Presentation on the topic of hydraulic machines in the Ministry of Emergency Situations. Hydraulic machines. Experimental Characteristics of a Centrifugal Pump

Goals and objectives of the lesson: To know: - the physical foundations of the design and operation of a hydraulic machine; - the concept of a hydraulic machine; - practical use hydraulic press; Be able to: - apply the acquired knowledge when conducting an experiment; - master the techniques of written and oral speech;

Mechanisms that operate with the help of some kind of liquid are called hydraulic (Greek "gidor" - water, liquid).

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Test The large piston is acted upon by a force N, and the small piston is acted upon by a force of 300 N. What gain in force does a hydraulic machine give?

Target: To study the physical basis of the operation and design of hydraulic machines.

Tasks:

Educational:

Apply existing knowledge to explain the operating principle of technical devices.
Create conditions for understanding the special properties of the operation of a hydraulic jack and press.

Developmental:

Create conditions for enhancing cognitive activity.
Develop students' abilities to express their thoughts correctly.

Educational:

To develop cognitive interest in the subject, to show the importance of physics for the development of technology.
Develop communication skills

During the classes

Checking homework

In previous lessons, we studied the pressure of solids, methods for calculating it, methods and the need in practice to increase or decrease this pressure. It was equally important to know how hydrostatic pressure is measured. Submarines, scuba divers, divers, etc. They are constantly under this enormous pressure. And finally, the pressure of gases and, above all, our atmosphere. After all, you and I live at the bottom of the air ocean and it is vitally important to monitor atmospheric pressure. In the previous lesson, we learned how to measure pressure, both greater than atmospheric pressure and pressure less than atmospheric pressure, which is equally important in technology. So we will show our knowledge on all these issues that have already been studied.

The topic of our lesson today is hydraulic machines.

(Slide 1).

Convert units of measurement mm.Hg. in Pa. (Slide 3)

Understanding many phenomena requires knowledge of one of most important laws nature - Pascal's law.

Who knows the formulation of Pascal's law, raise your hand.

We repeated to you:

1) How pressure is transmitted in a liquid.

All these 3 tasks are the main ones in the work of one of the most “strong” machines, which easily stamps bodies, fenders, doors of not only cars, but also trucks, does many, many hard jobs in agriculture, industry, and even in dad’s garage.

Who guessed what these cars are called?

Hydraulic machines.

First, let's see how they look on the model. (Appendix 3) (Appendix 2)

Who can describe its device?

A hydraulic press consists of two cylinders and freely moving pistons of different cross-sectional areas, connected by a tube filled with mineral oil. In their notebooks, students make a schematic diagram of a hydraulic machine, repeating the rule (algorithm) for describing the structure of the press. Presentation 1 (Slide 7)

Let F 1 be the force acting on a small piston with area S 1 . Then the pressure that the small piston produces on the liquid is equal to:

According to Pascal's law, this pressure is transmitted equally in all directions. Consequently, exactly the same pressure p 2 = p 1 is applied to the larger piston. Now you can calculate what pressure force acts on the larger piston: F 2 = p 2 S 2.

Let's carry out a simple calculation of the pressure force that the larger piston develops. It will provide a complete understanding of why this powerful machine was built. (The numbers are chosen to be effective and simple so that students can easily cope with the calculation of the gain in strength almost orally. Otherwise, behind the heavy calculations they will not be able to discern the essence of the matter).

The ratio F 2 /F 1 = S 2 /S 1 is called the gain in power.

Modern hydraulic presses make it possible to obtain a gain in strength of several thousand times.

Let's see how much force you need to act with to lift a car, a motorcycle, and find the mass with which various bodies will be balanced. Appendix 4

What conclusion can be drawn from this? Presentation 1 (slide 9)

Where are such devices used? (slide 11,12)

So, we got acquainted with the principle of operation, design and application of a hydraulic press. Now let's test ourselves what we learned in this lesson. ( Appendix 5)

Summing up lesson summary, children conclude that hydraulic mechanisms are necessary in human life.

They allow you to achieve gains in strength. Annex 1

Setting the price knock and announcement of homework.

Literature.

Peryshkin A.V. Physics 7th grade - M.: "Drofa", 2009.
Volkov V.A., Polyansky S.E. Lesson developments in physics, grade 7 - M.: "VAKO" 2009.
Peryshkin A.V. Collection of problems in physics grades 7-9 - M.: Publishing House "Exam" 2006.

