Causes of leakage of low temperature solenoid operated hydraulic control valve

Low temperature solenoid directional valve is widely used in natural gas, liquefied gas pipeline, and its role as same to other varieties of solenoid operated hydraulic control valve are as for the normal transport of the gas medium in the pipeline, necessary to cut off and the role of regulation on the flow. The low temperature solenoid operated hydraulic control valve is used in a number of highly flammable gas pipeline, so in the connection of the pipeline, need to ensure that the gas will not leak. The main reason of low temperature solenoid valve leakage is:

There are two reasons for the leakage of low temperature solenoid operated hydraulic control valve, firstly the main reasons is the seal deformation in the low temperature state. When the temperature of the medium is decreased, the volume change is caused by the phase change of the material, and the sealing surface with high grinding precision is produced to cause warpage, leading to the bad sealing. Two is the external leakage. It is mainly due to the flange connection between low temperature solenoid valve and pipe, due to the connection pad, connecting bolts, and the connection between the material at low temperature shrinkage caused by the relaxation of the gap and lead to leakage. Therefore, the connection mode between the valve body and the pipeline can be changed to the welding structure, then the low temperature leakage can be avoided. Another is the stem and packing leakage. These are the main reasons for the leakage of low temperature solenoid operated hydraulic control valve.

BSTIND 4WE6 Directional Valves

Working pressure of rexroth 4WE6 Directional Valves is 32Mpa,the same as NG3 valve and Cetop3 valve. 4WE6 directional valve are usually used for changing the oil flow direction of hydraulic power,hydraulic working system and industrial hydraulic system.
4/3, 4/2 4we rexroth Type WE directional valves take use of wet-pin DC or AC voltage solenoids.
Size 6 Hydraulic Solenoid Valve
Component series is 6X (60~69)
The maximum operating pressure is 350 bar
The maximum flow is 80 l/min-DC Voltage Solenoids.
60 l/min using AC Voltage solenoids.

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The reason of hydraulic solenoid valve seal is not tight

Hydraulic solenoid valve does not seal tightly mainly has the following several aspects:

1.Elastic sealing material. The elastic sealing material according to the different media for supporting the design, this is not a problem, such as PTFE, EPDM, FKM, but the price gap is large, of course, here refers to the purity of the monomer which material proportion of more than 95%, most of them are refurbished material, the purity is not enough, and there is no guarantee that the chemical and physical properties will change, which is easy to lead to long-term dissolution of the medium with the media leakage.
2.Flexible sealing processing accuracy. The machining accuracy for miniature solenoid valve control precision and the elastic component of it, but if it is large diameter solenoid valve elastic shape of the component is not small, water, etc. will shrink, gate product flatness, roughness directly affects the current, abroad are integral forming, laser cutting, so that forming. Of course, this set of processing equipment investment is huge, the general factory can not do this. Since it is not smooth, it is easy to leak.

3.Machining precision of metal sealing contact surface and structural design. Of course, we can not say which design is best, can only be used in conjunction with the use of their elastic components, but the accuracy must be required, how much is the roughness, and what kind of material processing on such small contact end face? If the design of the end face is too large, will impact the flow rate, and it is easy to stuck crystal, dust and other fine particles on the elastic components, so it is easy to cause leakage, and will be more after a long time. But the cone seal design will not be such a problem, the contact surface is small, the flow rate is quick, but the flow will be very big in this kind of structure.

4.Plunger assembly welding. The general shape of the plunger assembly is small, the requirements of argon arc welding and laser welding are relatively high, one is to ensure the production capacity, but also to ensure the quality, this material is also relatively high demand, corrosion and oxidation medium will lead to weld point corrosion, has great influence on the air tightness.

BSTIND 4WE10 Rexroth Hydraulic Valves

Standard flow of 4WE10 bosch rexroth hydraulic Valves is 120l/m,and working pressure of hydraulic direction valve is 32Mpa,the same as NG5 valve and Cetop5 valve. 4WE10 rexroth type directional valve usually used on hydraulic power,hydraulic work system and industrial hydraulic equipment.

4/3, 4/2 directional valve with wet-pin DC or AC voltage solenoids
Size 4WE10 has Hydraulic Solenoid Valve
Component series has 3X (30~39),4X (40~49)
The maximum operating pressure is 315 bar
The maximum flow is 120 l/min

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Tile machine function

1.Tile pressure machine must use high pulse input function, high input of excellent performance, strong anti-interference ability of AB phase. And the use of fixed value interrupt function to ensure accuracy.
2.The detection part of the tile press machine: pulse encoder for detecting color steel tile length, the up and down switch of tile pressing, the up and down switch of cutter, the up and down operation button of tile pressing, the up and down button of cutter, emergency stop switch, hydraulic on-off switch etc..
3.The machine is equipped with a frequency converter drive motor, a hydraulic station motor, two solenoid directional valves for tile pressing, and two hydraulic solenoid valves for cutter.
4.PLC with 14 input /10 relay output, just to meet the input and output requirements. With KDN text screen, you can complete the parameter settings, alarm display, production data display, etc..

