Solenoid valve is an automatic basic element used to control the direction of fluid, belonging to actuator; It is usually used in mechanical control and industry
Above the valve, the medium direction is controlled, so as to control the valve switch.

Solenoid valves are divided into three categories in principle:

1)    direct acting solenoid valve:

Principle: when energized, the solenoid coil generates electromagnetic force to lift the closing part from the valve seat and open the valve; when powered off, the electromagnetic force disappears, the spring presses the closing part on the valve seat and the valve closes.

 

Features: it can work normally under vacuum, negative pressure and zero pressure, but the diameter generally does not exceed 25mm.

 

2)    distribution solenoid valve Direct acting solenoid valve:

Principle: it is a combination of direct acting and pilot type. When there is no pressure difference between the inlet and outlet, the solenoid force will directly lift the small pilot valve and the closing parts of the main valve upward and open the valve. When the inlet and outlet reach the starting pressure difference, the solenoid force will pilot the small valve, the pressure in the lower chamber of the main valve will rise and the pressure in the upper chamber will fall, so as to facilitate the opening of the valve Push the main valve upward with differential pressure; when power is off, the pilot valve uses spring force or medium pressure to push the closing part and move downward to close the valve.

 

Features: it can also act when there is zero differential pressure or vacuum and high pressure, but the power is large, so it must be installed horizontally.

 

3)    pilot solenoid valve:

Principle: when power is on, the solenoid force opens the pilot hole and the pressure in the upper chamber drops rapidly, The pressure difference between the lower part and the higher part is formed around the closing part, the fluid pressure pushes the closing part to move upward, and the valve opens; in case of power failure, the spring force closes the pilot hole, the inlet pressure quickly forms the pressure difference between the lower part and the upper part around the valve closing part through the bypass hole, and the fluid pressure pushes the closing part to move downward to close the valve.

 

Features: the upper limit of the fluid pressure range is high, which can be installed arbitrarily (to be customized) but the fluid differential pressure condition must be met.

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Post time:        Sep-25-2021

Compressed Air Supply

Adequate sizing of compressors and feed lines is the first place to start to ensure proper system operation. Consistent plant air pressure with suitable flow allows pneumatic devices to operate as designed, as low or varying air pressure can negatively impact the final product and overall machine sequence. For example, a manufacturing plant was experiencing low air pressure in its facility at the end of the day shift, causing one of the machines to fault due to low air pressure in its pneumatic actuation system. The problem was found to be high-volume air consumers nearby, namely blow guns being used to clean machines at the end of each day. Insufficient capacity at the air compressor, or undersized plant air supply tubing and piping is a common issue and one to look out for. If air consumption is a major concern for your factory, check out our Interactive Air Consumption Calculator here.

Air Flow Control

Once consistent and correct pneumatic system air pressure and flow is established, plant supply air should be connected to a manual, lockable air dump valve at each use point. This lockout, tag-out capability is important for isolating a machine—or a module of a large machine—for changeover, maintenance or tooling changes. A filter regulator should also be installed at the air dump valve. The filter removes dust particles and water that can cause wear and operation problems for pneumatic system components. A regulator is required to throttle to the design air pressure at the use point, typically 60 to 90 psi, as the plant air supply is usually higher, about 100 to 130 psi. Operating at the design pressure as opposed to plant pressure will reduce wear on pneumatic components.

An electric soft start valve downstream of the regulator allows air pressure to gradually increase at start-up, preventing sudden banging or slamming of cylinders at power up. This is especially important if 4-way, 2-position valves are used because a 2-position valve spool maintains its position after power off and the removal of air. When power and air is reapplied, air will return to the cylinder. If all air was exhausted, no air is available on the other side of the cylinder. This makes speed control with flow controls non-functional. The uncontrolled speed of the cylinder could cause a high-speed stroke, commonly ending with a bang. When soft start valves are correctly applied, a machine will typically return to its home position slowly and smoothly at power up.