During the classes.

I.Organizing time.

Purpose: to inform the topic of the lesson, formulate the goals of the lesson, get students ready for work.

Base repetition.

Questions:

Slides 1,2 . Oral answers to questions given on the slides.

Motivation and message of the lesson topic.

Teacher's word: A person, settling where there are no sources of water, is forced to organize its delivery to the place of residence and its purification. People need water not only for drinking, but also for watering agricultural land, hygiene procedures, extinguishing fires, etc. It is clear that even in a city on the banks of a river it is necessary to have devices that allow water to rise upward. The first such devices were simple lifts. It was with their help that water was mainly obtained from wells and reservoirs until the 18th century.

However, back in the 1st century. n. e. The ancient Greek scientist Heron from Alexandria described a fire pump invented by the ancient Greek mechanic Ctesibius (Slide3) This pump uses two pistons and four valves, through which water gradually fills the central cylinder of the pump under pressure. When the water level in the central cylinder reaches the hole, the water rushes out through a tube placed on the pipe extending from the hole and is directed to the fire. This pump was used by firefighters until the mid-20th century.

(Slide 4) Manual piston pumps, in which the piston creates a vacuum and atmospheric pressure supplies water under it, are still preserved today. garden plots. They have only one piston and two valves. Otherwise, their principle of operation is the same as in the ancient fire pump. A story about the design of a diaphragm pump on a slide. Piston pumps reached their heyday in the 19th century, when they began to use steel pistons driven by steam engines.

4). The development of electric power in the 20th century, the emergence of a variety of engines, from diesel to electric, the need to extract oil from deep wells - all this contributed to the invention of new types of pumps that make it possible to use the rotation of the engine shaft.

For example, gear, centrifugal, and diaphragm pumps are widely used. They allow you to lift liquids to a height of more than 10 m. For example, in the USA for pumping station Grand Coulee created a vertical single-stage centrifugal pump capable of delivering 138,000 m 3 /h to a height of 95 m. A distinctive feature of all these pumps is the acceleration of the incoming fluid to high speed.

A story about the design of a diaphragm pump on a slide (Slide 5)

Conception stage.

Purpose: to explain the principle of operation of hydraulic machines.

Other remarkable machines, the operating principle of which is based on Pascal's law, make it possible, with little effort, to achieve the influence of enormous forces on the desired objects.

Their design is simple: two communicating vessels with different base areas, in which the compressed liquid transfers the force of one piston to the other.

1. If on a piston with an area S 1 press hard F 1, then the pressure under the piston (slide 6) will be equal to

At the same level in the right vessel the pressure will also be equal p 1 ,. However, if the area of the right piston is equal to S 2, then the force of the liquid on the right piston will be equal to

Thus, if the right piston is 10 times larger in area than the left piston, then by applying a force of 1 N to the left piston, we can create a force on the right piston 10 times greater

2. As much liquid leaves the left half of the vessel, the same amount will arrive in the right half. Therefore, if we move the left piston by 10 cm, the right one will rise only 1 cm. To lift the bodies, they use a valve system and repeat the procedure of lowering and raising the left piston several times. The hydraulic jack works

Try to tell yourself from the slide how a hydraulic jack works.

3. If we place a stationary crossbar above the piston on the right, the load will rest against it, and we will squeeze it with great effort. This device is called a hydraulic press.

In serious technical devices Oil injection occurs not manually, but using a special engine.

Reflection stage.

Target: application of acquired knowledge in solving problems and answering questions.

It is necessary to formulate answers to the questions given on slides 6, 7 .

Summing up, grading.

TO non-mechanized hand tools include: fire hooks, crowbars, hooks, axes, carpenter's saws, scissors for cutting electrical wires. At the customer's request, the kit may include other tools, for example, hydraulic shears for cutting reinforcement.

Driven by an electric motor, internal combustion engine, compressed air, hydraulic unit; elastomeric pneumatic jacks, pneumatic plugs and pneumatic plasters.

Classification of tools

By type of drive:

manual non-mechanized firefighting tool: axe, hook, crowbar, hook, as well as a set of universal tools and a cutting device air lines power transmission and internal wiring;

manual mechanized firefighting tool with electric drive, motor drive, pneumatic drive, hydraulic drive.