DSG-01 / DSG-02 yuken solenoid valve

1/8 solenoid operated directional Yuken DSG-01 hydraulic valves, the power is 6 W,about 1/5 of Yuken DSG-01 series (29 W),and can reduce a lot of running costs.Maximum operating pressure is 32 MPa and maximum flow is 63 L/min, identical to Yuken DSG-01 series yuken type hydraulic valves,the valves can provide high pressure and high flow with low pressure drop,features can be materialized by taking use of powerful wet solenoid and rational flow channel.

Max.Operating Pressure: approx.10% increased 31.5^35 MPa.
Max. T-Line Back Pressure: approx. 30% increased 16^21 MPa.
Max.Flow Rate:approx.60% increased 63.4~100L/min.
Low Pressure Drop: Pressure drop of these valves can be reduced by 10 % from 1.0 to 0.9 MPa (145 to 131 PSI), by comparing to existing lines*; the valves can effectively reduce energy consumption .

{* At Flow Rate: 60 L/min (15.9 U.S.GPM), Spool Type: 3C2)

With characteristics compact and light weight, even with high pressure, high flow and low pressure drop, these valve bodies with DC double solenoids are compact and weight is light; overall length and weight can be reduced from 210 to 205 mm (8.26 to 8.07 inch) and from 2.2 to 1.94 kg,respectively.

In addition to the standard valves,shockless type are available in high pressure and high flow, and can eliminating noise and vibration in piping when spool changeover is available.

Due to the powerful magnetic and spring force of the solenoids,shockless type can operate stable,and these valves are antipollution,especially in stable operation.

IP65-is equivalent to high dust-proof and water-proof.
With characteristics of dust-proof and water-proof.
Products can be used on various situation and had passed CE standard.
In addition highly reputable solenoid operated directional yuken standard hydraulic valve series,we had put production of “energy-saving solenoid operated directional Yuken valve DSG-01” with high pressure and flow,which can reduce holding power.

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The connection of hydraulic valve

There are five ways to connect the hydraulic valve.

1.Threaded Connection

The valve on the valve port of the valve body is called a tube valve. The oil outlet of the tube valve is connected with a threaded pipe joint, and is fixed on the pipeline. This connection is suitable for small flow simple hydraulic system. The utility model has the advantages of simple connection mode and convenient layout. The disadvantages are that the components are scattered, the space is large, the pipeline is staggered, and the joints are various, which is not convenient for loading and unloading.

2.Flange Connection

It is connected with a flange at the end part of the pipe body through a screw hole on the valve body (usually 4 screw holes). This type of valve is called flanged connection valve. Suitable for large flow hydraulic system with a diameter of 32mm or more.The advantages and disadvantages is same to thread connection.

3.Plate Connection

Each valve port of the valve is arranged on the same installation plane, and the connection is provided with a screw hole, this valve is called plate type valve, such as an solenoid reversing valve. Fix the plate type valve on the flat plate or valve block type connection body which has corresponding oil outlet with screw. This connection has the advantages of convenient replacement of components, no influence of pipelines, and possibility of centralized arrangement of valves. The connecting body connected with the plate type valve is provided with two forms of a connecting plate and an integrated block.

4.Stack Connection

The bottom surface of the various hydraulic solenoid valves are done as the bottom of the plate valve, in the connection surface of the various hydraulic valves of same specifications,the position of the oil port, the position of the screw hole and the connection size are all the same (according to the connection size of the same specification of the reversing valve), this valve is called stack valve. According to the requirements of the system, the same specifications and the various functions of the stack valve to stack up in a certain order, can form a stack valve type hydraulic device. The bottom of the stack valve type hydraulic device is generally the bottom block, and the bottom block is provided with an oil inlet P, oil return port T and an oil port A, B and a pressure gauge oil port which are connected with the actuating element. A stack valve group generally controls an execution element. If there are several executive components in the system need to be centrally controlled, several vertical stacking valve group can be arranged side by side on the multi floor. Inter element connections of the hydraulic system with stack valve do not use the tube, either use other forms of connectors, which has the advantages of compact structure, small volume, low pressure loss and leakage loss of the system, especially the change of hydraulic system is more convenient and flexible. The stack valve is a standardized component, can be assembled only by drawing the schematic diagram of the stack valve hydraulic system, so the design workload is small, widely used.

5.Cartridge Connection

The valve is made into a cylindrical element (which valve body is removed) – cartridge valve. The cartridge solenoid valve is directly inserted into the socket hole of the valve block with holes, constituting the hydraulic system. Its structure is very compact. All kinds of pressure valve, flow valve, directional valve, proportional valve can be made into the cartridge valve.

DG4V5 vickers solenoid valve

Max. pressure 315 bar (4500 psi)
Max. flow rates Up to 120 L/min(32 USgpm),
dependent on spool
Mounting surface ISO 4401 size 05
NFPA D02
DIN 24340 (NG10)

Four-port solenoid operated directional control Vickers DG4V5 valves with four-land spool design,so as to to facilitate of smooth, and response to variable speeds.

