameter of the eye of impeller.

How cavitation occurs in pump?

Cavitation occurs when the liquid in a pump turns to a vapor at low pressure. It occurs because there is not enough pressure at the suction end of the pump, or insufficient Net Positive Suction Head available (NPSHa). As the liquid passes from the suction side of the impeller to the delivery side, the bubbles implode.

How does centrifugal pump prevent cavitation?

To avoid cavitation, the pressure of the fluid must be maintained above its vapour pressure at all points as it passes through the pump. Manufacturers of centrifugal pumps specify a property referred to as the Net Positive Suction Head Required or NPSH-R – this is the minimum recommended fluid inlet pressure.

How can we prevent cavitation in reciprocating pump?

Ways to avoid cavitation in reciprocating pumps:

1. Design: Ensure that there are no sharp corners or curvatures of flow in the system while designing the pump.
2. Material: Cavitation resistant materials like Bronze or Nickel can be used.
3. Model Testing: Before manufacturing, a scaled down model should be tested.

Why should we avoid cavitation?

The real problem is cavitation, which is caused when bubbles form and implode in pump systems, sending hot streams of water rocketing toward parts that can cause physical damage and render a pump useless. Avoid suction strainers. Suction strainers are intended to prevent hydraulic pumps from ingesting dirt and grime.

What causes cavitation in cooling system?

An increase in air bubbles in a cooling system can increase the potential for cavitation erosion (pitting) of metal surfaces. Increased air can enter the cooling system through cooling system leaks and/or a faulty radiator cap.

How cavitation can be avoided in reaction turbine?

The cavitation in reaction turbines can be avoided to a great extent by using the following methods: (a) By installing the turbine below the tail race level. (b) By using stainless steel runner of the turbine. (d) By running the turbine runner to the designed speed.

Why is draft tube used in reaction turbine?

Draft Tube is a diverging tube fitted at the exit of runner of turbine and used to utilize the kinetic energy available with water at the exit of runner. This draft tube at the end of the turbine increases the pressure of the exiting fluid at the expense of its velocity.

Where are draft tube used?

The draft tube is a conduit which connects the runner exit to the tail race where the water is being finally discharged from the turbine. The primary function of the draft tube is to reduce the velocity of the discharged water to minimize the loss of kinetic energy at the outlet.

What happens if a pump is oversized?

An oversized pump can cause excessive noise and vibration of pipes which over time can loosen flanged connections and joints as well as cause fatigue of pipe welds. This can lead to premature wear and failure.

What causes a pump to trip on overload?

Pump overloading occurs in centrifugal pumps when the driving motor draws excess current resulting in excess then normal power consumption. Thus, when the system resistance to the pump drops, more and more liquid is pumped resulting in increased power consumption.

Why is my sewage pump tripping the breaker?

The sewage pump could be tripping the breaker due to these few reasons: the impeller or volute is clogged, if this is the case, please remove pump and clean thoroughly or the fuse size or circuit breaker is too small, must be at least 15 amps.

How do you protect a pump from overload burden?

To avoid overload, control the speed of the primover of the pump to meet the design specific speed. 2. Higher viscosity of pumped liquid:- When the viscosity of the pumped liquid increases the brake horse power increases PH(K.w.)=(Q*g*H*γ)/(3.6×106).

What causes a motor to draw higher than normal amps?

Electrical overload or over-current is caused by an excessive current flow within the motor windings, exceeding the design current which the motor is able to carry efficiently and safely. This can be caused by a low supply voltage, resulting in the motor drawing in more current in an attempt to maintain its torque.

What is pump trip?

Pumps may encounter several situations where the motor or driver will be turned off purposely (pump shutdown) or unplanned (loss of power). This is known as a pump trip and is important to understand how this will impact hydraulic systems because it can lead to waterhammer.

Why does a motor trip?

Electric motor tripping reasons and how to fix them- The electric motor tripping may be due to a couple reasons, it may be due to the circuit overloads, short circuits, ground fault surges, low resistance, over-heating, contamination, vibration, cable/wire is cut, due to the motor direction clockwise or anti-clockwise.

Why does a water pump trip?

If the pump or pumps(?) are drawing more current than the capacity of the breaker and both pumps work together at same time it could trip the breaker. A short circuit in the pump typically caused by a failed mechanical seal can cause water to get into the windings and thus trip thw breaker.

What causes electric motor trip?

Causes may include a large change in load (e.g., a scrap grinder is fed too much at a time), misalignment, a broken drive gear, or improper motor drive settings. Power problems (e.g., low voltage or low power factor) also may cause an overload condition. It’s easy enough to determine the correct size overloads.

How do you protect an overloaded motor?

Motor overload protection is necessary to protect the motor and to help ensure the motor performs as expected. Continuous duty motors are protected against overload by a separate overload device sized between 115% and 125% of the motor nameplate full-load current, FLA.