By functional purpose:

Placement of tools and equipment on fire trucks

The placement of the software must satisfy a number of requirements: help reduce PA, not reduce its operational mobility, its fastening and placement must be injury-proof.

To implement the stated requirements, the placement of software in the PA compartments must obey the principle of ergonomics, according to which equipment, controls and devices must be located in accordance with the logic of human activity.

When placing software in AC compartments, the following possibilities should be taken into account:

Hand-held non-mechanized tools: crowbars, hooks, hooks, axes, saws, shovels, scissors for cutting metal gratings, a set for cutting electrical wires (scissors, rubber mat, boots, rubber gloves, portable grounding), a set of fireman's hand-held non-mechanized tools UKI-12, hand rescue tool IRAS.

Manual non-mechanized firefighting tools include: fire crowbars, hooks, axes, hooks, shovels, saws and a set of tools for cutting electrical wires.

Fire hooks are designed for dismantling roofs, walls, partitions, rafters and other parts of building structures and pulling away flammable materials. There are two types of hooks used in fires.

Metal fire hook (FPM) consists of a hook, a spear, a metal rod and a handle. The rod is made of a pipe with a diameter of 20 mm. The hook and spear are made of St45 steel and are subjected to heat treatment. The hook and metal ring are welded to the rod. Fire trucks are equipped with these hooks. RICE.

Fire crowbars are designed for opening building structures and are included in the set of fire trucks.

(LPT) Designed for heavy lever work on opening structures with tight joints (floors, plank trusses, partitions), as well as for opening doors.

The crowbar is a metal rod with a diameter of 28 mm. Its upper part is curved and forms a tetrahedral hook, and on the lower part there is a sharpening for two edges.

Fire scrap PSh with a ball head is designed for covering plaster and chipping ice from hydrant well covers.

The crowbar is a round rod with a ball at the upper end. Its diameter is 50 mm, the flat cut has a diameter of 25 mm. At the lower end of the crowbar there is a sharpening for two edges with a blade width of 12.5 mm.

Fireman's light crowbar (LPL) used for clearing fire sites, opening roofs, sheathing and other similar work.

It is a metal rod with a diameter of 25 mm, the upper end of which is bent at an angle of 450 and sharpened into four edges so that a flat blade 10 mm wide is formed. The sharpening length is 80. The lower end of the crowbar is also tetrahedral. At a distance of 200 mm from the upper end there is a ring with a diameter of 30 mm for hanging it.

Universal fireman's crowbar used to open windows and doors. It is a metal rod with two bent parts.

Crowbars are made of St45 steel, their pointed parts are subjected to heat treatment.

IN fire department a hook for opening the covers of hydrant wells and a lightweight fire hook are used. Fire hooks are included with fire trucks.

Lightweight fire hook (LPH) designed to open structures inside buildings and remove them from the fire site. The hook is made of strip steel St45N, with a section of 25x12 mm. Hook length 395 mm, width 225 mm. The upper end of the hook is sharpened into two ends, and the lower end ends with an eyelet for tying a rope 14...17 mm thick and 1300 mm long. The rope ends in a loop 500 mm long. Hook weight 1.5 kg.

The fireman's belt ax has a blade and a pick. Its blade is designed for dismantling wooden structures. The pick is used to make holes in brick and concrete structures and to move firefighters along roof slopes.

The ax blade is made of high-carbon steel U7, and its blade is subjected to heat treatment. The ax is mounted on a wooden ax handle and secured to it with metal plates. The ax handle is made from hard wood (birch, maple, ash, hornbeam, beech). The ax handle is not painted, because paint may cover surface cracks. The length of the ax is 350...380 mm, and its weight should be no more than 1 kg.

Fire shovel. A shovel is one of the types of fire equipment. Used for extinguishing small ground fires and submission fire extinguishing agents to the source of ignition.

There are two types of fire shovels:

A bayonet shovel is used to localize or extinguish small fires.

Weight: no more than 2 kg

Overall dimensions: 1500x230x170 mm

A shovel is designed to supply sand to the source of fire.

Weight: no more than 2 kg

Designed for opening and dismantling building structures when extinguishing fires. The kit includes: two universal rods with retractable handles and a set of replaceable working parts. The universal rod has locking devices for fastening the handle in two positions and installing one of the working parts.