The range including:

AC and DC wet-armature solenoid options with ISO 4400 (DIN 43650) electrical connections and manual overrides.
Variable speed changeover potential in all DC models;

More spool types:with spring-offset, spring-centered and detented arrangements.

DG4V5 vickers hydraulic solenoid valve is compatible to fluid :

AC or DC-voltage models is suitable for petroleum oils, water-in-oil (invert) emulsions or phosphate esters. AC-voltage models can be used on water glycols.

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Working principle of hydraulic grapple

Hydraulic grapple is one of the common types of grapples, which is widely used in the fields of loading and unloading stone, waste steel and log. Hydraulic grapple use the excavator hydraulic pump as the power source, divided into the transmission power and power two parts, one is to rotation, the other is to grab or loose. The rotation of the grapple is accomplished by a durable, large torque motor. The oil cylinder of the grapple is divided into single cylinder and double cylinder, through the expansion of the oil cylinder to grab and release, different types of oil cylinder with different performance of grab.

Hydraulic grapple is often divided into rotary and non rotary:
1.The grapple without hydraulic rotation is connected with the oil channel of the excavator bucket cylinder, do not need to install the hydraulic pipeline and electric hydraulic control valve, quick installation, easy to use.
2.The grapple with the rotation needs to add a set of electric hydraulic control valve and pipeline to control; Hydraulic grapple with hydraulic cylinders are equipped with protective devices.

BSTIND DG4V-3-60 vickers directional valve

Flows is 80 l/min (21 USgpm), 6* Design
P, A & B Pressures is 350 bar (5000 psi), T Pressures is 210 bar (3000 psi)

Functions of DG4V3 vickers hydraulic valves are as following:
With spring return= without any sign
Without spring return =O
Without spring return with detent =OF
High-performance wet-pin solenoid with detachable coil

Coil rating
Full power coils
A – 110V AC 50Hz
Bo – 110V AC 50Hz/120V AC 60 Hz
C – 220V AC 50 Hz
Do – 220V AC 50 Hz/240V AC 60 Hz
G – 12V DC
H – 24V DC
Low power coils,
(Not available with “N” – No-spring detented models)
BL – 110V 50 Hz/120V 60 Hz
DL – 220V AC 50 Hz/240V AC 60 Hz
GL – 12V DC
HL – 24V DC

Analysis of downstream application of hydraulic system

Hydraulic transmission is to use liquid as working medium to transmit energy and control the transmission mode. The hydraulic transmission technology has the advantages of large power to weight ratio, small volume, high frequency response, high pressure and good flow control, flexible transmission of power, easy to achieve linear motion, stepless speed regulation, etc..

The complete hydraulic system is composed of five parts: power unit, actuator, control and adjustment device, auxiliary equipment and working medium. Hydraulic components are composed of hydraulic pumps, hydraulic cylinders, hydraulic motors, hydraulic directional valves, supercharger and other hydraulic system components.

In the hydraulic system, hydraulic pumps and motors, hydraulic system valves and cylinders are the most valuable parts, accounting for 72% of the total value of the hydraulic system.

Because of the advantages of hydraulic transmission technology, it is widely used in downstream. All application areas such as engineering machinery, agricultural machinery, machine tools, machinery, metallurgy, mining machinery, forging port equipment, airport equipment, ships, oil and gas production, industrial robots, automated production line etc..

BSTIND 4WE10 rexroth hydraulic solenoid valve

Standard flow of 4WE10 bosch rexroth hydraulic Valves is 120l/m,and working pressure of hydraulic direction valve is 32Mpa,the same as NG5 valve and Cetop5 valve.4we10 rexroth type directional valve usually used on hydraulic power,hydraulic work system and industrial hydraulic equipment.

4/3, 4/2 directional valve with wet-pin DC or AC voltage solenoids
Size 4WE10 has Hydraulic Solenoid Valve
Component series has 3X (30~39),4X (40~49)
The maximum operating pressure is 315 bar
The maximum flow is 120 l/min

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What are the installation of hydraulic valve

According to the function of hydraulic valves can be divided into three categories, the flow control valve (including throttle valve, control valve, diversion valve), hydraulics directional control valve (including one-way valve and valve), pressure control valve (including overflow valve, relief valve, sequence valve, relief valve, pressure relay).

According to the operation mode, the hydraulic valve can be divided into manual, pedal, motor, electric, spring control, hydraulic, electro-hydraulic, hydraulic pilot control, etc..

Hydraulic valve installation
The installation of hydraulic valves are mainly divided into 5 types, which is, pipe type, plate type, plate type, stack type, cartridge type, flange type. The inlet and outlet ports of the pipe valves are provided with internal threads, which are connected with pipelines and other components through a connected pipe joint. Chip valve also known as multiway valve, is developed from the pipe type manual reversing valve: a control panel with a spool valve to control a set of actuators – hydraulic cylinder or hydraulic motor. The oil port connecting plate valve is not directly on the valve, but on the baseplate, the valve is fixed on the baseplate by bolts. The stack valve is the extension, expansion and integration of the plate valve. The cartridge valve can be seen as a valve that does not wear a coat because they do not have a housing and must be installed in a valve block or manifold.

