The stuffing box of the pump. Stuffing box design

During the operation of the pump, fluid loss occurs. As a rule, this happens at the place of its connection to the pipeline. To avoid this, it is necessary to use a stuffing box for the pump. It is about this adaptation will be discussed.

Pump Seal Packing

Various modern structural elements and parts are installed on modern centrifugal deposits. In this case, it is necessary to ensure the normal functioning of not only individual elements, but also all equipment. The stuffing box of the pump is used more often than other methods. The reason for this is the simplicity of the design, as well as easy installation.

Requirements for the seal

Household pumps work thanks to the impeller, which operates from the engine. As a rule, it is electric. Rotation of the impeller is due to energy coming from the motor through a mechanical clutch. The motor shaft is not in the housing. Therefore, its integrity is impaired. This causes leakage of large amounts of liquid. If you use a stuffing box pump, the problem can be avoided. Today, various methods are used:

1. Printed seal. It is a round structure consisting of fibrous material.
2. Lip seal. As a given sealant, materials that work well for stretching are used. To increase the rigidity of the structure, reinforcement is used. This type is installed on household pumps, where the shaft rotation speed is low.
3. Slot seal. It has another name - labyrinth. This is the most reliable type of seal. It is a round structure made of soft material. This type is mounted on multi-stage pumps. If other seals are installed on them, this will result in loss of unit capacity.
4. End gland packing. This type is presented in the form of two rings, which are densely located to each other. The first performs rotational movements together with the working shaft, and the second is static.

There is such a pumping equipment where the use of a sealant is not required. These are devices that contain a magnetic clutch.

Sealing operation

The stuffing box seal of the pump is used to ensure tightness. As a rule, they are used for submersible types, since they are not subject to special requirements for fluid leakage. In this case, a longer service life is more important.

Packing glands have appeared on the market together with liquid handling devices. Why are they so called? The sealant has a circular shape consisting of a fibrous material. This form is made on a stuffing box. Fibrous material must be permanently wetted by a pumped liquid. It acts not only as a lubricant, but also as a cooling material. Therefore, fluid loss can not be avoided. One hour of work consumes up to 15 liters of water. If you do not wet the fibrous material, it will quickly burn out and you will have to install a new one.

It is worth noting that the elements need constant maintenance. Replacing the stuffing box is done without parsing the pump and the engine. This is a significant advantage. You do not need to call a specialist. Tightening the cuffs is done by yourself.

Stuffing box design

To date, a wide selection of packing glands is available on the market.

The main species are:

1. Reinforced material with one edge. Serves to prevent leaks.
2. Reinforced cuffs with one edge. This device is used to protect the oil seals from dirt, as well as from loss of fluid during pumping.

In addition, the edge can be produced in several versions:

• Standard;
• With machining.

Seals are also divided by the kind of material for the rubber used in the cuffs. Among them are the following materials:

• Rubber. From this material are made different classes of rubber. Their main advantage is the ability to withstand low temperatures.
• Fluoroelastomer. Used only for tires 1 and 2 classes. They are able to withstand temperatures up to 170 ° C, which is achieved when pumping viscous oil.
• Silicone. It is applied only for rubber of 1 class. Can withstand temperatures up to -60 ° C.

Modern cuffs produce together with a spring, which is needed to seal shafts of different diameters.

Characteristics of the sealing material

Compared to other seals, the cuffs have flexible and ductile properties. Operational features depend on the type of sealing material. Depending on the structure, they can have diagonal weave and in the form of a heart. Their composition is also different, and can be this:

• May contain asbestos;
• Be in a dry or impregnated form;
• Reinforced and unreinforced.

Packing glands of centrifugal pumps and hydraulic presses are also used . During installation, it should be taken into account that some of the pumped liquid will be used to wet the seal.

Advantages of the gland seal

So, the cuff serving for pumping liquid, looks like a braided rope. The threads are made of asbestos or cotton. Sometimes they insert copper wire. The middle consists of lead. At weaving can be used from 4 threads.

Seals on the suction side are installed. However, they can be mounted in other places. The amount of packing depends on the diameter of the shaft.

How is the stuffing box selected?

Before buying a seal, it is necessary to consider a number of characteristics. The first and most important issue is the reliability index. Another important factor is cost. Other criteria include:

• Operating time;
• Specific index of fluid loss;
• life time;
• Repair or replacement costs.

Select packing gland is necessary, based on the standard sizes. Here look at the outer and inner diameter, as well as the thickness of the walls.

Reviews

Many users are happy with the stuffing box seal. Using it to mount a single-stage pump, they noticed that the seal is suitable for any shaft speed. The most popular model are seals with lubricant made of silicone. They are able to withstand high temperatures. Some fibers are treated with a special liquid, which allows the use of a sealant for transferring aggressive media.

Users pay attention to the design of the seal. The cuff consists of a woven asbestos thread. When it is made, copper wire is also used . This combination makes it sufficiently strong, and it does not undergo the action of the pumped liquid.

Cost

As mentioned earlier, when choosing a sealant, some characteristics should be taken into account. They affect the cost of the device. Their price is in the range from 100 to 500 rubles.

Conclusion

In order to avoid large leakages of liquid, use gland seals. They are performed in different versions. Of course, there will be a loss of fluid, but it is small. The volume will be spent on wetting the sealing material. Many users are happy with this device. As a rule, it is put on submersible pumps used for pumping dirty water. Their service life is quite long, and the reliability is high. For a fairly small price you can buy quality material that will last a long time.

So, we have examined what the packing glands of centrifugal pumps serve for, and on what types they are divided.