Lubricators should be used sparingly and only when necessary. Most modern pneumatic components come lubricated from the factory and do not need oil. However, pneumatic motors on air tools and other equipment do require a lubricator and one should be supplied in these instances.

Cylinder Types

Pneumatic cylinders are a popular way to clamp, position and transfer parts in automated equipment and although there are many types of cylinders, their construction is fairly similar from one to another. Take a moment and review the Pneumatic Cylinders article to get a basic understanding of what cylinders are and how they operate. Understanding the basics helps to know how different applications affect the cylinder and piston rod.

Cylinder Sizing

The load is the primary consideration when determining cylinder type and piston size. The piston area (force factor) multiplied by the air pressure in the cylinder gives the available force. A general rule is to select a force factor that will produce a force 25% greater than the load to help compensate for friction and losses. Pneumatic systems are quite forgiving in terms of oversizing, but using components that are too big adds unnecessary expenses in terms of both purchase price and energy consumption.

The bore size (force factor) determines force at a given pressure. The operating pressure, which in a plant can typically range from 10 to 150 psi, is the first consideration when selecting a bore size. The next step in choosing the bore size is the amount of force that the application requires. Suppliers often provide charts to assist with calculating bore size. If the bore diameter is between sizes, fluid-power experts recommend rounding up to the next size. It’s also important to remember the bore diameter squares the thrust delivered. For example, a two-inch diameter cylinder has four times the power of a one-inch diameter unit. Therefore, doubling the bore quadruples the thrust.

In addition to load, designers must also take into account the speed at which the load will move. When compressed air flows through a system, there are pressure losses due to friction against the tube wall, flow around bends, and restrictions in valves and fittings (to name a few issues). Higher speeds result in greater pressure loss as the air must flow faster through the valves, tubing and ports. Attaining higher speeds also requires that the cylinder deliver more force in a shorter amount of time. A force that exceeds the load by 50% or more may be required to reliably move a load at high speeds. For example, a typical air compressor might supply air to a system at 100 psi. In an application with a slow-moving load, the actual pressure available at the piston might be reduced to no less than 90 psi. With that same load moving at a much faster rate, the available pressure could drop as low as 70 psi.

Pressure losses can be remedied by increasing pressure, but this must be done with caution: Too much pressure creates stress on the cylinder and could possibly damage the cylinder, as well as the load. In these instances, it’s better to go with a larger cylinder. Also keep in mind that raising system pressure means the compressor must work harder, increasing energy consumption of the overall pneumatic system.

(From Internet)

Pneumatics are used in many of today’s industrial and automation environments, and there is an increasingly wide range of options from which to choose your components. Knowing how to choose pneumatic fittings is therefore all about suiting the materials to the job and its environment. In order to break down this process, you first need to identify:

• the specific environment in which your equipment will be working

• the required air pressure or PSI specification of your equipment

• any approvals that may be needed for the equipment and its components

• the material(s) from which your fittings should be made

• the type and size of tubing you will require

• the type and size of thread your fittings will need

Solenoid valve selection guide

Before choosing a type of solenoid valve, sufficient information about the application must be gathered. This guide describes the key parameters for solenoid valves.

Important Information

These are the most important guidelines when selecting a solenoid valve. Keep these guidelines in mind before choosing a valve.

• Solenoid valves are very sensitive to dirt and only work with clean liquids or air.

• Note that indirectly controlled solenoid valves require a permanent pressure differential of around 0.5 bar to function properly. Therefore, you can not use indirect operated valves in a closed circuit or systems with a low inlet pressure. Direct and semi-direct operated valves operate with a pressure differential from 0 bar.

• Make sure that the used medium and temperature are compatible with the materials of the valve, such as body and the seal materials.

• Solenoid valves open and close fast (between around 10 and 1000 ms). Improper use can cause pressure transients in the system (water hammer).