BSTIND is a professional manufacturer of solenoid directional valve,high quality and Chinese factory price for B2B customers.Quick delivery,bulk purchasing,reply in 24H.

DG4V5 Vickers hydraulic solenoid valve

Max. pressure 315 bar (4500 psi)
Max. flow rates Up to 120 L/min(32 USgpm),
dependent on spool
Mounting surface ISO 4401 size 05
NFPA D02
DIN 24340 (NG10)

Four-port solenoid operated directional control Vickers DG4V5 valves with four-land spool design,so as to to facilitate of smooth, and response to variable speeds.

The range including:

AC and DC wet-armature solenoid options with ISO 4400 (DIN 43650) electrical connections and manual overrides.
Variable speed changeover potential in all DC models;

More spool types:with spring-offset, spring-centered and detented arrangements.

DG4V5 vickers hydraulic solenoid valve is compatible to fluid :

AC or DC-voltage models is suitable for petroleum oils, water-in-oil (invert) emulsions or phosphate esters. AC-voltage models can be used on water glycols.

REXROTH introduced the LC2A-1X series hydraulic valve

According to the German local time July 2nd reported: Rexroth LC2A-1X series valve has ISO7368 certification, users can directly mount any LFA logic coverage in Rexroth standard procedures to create hydraulic functions required. This method increases the flexibility for future modifications, since only logical coverage needs to be replaced to meet the new requirements.

Rexroth is committed to providing safe, accurate, efficient and cost-effective transmission and control technologies for all types of machinery and systems. The company integrates the global application experience, research and develop innovative products, provides solutions and services for customers of mechanical applications and engineering, factory automation and renewable energy in each market segment. Rexroth also provides customers with a variety of hydraulic, electronic transmission and control, pneumatic, gear, linear transmission and assembly technology. The company operates in more than and 80 countries, with more than 37,500 professional employees, global sales of nearly 6 billion 500 million euros in 2012.

BSTIND can produce most types of REXROTH hydraulic valves, especially 4WE6 and 4WE10 series hydraulic solenoid valves

4WE6 hydraulic solenoid valves

4WE10 hydraulic solenoid valves

Three disadvantages of hydraulic system

1.Heating

Because the medium (hydraulic oil) exist different velocity in different parts of the flow process, leading to the existence of the internal friction, there is also a friction between the liquid and the inner wall of the pipeline at the same time, these are the causes of the hydraulic oil temperature rise. The increase of temperature will lead to the increase of internal and external leakage and reduce the mechanical efficiency. At the same time, due to the high temperature, hydraulic oil will expand, resulting in compressibility increase, so that the control action can not be transfered very good.
Solution: heating is an inherent feature of the hydraulic system, can not be eradicated as far as possible to alleviate. The use of good quality hydraulic oil, hydraulic piping layout should try to avoid the elbow, the use of high quality pipes and pipe joints, hydraulic flow valves, etc..

2.Vibration

The vibration of the hydraulic system is one of the chronic illness. Because of the high speed flow of the hydraulic oil in the pipeline and the impact of the hydraulic pressure control valve opening and closing process is the cause of the vibration of the system. Strong vibration will cause the error of the control action of the system, will also cause error of some the more precise instrument of the system, resulting in system failure.
Solution: the hydraulic pipe should be fixed to avoid sharp bends. Avoid change the direction of fluid flow frequently, the vibration mitigation measures should be done when can not be avoided. The entire hydraulic system should have good damping measures, while avoiding the external forces on the system.

3.Leakage

The leakage of hydraulic system is divided into internal leakage and external leakage. Internal leakage refers to the leakage process occurs in the system, such as the leakage of hydraulic cylinder piston on both sides, the leakage between control valve spool and hydraulic directional spool valve. Although the internal leakage will not cause the loss of hydraulic oil, but due to the leakage, the established control action may be affected until the system failure. External leakage is the leakage between the system and the external environment. Hydraulic oil leaking into the environment directly, in addition will affect the working environment of the system, but also lead to system failure caused by insufficient pressure. Leakage of oil into the environment will also gain the risk of fire.
Solution: the use of good quality seals, improve equipment processing accuracy.

BSTIND Z2FS modular throttle check valve

MAX 315 bar, MAX 160 L/min, MAX 35MPa

Sandwich plate valve
Porting pattern to ISO 4401-05-04-0-05, NFPA T3.5.1 R2 and ANSI B93-7 D05
For limiting the main or pilot oil flow of 2 actuator ports
3 adjustment elements:
-Lockable rotary knob with scale
-Spindle with hexagon socket and scale
-Rotary knob with scale
For meter-in and meter-out throttling

Hydraulic components can be divided into power components and control components and executive component

Hydraulic components can be divided into power components and control components and executive component. Although they are all hydraulic components, their own function and installation of the technical requirements are not the same.

Power components: refers to a variety of hydraulic pumps, gear pumps, vane pumps, piston pumps, screw pumps.
1.Gear pump and series pump (including external and internal meshing) structural types.
2.Vane pump (including single stage pump, variable pump, double stage pump, double pump).
3.The plunger pump is divided into axial piston pump and radial piston pump, axial piston pump is divided into variable pump, quantitative pump (variable pump is divided into manual and variable pressure compensating variable, servo variable etc.) . From the structure is divided into the end face type and oil distribution valve type oil distribution mode, and the radial plunger pump with oil type, basically for valve type oil distribution.

