Where is ball valve ⅜ used - criteria for selecting shut-off valves

Shut-off valves play an important role in the proper operation of pipe lines.Elements such as valves, taps, gate valves and others make it possible to hermetically shut off the movement of liquids and gases through pipes, if necessary. One of the popular types of shut-off valves used in household networks is a 3/8 ball valve.

What is a 3/8 ball valve?

All locking devices, including the ball model, consist of three parts:

• cylindrical body;
• a ball with a slot or hole (through) - located inside the body;
• a rod, which is attached to the ball on one side and to the lever on the other.

The latter performs the functions of a rotating device. Turning it first one way or the other, the internal space ball valve can be closed or opened.

This is exactly how a ball valve should work. It cannot be used to regulate liquid or gas flows inside the pipeline (throttle them). If this is done due to ignorance or other reasons, the fittings quickly fail. It is not difficult to determine that this caused the defect. Such ball valves are not covered by warranty repair.

The rod goes through the body, but the lever is outside it.In order not to make a mistake with the adjustment, in the factory these parts are assembled in such a way that if the latter is located along the valve body, this means that it is open. Liquid or gas can move inside it. If the location is transverse, then the ball valve is closed.

The ball type of shut-off valves was invented a long time ago. But it was not possible to use it due to the poor quality of the seals. Today, there are several high-quality sealing materials that are used in the design of ball valves:

• synthetic nitrile-butadiene rubber (NBR);
• Teflon.

The first is black, the second is either white or yellowish. Lubricants must be added to the seals to increase the performance characteristics of the materials. A frequently used option is graphite.

Structural diagram of ball shut-off valves

Classification of ball valves 3/8

There are several characteristics by which 3/8 ball valves are classified. The first is based on the material of manufacture. There are three groups here:

• steel;
• cast iron;
• brass.

Manufacturers offer ball valves that include polypropylene parts. This is a combination option.

For in-house pipe networks, 3/8 brass ball valves are considered the best. They are manufactured using hot volumetric pressing technology. The starting material is 100% pure or lead-containing brass.

Most models are coated with a galvanic layer, which increases the service life of the ball product. It is silver in color. Therefore, you need to pay attention to the internal surfaces of the tap pipes. If they are yellow, then the element is made of brass. You can rub the surface of the case with sandpaper.If yellowness appears, then it is brass.

Today on the market you can find 3/8 ball valves made of ZAM. This is a zinc-aluminum alloy. The worst option for plumbing. They break down quickly. The reason is zinc corrosion. They can be distinguished from brass ball fittings by their specific gravity. They are lighter.

In the direction of the pipe

The classification is based on the direction of the pipe line, which can be straight or branched. In the first case, a ball valve connects two pipes laid along the same axis. In the second, sections of the network are connected at an angle - usually at a straight line.

Angle ball valve 3/8 is rarely used here. It is better to install a standard straight one and connect the pipes through an elbow or tee.

By modification of handles

There are also two varieties:

• butterflies installed on small-section taps;
• levers for large cross-section reinforcement.

The second design allows it to withstand heavy loads. In this case, it is easier to open the pipeline using a lever.

Ball device butterfly handle

According to the size of the ball fittings

Ball valve sizes are marked in inches. For example, 1 inch is 25.4 mm. Accordingly, 3/8 inch is 9.5 mm. But there are other popular dimensional parameters. Each ball valve is selected to match the diameter of the pipe to which it is connected.

Through the passage hole of the ball device

There are also two positions here:

• full bore;
• partially passable.

In the first, the passage hole of the faucet coincides with the hole of the pipe. Therefore, the passage of liquid or gas through the pipeline is almost one hundred percent. Shut-off valves do not create resistance.

The second is a special solution if it is necessary to limit the volume of liquid or gas inflow. Partially passable ones are divided into two subgroups:

• standard bore. They have a hole in the ball one size smaller than that of the pipe. Throughput – 70-90%;
• incomplete bore. The hole in the ball is smaller than the diameter of the pipe. Low node patency – 40-70%.

By connection method

This refers to the connection to the pipeline. The classification includes 4 positions:

• coupling, they are also threaded;
• flanged;
• welded;
• combined - one end can be welded, the other threaded, and other combinations.

The first option has a conical or cylindrical thread. Typically, such ball valves are installed on pipe sections with a diameter of no more than 50 mm. The thread can be external or internal.

Flanged ones are mounted only on pipe lines with a diameter of more than 50 mm. Separable and non-separable flanges are used. This type of ball shut-off valves is installed in those rooms where it is impossible to carry out welding work. Or where it is necessary to carry out frequent repairs of the site, its dismantling.

The third category includes both steel and plastic cranes. A distinctive feature is the most airtight connection with pipes. Typically, installation of such valves is carried out on external sections of the pipeline.

Flanged ball design

By ball design

There are also 2 positions here:

1. The ball is floating. The design received its name due to the fact that the ball is not tightly connected to the rod - the two parts can move relative to each other. The offset size is small. The ball inside the faucet works like this - the internal water pressure presses the first one against the seal, which creates a high tightness of the structure. In the open state, tightness is not important.
2. Ball in supports. Supports in the form of protrusions are added to the structure. There are two of them - lower and upper.The purpose is to enter the saddles (seats) and secure the ball tightly inside the body. This design reduces the force that must be applied to the lever to open or close the pipeline. But the complexity of the device increases its cost.