Technical characteristics of UKI-12M:

Maximum bending moment, Nm – 785;
Maximum tensile force, N – 1960;
Duration of replacement of working parts, s – 10;
Time for cutting a hole with a diameter of 500 mm in a sheet of roofing iron up to 0.8 mm thick, s – 180;
Weight of universal rod with hook handle, kg – 5.3;
Weight of the kit in the container, kg – 28.0;
Overall dimensions of the container with the tool, mm – 1000x295x270;
Service life, years – 11.

Technical characteristics of IRAS:

The maximum bending moment on the head handle is 220 Nm.
The maximum bending moment on the opener rod is 160 Nm.
Total weight – 5.0 kg.
The weight of the multi-purpose head is 3.15 kg.
The weight of the opener is 1.82 kg.
The length of the tool with the opener extended is 825 mm.
Overall dimensions – 570x67x200 mm.
Service life – 6 years.

Manual power tool, classification by drive type

Types of hand-held power tools depending on the drive:

from an internal combustion engine (gasoline);
from an electric motor (electric);
from compressed air (pneumatic)
from a hydraulic unit or hand pump (hydraulic).

Portable smoke exhauster DPE-7 with electric drive
Console type chain saw

Elastomeric pneumatic jacks;
Elastomeric pneumatic plasters;
Pneumatic jackhammers (concrete breakers)

Hydraulic scissors (cutters);
Hydraulic spreaders;
Combined hydraulic tool;
Hydraulic jacks;
Devices for opening metal doors;
Hydraulic drive devices (hand pumps and pumping units);
Hydraulic impact wrenches;
Hydraulic pipe clamps.

and "Bear". Types, purpose, device and brief technical characteristics, scope and procedure of application.

Hydraulic rescue tool (HASI) “SPRUT” is:

high power characteristics with small weight and dimensions;
simplicity and ease of operation and maintenance;
multifunctionality;
high operational reliability, possibility of use in different climatic conditions and etc.

Fig.1. Nippers KGS – 80Х

Designed for cutting sheet metal, pipes, profiles, cutting fittings.

Fig.2. Combined scissors KNKGS – 80

Used for cutting metal, pipes, cutting steel fittings, as well as for moving, lifting and holding loads in a fixed position

Fig.3. Large expander KRBGS – 80

It is used to move various objects, make passages in rubble, and widen cracks at the junction of objects that are difficult to move apart. For holding loads in a fixed position, deforming and tightening

Fig.4. Hydraulic wedge jack DKG – 80

It is used for pressing out steel doors, pipeline flanges, and widening cracks where the lack of gaps does not allow the use of other tools.

Fig.7. Drum extension KKUS – 1/15

Used in conjunction with a hydraulic station to increase the working area of hydraulic tools

Manual pump RN 2080M designed to supply working fluid to a hydraulic tool. Operated by the operator's hand. Can be used in explosion and fire hazardous areas, mines. Equipped with high-pressure hoses 3 or 6 meters long.

Operating pressure	80.0 MPa
Pump type	two-stage
Useful volume of working fluid	2000 cm3
Weight of the pump ready for operation	11.9 kg
Working volume for each stroke, not less than:
- first stage	20.4 cm3
- second stage	2.25 cm3
Dimensions:
- length	740 mm
- width	220 mm
- height	176 mm

Extension reel KU2080-1/10M designed for supplying working fluid from a pumping station or hand pump to a hydraulic tool, transporting and storing hoses. Is integral part emergency rescue portable tool with hydraulic drive.

Combined scissors NK2080M designed for widening narrow openings, lifting, moving and holding objects stationary, biting and cutting steel bars, angles and other profiles, compressing pipes. Can be used in conjunction with the NP 2080M accessory set. Equipped with hydraulic locks.

Universal cutter RU2080M designed for biting and cutting steel bars, pipes, angles, various profiles, ropes and cables during emergency rescue operations in areas emergency situations, transport accidents, disasters, fires, natural Disasters, as well as during construction and installation and dismantling work in various industries.

Requirements of technical regulations on fire safety requirements for fire-fighting tools

A firefighting tool, depending on its functional purpose, must ensure the following:

work on cutting, lifting, moving and fixing various building structures;
work on punching holes and openings, crushing building structures and materials;
work on plugging holes in pipes various diameters, sealing holes in tanks and pipelines.