Executive component: hydraulic cylinder and hydraulic motor, hydraulic cylinder hydraulic cylinder piston, piston hydraulic cylinder, hydraulic cylinder, hydraulic cylinder combination swing hydraulic motor; gear hydraulic motor is divided into hydraulic vane motor, piston hydraulic motor.

Control components: reversing valve, modular check valve, hydraulics directional control valve.
Pressure control valve: relief valve, pressure relief valve, sequence valve, hydraulic pressure valve, etc.
Flow control valve: throttle valve, speed control valve, shunt valve.

Auxiliary components: in addition to the above three parts components, including pressure gauge, oil filter, accumulator, cooler, fittings {mainly include: various pipe fittings (flared, welding type, sleeve type, SAE flange), high pressure ball valves, quick couplings, hose assembly, pressure measuring joint and the pipe clip} and tank, they are also very important.

4WE3-61 hydraulic solenoid miniature hydraulic valve

Max working oil pressure P.A.B : 31.5 MPa
Max oil pressure for T chamber : 10 MPa
Rated flow : 10 l/min
Max flow : 15 l/min

NG3 valve with 3 holes
4/2-way impulse valve
4/3-way with centered mid position spring
4/2-way with spring reset.
Q max.=15l/min,P max.=315Bar

The advantages of hydraulic system

Compared with mechanical transmission and electric drive, hydraulic transmission has the following advantages:
1.Various components of hydraulic transmission can be layout conveniently and flexibly .
2.Light weight, small size, small inertia, fast reaction speed.
3.Easy operation and control, can achieve a wide range of stepless speed regulation (speed range of 2000:1).
4.Automatic overload protection.
5.Generally use mineral oil as working medium, relative motion surface can be self lubrication, long service life.
6.Easy to achieve linear motion.
7.It is easy to realize the automation of the machine. When using the combined control of the electro-hydraulic, not only can achieve a higher degree of automatic control process, but also can achieve remote control.

BSTIND is a professional manufacturer of hydraulic system valves,high quality and reasonable price,serve for B2B customers,looking forward to get your inquiry.

The hydraulic system is divided into different forms

The hydraulic components and gradually realize the standardization and serialization of the varieties, its specifications, quality and performance have been greatly improved, especially the new technology such as electronic technology, servo technology and so on, the quality of the hydraulic system has been greatly improved, which has played an important role in the national economy and military industry. From different points of view, the hydraulic system can be divided into different forms.

1.According to the circulation of oil, hydraulic system can be divided into open system and closed system. Open system refers to the hydraulic pump drain oil from the tank, the oil through a variety of electric hydraulic control valves, to drive hydraulic components, then return to the tank through the hydraulics directional control valve. The structure of the system is relatively simple, and can play the role of heat dissipation and precipitation of the fuel tank, but because the oil is often in contact with the air, the air is easy to penetrate into the system, resulting in the unstable motion of the mechanism. The oil tank of open system is big, and the oil pump self-priming performance is good. In the closed system, the oil inlet pipe of the hydraulic pump is directly connected with the oil return pipe of the actuating element, the working fluid in the system for closed loop pipeline.Its structure is compact, less contact with air, and air is not easy to penetrate the system, so the transmission is more stable. The speed and direction of the working mechanism are realized by adjusting the variable mechanism of the pump or the motor, so as to avoid the hydraulic shock and energy loss in the process of the opening system. However, the closed system is more complex than the open system, because there is no oil tank, the oil cooling and filtration conditions are poor. In order to compensate for the leakage in the system, a small flow oil pump and oil tank is needed. As the single pole double acting cylinder large cavity flow range, in the work process will make use of power down, so the implementation of a closed system components for hydraulic motor.

2.According to the number of hydraulic pumps in the system, can be divided into single pump system, double pump system and multi pump system.

3.According to the different forms of hydraulic pump, can be divided into quantitative pump system and variable pump system. The advantages of variable pump is that it can make full use of the power of the engine within the scope of the regulation, but its structure and manufacturing process is complex and high cost, which can be divided into manual variables, as far as possible control variables, servo variable, pressure compensating variable and constant pressure variable, hydraulic variable etc..

4.According to the different ways of oil supply, the system can be divided into series system and parallel system. In the series system, the oil return of the last executive element which is the oil inlet of the next executive element, and the pressure of each component is reduced by one time. In the series system, when the main pump supply oil to each of the actuators controlled by the multi way valve, as long as the outlet pressure of the hydraulic pump is sufficient, the movement of the actuating elements can be realized. However, due to the pressure of the components are superimposed, so the external load capacity will be reduced with the increase of the number of components. In parallel systems, when a hydraulic pump supply oil to a set of actuators, the flow into each of the actuators is only part of the output flow of the hydraulic pump. Flow distribution varies with the load of different parts, first into the small load actuator, the simultaneous action can be achieved only when the load of the actuators are equal. The advantages and disadvantages of the mechanical performance of the full hydraulic transmission mainly depends on the performance of the hydraulic system, including the quality of the components, the basic circuit is appropriate or not, etc.. The performance of the system, in addition to meet the functional requirements, should be evalutated in installation and debugging efficiency, power from hydraulic system use, speed range and fine tuning characteristics, vibration and noise and the system is convenient and reliable etc.. Modern engineering machinery almost all use the hydraulic system, and combine with the electronic system and computer control technology, become an important part of modern construction machinery.