The ball is electroplated, which is based on chromium. It is applied to either an aluminum or nickel substrate. If the substrate is not applied, the service life of the coating is reduced significantly.

Some manufacturers offer 3/8 ball valves with a Teflon-lined valve. On the one hand, friction is reduced. On the other hand, Teflon is a fragile material. And since solid particles move in pipelines, they quickly disable it, which leads to depressurization of the ball valve.

What to consider when choosing 3/8 inch ball valves

The most important parameter is the pipe diameter. It is clear that the two diameters (device and pipe) must match.

The second selection criterion is the material from which the ball device is made. Stainless steel is stronger and more durable, but they are expensive. In this regard, brass ones have shown themselves to be excellent in household pipe systems. But you need to take into account what brand of brass they are made of. If this is LS59-2, then you can safely buy the device.

The ball is usually made of stainless steel, but not always. When choosing a 3/8 ball valve, you need to read the product labeling. It is available on all devices, regardless of manufacturer. Usually two parameters are specified:

• bore diameter, designated as Dn;
• the pressure of the working medium that the fittings must withstand is designated Pn.

Serious manufacturers indicate their logo. But the absence of this sign is not an indicator of low quality.

It is important to pay attention to pressure.If you buy a 3/8 ball valve and install it in an engineering system in which the pressure of the flowing medium constantly or briefly increases, then there is a high probability that with low pressure the device will no longer hold the load after a while. He will start siphoning.

Ball valve marking

Ball valve gland assembly

The unit ensures the tightness of the device to the external environment. Preference is often given to designs with an external clamping nut. It has an external thread.

The maintainability of the product depends on the stuffing box. There are 3/8 ball valves, non-separable and collapsible. The first ones belong to the category of non-repairable ones. If they leak, they are replaced with new ones. The second ones can be repaired.

Maintainability makes shut-off valves vulnerable to pressure inside the pipes. In their design, the rod is inserted from the outside and only a union nut holds it in the body. There is a high probability that it will be knocked out under environmental pressure. It is better to purchase 3/8 ball valves, in which the stem is held by a collar from the inside.

Sealing elements also affect the long-term operation of shut-off valves. Today, manufacturers are increasingly using Teflon as the best sealing material. But it is expensive, so it affects the cost. To lower it, unscrupulous manufacturers resort to tricks:

• reduce the thickness of sealing gaskets;
• They use Teflon from recycled materials, of low quality.

Another point is the correct compression of the Teflon seat rings around the ball. If the ball inside the housing rotates freely, it means that the compression was carried out incorrectly. Such a ball valve will begin to leak.

If, on the contrary, the tap opens and closes tightly, then over time, due to the force of friction, the seal will become thin - this will lead to loss of sealing.

Handle attachment

Good fasteners increase the service life of 3/8 ball valves. Look at the photo below.

Handle attachment methods

In this case, option “B” is ideal. The rod is fitted with a polymer gasket. It is installed in tension - its diameter is less than the diameter of the rod head. A nut screwed on top will never come loose under any load.

Option “A” is a mounting screw that is screwed into a hole made at the end of the rod. This is the worst option, because the screw will always be unscrewed. The internal threads will become thinner over time and will no longer hold the fastener.

Option “B” is a regular nut, which will unscrew under the influence of vibration of the pipeline. It will have to be tightened periodically. It is important here to accurately capture the twisting force. If the nut tightens the handle weakly, the latter will create serious loads on the rod during operation, which can lead to its breakage.

Rules for operating a 3/8 inch ball valve

Any shut-off valve, if installed and operated correctly, will last longer than the warranty period. This also applies to the 3/8 ball valve. Since household pipe engineering systems use various media, mostly untreated, there is a high probability that shut-off valves of this type will quickly fail. Therefore it is recommended:

1. Install a mini 3/8 mesh filter in front of the ball valve that will retain abrasive particles. The latter thin the seals, which leads to depressurization of the structure.
2. If this is a threaded model, then the threads on the pipe and faucet should be the same.This applies not only to the diameter, but also to the height, the distance between the turns.
3. If it is impossible to turn the handle, do not artificially add length to it to increase the force. Any mechanical overload on the rod will cause it to break.

Over time, 3/8 ball valves begin to work incorrectly: they leak, it is impossible to turn the handle, they allow the medium moving through the pipes to pass through when closing, etc. If a non-repairable ball model is installed, it will have to be replaced with a new one. If it’s repairable, it’s worth looking into its repair, which basically comes down to replacing the gaskets.

When the coating of the ball has become unusable: rust, dents, cracks, traces of abrasive particles, then there is no point in repairing such a ball device. Better to replace it.

The 3/8 ball valve is an important part of the pipeline. It is installed in water supply, heating circuit and others. In order for a product to last a long time, it is worth considering its material, seals, manufacturer and technical characteristics.

Have you ever chosen or used a ball valve? Share your experience in the comments. Save the article to your bookmarks and repost it on social networks.

We also recommend watching selected videos on our topic.

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Marking of ball valves and valves - what do the icons, numbers and letters mean?

Sources:

• https://aw-therm.com.ua/osobennosti-vybora-sharovyh-kranov
• https://santehstandart.com/poleznye-materialy/kran-sharovyy-3-8