Hand-held power tools must be equipped with safety devices that prevent parts of the human body or clothing from accidentally falling into the moving mechanisms. Controls of mechanized fire-fighting equipment must be equipped with signs that prevent ambiguous interpretation of the information posted on them.

The design of mechanized and non-mechanized firefighting tools must provide the ability to quickly replace working elements.

The design of the fire-fighting tool's docking units must ensure quick and reliable connection manually without the use of keys or other plumbing tools.

The design of the firefighting tool must ensure the electrical safety of the operator during rescue operations.

Requirements of labor safety rules when working with hand-held fire tools

Firefighting tools and equipment (crowbars, hooks, hooks, shovels, axes, saws) must have a shape and weight that meets ergonomic requirements and meet the requirements of technical specifications and safety measures defined by the NPB.

The durability of the tool (equipment) and the safety of working with it is ensured by maintenance in good condition and timely technical maintenance. The suitability of the tool (equipment) is determined by external inspection and testing. In order to prevent accidents when working with a tool (equipment), when inspecting it, you should pay attention to the quality of the tool attachment on the handles and the cleanliness of the working surfaces. Axes, saws, and scissors for cutting metal gratings should be stored in cases.

The metal parts of axes and hooks must be securely attached to the handles. The strength of the nozzle should be set to standard and technical conditions for instruments of a specific type. Wooden handles must be made of durable wood and have no signs of damage, knots, cracks or chips. It is prohibited to paint the wooden surfaces of tools and equipment.

Familiarization with the placement of tools on fire trucks

The placement of the tool must satisfy a number of requirements:

Firstly, some of the equipment must be placed, if possible, in the crew cabin. This is necessary so that already when the combat crew goes to the fire, it can prepare to carry out the combat mission. Such equipment includes an oxygen-isolating gas mask and flashlights.

Secondly, the placement of equipment in body compartments should be subject to the need for minimal time spent on combat deployment.

Rice. 13. Placement of fire equipment in bodies and cabins fire tanker ATs-40 (131)-137:

1 - fire extinguisher OU-2; 2 - driver's tool; 3 - wrench 41-50: 4 - fire hose 77 mm; 5 - fire trunk SVP-4; 6 - fire hose 0 6b mm; 7 - fire column; 8 - three-way branching: 9 - hook; 10 - suction mesh; 11 - sleeve clamp; 12 - transition head GSP-50X80; 13 - transition head GSP-70X80; 14 - fire nozzle PC; 15 - RSK fire trunk; 16 - hose for foam concentrate; 17 - linen pressure fire hose 51 mm; IS - partner fire hose 0 51 mm; 19 - water collector

Literature:

Textbook for higher educational institutions Ministry of Emergency Situations of Russia M.D. Bezborodko, S.G. Tsarichenko, V.V. Roenko, N.I. Ulyanov, M.V. Aleshkov, A.V. Rozhkov, A.V. Ploskonosov, S.A. Shkunov, V.M. Klimovtsov, S.P. Khramtsov “Fire and rescue equipment” Moscow 2012.
Fire equipment. Tool for special work on fires. Are common technical requirements. Test methods On approval of occupational safety rules in departments of the federal fire service State Fire Service

Machines using liquid as a working medium. Divided into pumps and hydraulic motors.

Pump - communicates the flow of fluid mechanical energy, receiving it from the drive motor

Hydraulic motor - receives energy from the flow of working fluid and converts it into the energy of movement of the output link, transferring it to the working parts of the machine.

If the output link receives rotational motion, then such a hydraulic motor is called a hydraulic motor, if it is translational, then power cylinder.

According to the principle of operation, hydraulic machines are divided into volumetric and dynamic

I mean volumetric hydraulic machines, the working process of which is based on alternately filling the working chambers with liquid and displacing it from these chambers.

The main type of dynamic pumps are vane pumps

Vane machines have a rotating impeller equipped with blades.

Blade machines

The working body of a blade machine is a rotating impeller equipped with blades.

Energy from the fluid impeller is transferred through the dynamic interaction of the impeller blades with the fluid flowing around them

IN centrifugal vane pump The liquid, under the influence of centrifugal forces, moves through the impeller from the center to the periphery.

The flow part of the pump consists of three main elements - inlet 1, impeller 2 and outlet 3. Through the inlet, liquid is supplied to the impeller from the supply pipeline. Impeller 2 transfers energy to the fluid from the drive motor.