Disadvantages of hydraulic system

1.Because of the large resistance and leakage of fluid flow, the efficiency is low. If not handled properly, the leakage not only pollute the site, but also may cause fire and explosion accidents.
2.Because the performance of the work is easy to be affected by the temperature change, it is not suitable to work at high or low temperature.
3.High accuracy of hydraulic components, such as the hydraulic pressure valve, so the price is relatively expensive.
4.Due to the leakage of the liquid medium and the compressibility, it can not get the strict transmission ratio.
5.Hydraulic transmission is not easy to find out the reasons for failure; require a higher level of technology for operation and maintenance.

Requirements and processing of hydraulic parts surface

As the main parts of the oil cylinder, the single pillar, the hydraulic frame and so on, the processing quality of cylinder directly affects the use life and reliability of the whole product. The requirement of cylinder processing is high, the inner surface roughness requirement of Ra0.4 ~ 0.8, the degree of coaxiality, wear resistance requirements is strict. The basic feature of the cylinder is the deep hole processing, the processing personnel has been plagued by its processing.

Applying rolling processing, because of the residual compressive stress in the surface layer, it is helpful to the sealing of small cracks on the surface and stop the extension of erosion. Therefore, the corrosion resistance of the surface can be improved, and the fatigue crack can be prolonged or enlarged, thereby improving the fatigue strength of the cylinder. Through rolling processing, rolling the surface to form a layer of cold hardening layer, reduces the elastic and plastic deformation of the grinding contact surface, thus improving the wear resistance of the inner wall of the cylinder, while avoiding burns caused by grinding. After rolling, the surface roughness value decreases, which can improve the matching properties.

The hydraulic operated valve as the control center of the hydraulic system, move frequently, the requirements of the device precision, sealing and reliability of each part are very high, most of the enterprises are used to improve the precision with rolling processing.

The harm of hydraulic impact and the measures to reduce hydraulic impact

The harm of hydraulic impact

1.The huge the instantaneous pressure causes the hydraulic components, especially the hydraulic seals, to be destroyed.
2.The system produces strong vibration and noise, and the oil temperature rise.
3.The pressure control components (such as pressure relays, hydraulic sequence valves, etc.) to produce a false action, resulting in equipment failure and accidents.

Measures to reduce hydraulic impact

1.Extension of valve closing and moving parts reverse braking time
When the valve is closed and the reverse braking time of the moving part is more than 0.3s, the hydraulic impact is greatly reduced. Hydraulic directional valves with adjustable commutation time can be used to control hydraulic impact. Such as the use of damping solenoid operated relief valve can be adjusted by damping and slow down the speed of the main valve spool through controlling the pilot valve pressure and flow, hydraulic valve is similar.
2.Limiting the flow rate of the liquid in the pipe and the speed of the moving parts
Machine tool hydraulic system, often limit the liquid flow rate in the pipeline to 5.0m/s, the speed of moving parts is generally less than 10m/min.
3.Increase the pipe diameter or the use of rubber hose
It can reduce the propagation velocity of the pressure shock wave in the pipeline, at the same time, increase the inner diameter of the pipeline can also reduce the flow rate of the liquid.
4.Arranged accumulator near the hydraulic impact source
The pressure shock wave reciprocating time is shorter than the valve closing time, and reduce the hydraulic impact.

What is hydraulic

It is a term of hydraulic machinery industry, electromechanical industry .Hydraulic power can be used as a hydraulic transmission. Hydraulic pressure can also be used as a control method, called hydraulic control.

Hydraulic transmission use liquid as the working medium, use liquid pressure energy to transfer power.

Hydraulic control is the control signal transmission mode using pressure liquid. Hydraulic control usually includes hydraulic open loop control and hydraulic closed loop control. Hydraulic closed-loop control is also called hydraulic servo control, usually including the electric hydraulic servo system and mechanical hydraulic servo system etc..

A complete hydraulic system consists of five parts, namely an energy device, an executive device, a control adjustment device (hydraulic valve), an auxiliary device and liquid medium. The hydraulic pressure is widely used in industry and civil industry because of its large transmission power, easy to transfer and configuration. The executive component of hydraulic system (hydraulic cylinder and hydraulic motor) is to convert the pressure energy into mechanical energy. The energy source of hydraulic system (hydraulic pump) is to convert the mechanical energy of the prime mover to the pressure energy of the liquid.

