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

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

    Time is flying, in an instant, half a year of 2020 has passed. Enterprises and employees even all of the world have undergone a new test in the past six months due to the COVID-19.

    In the beginning of 2020, affected by the epidemic situation, the company’s commencement date has been postponed again and again. With the support and one month’s arduous straggle of company’s leaders, company finally started operation on 22 February successfully.

  In order to meet the supply needs of customers, we have been continuing to work overtime with quick respond to deliver high-quality products to customers.

The expert review meeting named “Internal Pilot Type Precision regulator” of Zhejiang manufacturing group standard, which was leading by our company successfully held in April.

Affected by the epidemic situation, the safety production monthly meeting of the company was held on May 4. But we have never relaxed our vigilance about safety in production.

On June 23, 2020, Ningbo Fenghua District pneumatic industry association youth branch held a salon activity in our company. We have exchanged many acknowledge with Yueqing and Fenghua’s ” HYDRAULIC-PNEUMATIC MAN” as well.


Even though the half year of 2020 is over, in the following six months, let’s keep going on with high enthusiasm for work.

WE PASS TOGETHER !

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.

Select the correct cylinder according to the following conditions:

1. According to the type of cylinder:

Choose the type of cylinder according to the working requirements and conditions.  Use a heat-resistant cylinder in a high temperature environment.  In a corrosive environment, the use of corrosion – resistant cylinder.  Install a dust cover on the protruding end of the piston rod in harsh environments such as dust.  When no pollution is required, the cylinder without oil or oil lubrication should be selected.

2, according to the size of the force:

According to the size of the load force to determine the cylinder output thrust and tension.  In general, the acting force of the cylinder required by the theoretical equilibrium condition of uniform external load is multiplied by the coefficient 1.5~2.0, so that the output force of the cylinder is slightly surplus.  The cylinder diameter is too small, the output force is not enough, but the cylinder diameter is too large, so that the equipment is cumbersome, the cost increases, and increases the consumption of gas, waste energy.  In the fixture design, should try to use the expansion mechanism, in order to reduce the cylinder size.

3. According to the stroke of the piston:

And the use of the occasion and the stroke of the mechanism, but generally do not choose full stroke, to prevent the piston and cylinder head collision.  If used for clamping machine structure, it should increase the allowance of 10~20mm according to the calculation required stroke.  It should be selected as standard trip as far as possible to ensure the supply speed and reduce the cost.

4. According to the movement speed of the piston:

Mainly depends on the cylinder input compressed air flow, cylinder inlet and exhaust port size and pipe diameter.  High speed motion is required.  The cylinder movement speed is generally 50~1000mm/s.  For high-speed motion of the cylinder, the intake pipe of large internal passage should be selected;  For the load changes, in order to get slow and steady speed, can choose with throttle device or gas-liquid damping cylinder, it is easier to achieve speed control.  When selecting throttle valve to control the cylinder speed, note that: when the horizontally installed cylinder pushes the load, it is recommended to use exhaust throttle speed regulation;  When vertically installed cylinders lift loads, it is recommended to use intake throttle speed regulation;  When the stroke is required to move smoothly to avoid impact, the cylinder with buffer device should be selected.