IN axial vane pump the liquid moves mainly along the axis of rotation of the impeller. The impeller of an axial pump is similar to a ship's propeller.

It consists of a sleeve 1 on which several blades 2 are attached. The outlet of the pump is an axial guide device 3, with the help of which swirling of the liquid is eliminated, and its kinetic energy is converted into pressure energy. Axial pumps are used for high flows and low pressures.

In an axial pump, you can expand the range of working flows and pressures in which the pump operates by using rotary blades.

With a change in the angle of installation of the blade, the pump characteristic changes greatly with a slight decrease in the optimal efficiency

Fluid movement in the impeller of a centrifugal pump

The speed of absolute movement V (absolute speed) is equal to the geometric sum of the speed W of the fluid relative to the impeller (relative speed) and the peripheral speed U of the impeller (transfer speed)

The angle between the absolute V and the portable velocity U of the liquid; - the angle between the relative speed W and the negative direction of the portable velocity U of the liquid.

V U - projection of absolute speed onto the circumferential direction

Flow, pressure, pump power and efficiency

Pump flow is the flow rate of fluid through the discharge port.

Pressure H is the difference in the specific energy of the liquid in the flow section after the pump and in front of it. This is the specific energy that the pump imparts to the fluid.

H Z H Z B PH g P V 2 2 g V 2

Where the indices indicate H - pressure, B - suction.

In geometric interpretation, this is the height to which the liquid is able to rise under the influence of static pressure and the difference in speed at the inlet and outlet of the pump.

Pump power(power consumed by the pump) is the energy supplied to it from the engine per unit of time.

Net power of the pump N P power supplied by the pump to the pumped liquid.

Determined by the formula: N P = gHQ.

Energy balance in a vane pump

Mechanical losses-- friction losses in bearings, shaft seals and friction of the outer surface of the impellers against the liquid.

The remaining power minus mechanical losses is transmitted by the fluid impeller. It is usually called hydraulic N Г.

Volume losses.

The liquid leaving the impeller mainly enters the pressure pipe of the pump, and partially returns to the supply through the gap in seal 1 between the impeller and the pump body.

The energy of the fluid returning to the inlet is lost. These losses are called volumetric losses.

Hydraulic losses

They are spent to overcome the hydraulic resistance of the inlet, impeller and outlet.

Г hydraulic efficiency, taking into account power losses to overcome hydraulic resistance in the pump; o volumetric efficiency, taking into account power losses in the pump due to internal

leaks, flow of liquid through gaps from a cavity with high pressure into a cavity with low pressure;

mech mechanical efficiency, taking into account power losses in bearings, seals and friction of the outer surface of the impeller with the liquid.

N N P

Basic Equation of Vane Pumps

The basic equation for vane pumps was first derived by Euler.

It relates the pump head to the fluid speeds, which depend on the pump flow and rotation speed, as well as on the geometry of the impeller and supply.

The theoretical head created by a centrifugal pump with an infinite number of blades (z=) is equal to

H T g 1 u 2 2u u 1 1u

where u 2 and u 1 are the peripheral speeds of the impeller at the outlet and inlet;

1U and 2U circumferential components of absolute speeds at the exit and entrance to the wheel.

The actual pressure of a centrifugal pump is equal to

H n g k z H T

Here k is the influence coefficient of the number of blades,

2sin 2

which can be estimated by the following approximate

Experimental Characteristics of a Centrifugal Pump

The characteristic of a pump is the dependence of pressure, power, efficiency and suction head on flow.

Cavitation and cavitation reserve in hydraulic machines

Cavitation is a violation of the continuity of liquid flow caused by the appearance of bubbles filled with gas or steam. Cavitation occurs when the pressure decreases, causing the liquid to boil or release dissolved gas. In most cases, gas evolution does not play a significant role.

In a fluid flow, pressure drop usually occurs in the region of high velocities. When a liquid moves in an area of high pressure, the vapors in the bubble condense and collapse, during which the liquid particles move inside the bubble and collide with each other.

This leads to an instantaneous local increase in pressure reaching thousands of atmospheres. There is erosive destruction of the canal walls.

In vane pumps, cavitation is accompanied by a drop in flow, pressure, power and occurs on the impeller blade near its inlet edge.

The pressure here is significantly lower than the pressure in the pump inlet due to a local increase in speed and hydraulic losses in the supply.

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