BSTIND is professional in designing and manufacturing,sales of electric hydraulic control valve. Factory With more than 20000 square meters workshops.And there are about 300 workers and 50 among which are senior or intermediate technical engineers. BSTIND had passed ISO9001:2008 and CE certificates.Annual production is selling about 0.6 millions hydraulic valves.

what-is-cavitation/

In the hydraulic system, the air in the oil will be separated and a large number of bubbles will be formed if the pressure is lower than the air pressure at the working temperature of the oil; when the pressure is further reduced to the saturated vapor pressure at the working temperature of the oil, the oil will rapidly vaporize and produce a large number of bubbles. These bubbles are mixed in the oil, resulting in cavitation, so that the oil filled in pipes or hydraulic components turn into a discontinuous state, this phenomenon is generally known as the cavitation phenomenon.

Cavitation occurs at the inlet and outlet of the hydraulic pump. When the oil flows through the narrow channel of the manual hydraulic valve port, the liquid flow rate increases, the pressure drops sharply, and the cavitation phenomenon appears. Hydraulic pump installation height is too high, oil suction pipe diameter is too small, oil absorption resistance is too large, or hydraulic pump speed is too high, inadequate oil absorption, etc., are likely to cause cavitation.

Cavitation occurs in hydraulic system, the bubble with the oil flow to the high pressure area, under high pressure air bubbles will quickly break down, the liquid around to fill this hole at high speed, the liquid in the high-speed collision and form local hydraulic impact, the local temperature and pressure increased sharply, caused a strong vibration and noise.

Pipe wall and element surface near bubble condensation, due to the long-term impact of hydraulic shock and high temperature, as well as the strong corrosion of the gas in the oil, so that the metal element and particles of the wall surface are spalling, the corrosion on the surface of the cavitation phenomenon called gas etching.

In order to prevent cavitation and gas etching, the following measures can be taken:
1.Reduce the flow of small holes and gaps in the pressure drop, the general hope that the pressure ratio before and after the gap is p1/p2<3.5.
2.To correctly determine the diameter of hydraulic pump suction pipe in the pipe, limit the flow of liquid, reduce the suction height of hydraulic pump, reduce the pressure loss in the pipe joint oil pipeline, a good seal, the auxiliary pump for high-pressure cartridge hand pump.
3.The entire pipeline system should be as straight as possible, avoid sharp bends and local narrow.
4.Improve gas etching resistance of components.

The causes of hydraulic impact

1.Hydraulic shock caused by sudden closing of valve
When the hydraulic valve is opened, the liquid flow in the pipe. When the valve is suddenly closed, start the rapid conversion of the kinetic energy of liquid into pressure energy from the valve, resulting in a high pressure shock wave from the valve to the chamber; since then, the cavity began to convert the pressure of liquid into kinetic energy, liquid reverse flow; then, the liquid kinetic energy is transformed into pressure energy and a high pressure shock wave is formed, so the energy conversion is repeated, and the pressure oscillation is formed in the pipeline. Because of the influence of the internal friction and the elastic deformation of the pipe, the oscillation process will gradually decline and become stable.

2.Hydraulic impact caused by sudden braking or reversing of moving parts
The hydraulics directional control valve closes the oil return passage of the hydraulic cylinder and the moving part is braked, the kinetic energy of the moving part in the moment can be transformed into the pressure energy to closed the oil, and the pressure is increased rapidly, forming the hydraulic impact.

3.Hydraulic shock caused by malfunction or insensitivity of some hydraulic components
When the hydraulic system relief valve in the system to do the use of safety valve, if the system overload while the safety valve can not be opened in time or simply can not open, it will lead to a sharp increase of the pressure of the pipeline system, lead to hydraulic impact.

The principle of the hydraulic system

It consists of two cylinders （click here to learn more about BSTIND hydraulic cylinder check valve） of different sizes, filled with water or oil in the liquid cylinder. Filled with water called “water press”; oil filled with the “oil press”. Each cylinders with a sliding piston, if add a certain value pressure on the small piston , according to Pascal’s law, the small piston pass the pressure through the liquid to the large piston, lift the large piston up. Set the cross-sectional area of the small piston is S1, the downward pressure on the small piston is F1. Thus, the small piston pressure on the liquid is P=F1/SI, the size of the liquid can be transferred to all directions. The pressure on the piston is also equal to P. If the cross-sectional area of the large piston is S2, the pressure P on the piston is generated by the upward pressure F2=PxS2, cross-sectional area is multiples small piston cross-sectional area. From the type known to add in a small piston of a smaller force, the piston will be in great force for which the hydraulic machine used to suppress plywood oil extract heavy objects such as forging steel.

The principle of hydraulic pressure in a certain mechanical and electronic systems, relying on the hydrostatic pressure of the liquid medium, the completion of the backlog of energy, transmission, amplification, to achieve the lightweight, scientific, maximize of the mechanical function.

By using hydraulic principle, the hydraulic transmission system can be constructed.

BSTIND is professional in designing and manufacturing,sales of Hydraulic System Valve. Factory With more than 20000 square meters workshops.And there are about 300 workers and 50 among which are senior or intermediate technical engineers. BSTIND had passed ISO9001:2008 and CE certificates.Annual production is selling about 0.6 millions hydraulic valves.

The components of hydraulic system

A complete hydraulic system consists of five parts, which are power components, executive components, control components, auxiliary components and working media.