Principle of operation

There are different types of solenoid valves, each with different principles of operation:

• Direct operated (operating from 0 bar)

• Semi-direct operated (operating from 0 bar)

• Indirect operated (pressure differential required, normally at least 0.5 bar)

It is important to choose the right operation principle. Direct operated valves operate from 0 bar. In the valve there is a small orifice which is sealed off by a plunger with a polymer gasket. If the solenoid (electromagnet) is electrically energized, the plunger is lifted by the electromagnetic force and the valve opens. This principle is often used for small valves and is suitable for small flow rates. For larger flow rates, a semi-direct or indirect operated valve is recommended. Both make use of the medium pressure to open and close the valve. Semi-direct operated valves operate from 0 bar and often have a more powerful coil than indirect operated valves. Indirect operated valves need a permanent pressure differential of around 0.5 bar for proper operation. The advantage of indirectly operated valves is that they usually can control large flows with a relatively small coil and thereby have a reduced energy consumption.

Check if there is a permanent pressure differential over the valve of at least 0.5 bar. In this is the case, an indirect operated valve may be chosen (a semi-direct valve is of course also allowed in this case). If this is not the case (low inlet pressure, closed circuit, ..), choose a (semi-)direct operated solenoid valve.

 

from Internet

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Post time:        May-03-2022

Description of filter working principle:

The compressed air from the inlet is strongly rotated through the tangential gap of the guide plate. The liquid oil, water and solid pollutants are thrown to the inner wall of the cup by centrifugal force, then flow to the bottom.

The compressed air has removed the liquid oil, water and large particle impurities, and further removes the small particles through the filter element, then flows out from the outlet.

The baffle prevents the liquid oil and water below from being swept back into the airstream. The condensed water accumulated in the cup can be discharged from the drain by pressing the manual button.

You may still will encounter many problems in the actual use process, even fully understanding the working principle.

TIPS1: replace the filter element in time

When the pressure difference between the air inlet and the air outlet is greater than 0.1MPa, or the service time is more than 2 years. Be sure to replace the filter element!

Tips 2: Distinguish between normally open and normally closed drains

There are automatic drain and manual drain, normally people prefer automatic drain. There are two kinds of drainage specifications for automatic drainage: normally open and normally closed.

But normally open is not equal to normally leaky

Tips 3: Installation required

Pre-blow before assembling, to prevent debris, dust, and sealing materials mixed into the compressed air.

The inlet and outlet can not be installed in reverse. And filter need to be installed vertically, with cup downward and make space for maintenance.

The front section of the filter should be equipped with a choke valve for maintenance.

The drain pipe should be secured to prevent the discharge speed from being too fast during the drainage process, which may cause the pipe to swing and injure people.

Tips 4: Strengthen the maintenance

Check the cup regularly for cracks, to prevent cracking and hurting people.

Ordinary cup is made of carbonate polyester. It need to avoid being used with organic solvents and chemical fumes. If you have to, choose a nylon or metal cup. And metal cup is necessary at high temperature.

Avoid the sunshine when using it.

Thread type

Thread size is governed by standards, including BSP (British Standard Pipe) and NPT (National Pipe Thread), although there are many other international standards, and sometimes it depends on the industry and/or country of use. Thread size is always measured and formulated on the interior diameter of the conduit and corresponds to a specific number of threads per inch (TPI). The conduit size is measured in metric (mm) or imperial (inches), and proper sizing is critical, as over- or under-sized fittings will either be wholly incompatible or make an inadequate connection or seal.

The table below shows nominal thread sizes with corresponding values.

 

 

from Internet

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Post time:        Apr-02-2022

Dear all friends and customer,

Happy Chinese New Year

We BLCH pneumatic Team

wish you lucky in the year of OX

safety & peace all the year round

Good health &Vitality

Flourishing wealth & fortune

we will come back from holiday after 20th Feb.  Thanks for your support in the new year!

One of the important parts of the pneumatic components is the cylinder. In order to ensure the normal use of the cylinder and avoid unnecessary situations, for the use of the pneumatic components and cylinder, let’s check the right way to use cylinder. When using the cylinder, the air quality requirements are very high. Clean, dry compressed air should be used. The air should not contain organic solvents, synthetic oils, salts, corrosive gases, etc., in order to avoid bottle and valve failure.