The function of a power element is to convert the mechanical energy of the machine to the pressure energy of the liquid. A power element is a hydraulic pump in a hydraulic system that supplies power to the entire hydraulic system. The structure of the hydraulic pump generally divide into gear pump, vane pump, piston pump, screw pump.

The function of the executive element is to convert the pressure energy of the liquid into the mechanical energy, and to drive the load for a linear reciprocating or rotary motion. Executive element has a hydraulic cylinder and a hydraulic motor.

Control components (which is a variety of hydraulic valves) in the hydraulic system to control and regulate the pressure, flow and direction of the liquid. According to the different control functions, hydraulic valves can be divided into hydraulic pressure control valves, hydraulic flow control valves and hydraulic directional control valves. Pressure control valve is divided into relief valve, pressure relief valve, sequence valve, etc.; flow control valves including throttle valve, regulating valve, diversion valve; directional control valve includes one-way valve, shuttle valve, reversing valve, etc.. According to different control methods, hydraulic valves can be divided into switch control valve, fixed value control valve and proportional control valve.

Auxiliary components including accumulators, filters, cooler, heater, tubing, pipe fittings, oil tank, pressure gauge, flow meter, sealing device, effect of their connection, oil filter and oil pressure measurement.

Working medium refers to various types of hydraulic transmission of hydraulic oil or emulsion, there are a variety of mineral oil, emulsion and synthetic hydraulic oil. The hydraulic system is to realize the movement and power transmission.

Reasons for the leakage of the hydraulic solenoid operated directional valves

Adjustable hydraulic pressure relief valves more or less have the problem of internal leakage, this is related to the structure and working principle of the solenoid operated directional valves, a certain range of internal leakage is normal, can not be completely avoided. The working principle of the pressure operated relief valve is that electromagnetic power push rod to make the relative movement of the spool after the electric drive, so as to open or close the corresponding oil hole. In order to ensure the smooth movement of the valve core in the valve body, need to maintain a certain gap between the two, otherwise the adjustable hydraulic pressure relief valve and the valve body will keep in close contact and  not be able to move under the influence of friction.

The gap size of the adjustable hydraulic pressure relief valve body and the valve core is known as the matching precision. It need to be strictly controlled in order to ensure the stability of the 50 psi pressure relief valve. The internal leakage of the hydraulic system directly affects the working efficiency of the hydraulic system, and can easily lead to malfunction of the system.

But need to point out that the matching precision of the pressure operated relief valve is not simply the pursuit of precision, but should select the most appropriate solution based on the requirements of the work conditions and cost.As we all know, the hydraulic system in the hydraulic oil is very easy to mix with small impurities and it is difficult to completely eliminate. It is usually used to filter the impurities in the fuel tank with a single filter. This method is relatively simple, but the accuracy of the low cost filter is limited, can not effectively filter small impurities. If the matching precision of the hydraulic solenoid valve above the filter precision, valve core is easy to be blocked by the impurities not filtered , resulting in the solenoid valve failure. For high precision solenoid operated directional valve, it is generally recommended to adopt high precision filtration equipment, such as cotton core, which will increase the cost of the whole system. Therefore, the requirements for the electromagnetic solenoid operated directional valves leakage should be based on the actual work situation.

Some low price 50 psi pressure relief valves can increase the internal leakage after a certain period of time, may be due to the valve body using of low hardness material, the gradual wear and tear in the work lead to poor accuracy.

If pressure operated relief valves connection surface oil leakage, generally should check the installation of adjustable hydraulic pressure relief valve and the bottom plate is flat or not, the torque and the material of connecting bolts should be consistent. The problem that is often overlooked is that the hardness of the O type ring is mounted. The lower hardness of the sealing ring should not be used for the sealing of the high-pressure system, can be replaced if necessary.

Fault solution for leakage of electromagnetic 3 position 4 way directional control valve

Modular controls solenoid valve due to the material, processing accuracy, the use of wear and other reasons, there may be an abnormal increase in internal and external leakage, resulting in a decrease in pressure, or through the flow problem and other issues.

The leakage of electromagnetic modular controls solenoid valve leakage is increased, the most common problem for the O type sealing ring. Should check whether the O ring is installed in place, if there is a squeeze, damage and other issues, it is best to replace the sealing ring.

Also need to check the size of the sealing ring, and whether it is consistent with the size of the sealing surface, O type of ring is too large or too small will affect the sealing effect.

Secondly, O type ring material hardness in high pressure situation will also affect the stability of the seal, the lower hardness of the O ring is not suitable for solenoid operated relief valve seal, should choose high hardness O type ring to get better sealing effect.

The internal leakage of the electromagnetic 3 position 4 way directional control valve is increased, which causes the system pressure to reduce, the flow loss, and the work efficiency of the hydraulic system. Common cause of this failure is solenoid operated pressure relief valve body hole and spool wear in the long-term movement of the process of friction,lead to excessive solenoid operated relief valve clearance, causing leakage. Can repair the outer diameter of the spool, or replace the valve core.The material hardness of valve core and valve body directly determines its service life.