In industrial production during operationpipelines, various types of pumps inevitably lead to losses of pumped liquids. Prevent these cases are numerous seals, one of which will be discussed in detail in this article.
Modern pumping equipment is completeda large number of items. At the same time, the specificity of the work requires paying special attention to the normal and uninterrupted functioning of the products as a whole. Due to the simplicity of their design and ease of use, sealing of pump seals is used much more frequently than other sealing devices.
Impeller of all types of pumpequipment works thanks to the motor. Most often it is electric. Through the mechanical coupling, energy is transferred from the motor shaft to the impeller, which sets it in motion. The shaft itself extends beyond the equipment casing, which makes the casing untight. Therefore, the loss of working fluid is inevitable.
If, however, seal seals of pumps are used, the leakage of the pumped liquid can be avoided. The following technologies are used:
Stuffed (stuffing) seal. It is a ring of fibrous material.
Cuff.Elastic materials are used for such compaction, which can be reinforced to increase rigidity. Used for installation in pumping equipment with a low speed of rotation of the shaft.
Face. Consists of two rings, tightly located to each other on the shaft. One of them rotates with the shaft, and the other remains completely stationary.
Щелевое. Второе название – лабиринтное.It is considered the most reliable modern type of seal. Presented in the form of a ring of soft alloy. It is used in multistage pumps, where the use of other technologies can significantly affect the efficiency.
In addition, there are devices that do not require seals, such as pumps with a magnetic coupling and a wet rotor.
Slotted materials are most often used forensure the tightness of submersible pumps. They do not have special requirements for leakage of liquids. Here the big role is played by the duration of operation.
Seals seals pumps appearedalmost at the same time with the equipment itself for pumping liquids. These are peculiar rings of fibrous material, which are in the gland base, whence their name came. Packing should be moistened with fluid transported through pipelines. This is necessary for cooling and lubrication of the gland. The wetting itself is fraught with fluid loss. Hour pump operation involves the loss of 1-15 liters of water. If the packing is not wetted, then the material will lose the expediency of use, will quickly “burn out”.
You must constantly maintain the seals.Compressors and pumps can not disassemble, which is one of the significant advantages of seals. Self-care is a periodic “tightening” cuff.
The modern market offers a variety of seals for pumps; Typical glands are represented by two main types:
The packing is reinforced with one edge. The main purpose is to prevent losses of the pumped liquid.
Cuffs reinforced boot and one edge. Used to protect the compound itself from dust and dirt. Also, do not allow liquids to leave the transportation system.
If we consider the method of production, we can distinguish the seals:
with molded edge;
with a mechanically-edged edge.
Depending on the type of rubber used there are such cuffs:
Based on nitrile butadiene rubber.Products are made from 1, 2 and 3 classes of rubber. They are characterized by a relatively high threshold of negative operating temperature (-30, -45, and -60 ° C, respectively).
Based on fluororubber. Raw materials - rubber groups 1 and 2. When pumping mineral or transmission oil can withstand temperatures up to 170 ° C.
Silicone rubber. In the manufacture of used rubber only 1 group. The lower limit of the working temperature of the gasket -55 ° C.
As a rule, modern cuffs come complete with springs. They are suitable for sealing on shafts of different diameters.
The spring can be supplied separately from the gland, if you intend to work with a shaft up to 20 mm or more than 120 mm.
Cuffs are usually different.seals with its flexibility and plasticity. High wear resistance is also a significant advantage of products. Minor impact on the shaft extends the application segment.
Performance characteristics are directly dependentfrom the structure of the seal and the composition that was used in production. Depending on the weaving, there are diagonal (through and combined) glands and single-layer seals (meaning the structure of the core). The composition of the cuff are:
asbestos and non-asbestos;
dry and impregnated (fatty, graphite and adhesive mixtures are used as impregnation);
reinforced and unreinforced.
Seals are used to seal the connection.centrifugal, piston pumps and hydraulic presses. The packing can also be used in plunger equipment for pumping a liquid medium. At installation of a product it is worth remembering that pumps with omental consolidations will pass the certain amount of liquid mentioned above.
This is a type of cuff for pumpingequipment. The use of this type of seal completely eliminates the ingress of working fluid into the equipment motor. Where are graphite-ceramic seals used? There are not so many water pumps to which the mechanical seal is suitable. As a rule, the segment of use is limited only by surface mechanisms.
Service life can reach 10 years. In this case it is necessary to adhere to the proper operation of the pumping station. The main requirements put forward at the time of operation of the equipment:
Lack of "dry running". It is strictly forbidden to keep the pump in the "on" mode if there is no liquid in the system.
It is best to pump the most purified substance. The presence of impurities shortens the life of the cuff.
Be sure to adhere to the temperature.
Cuff equipment for pumping water looks,like braided square lacing. Asbestos (cotton or bast) thread may have inclusions of copper or brass wire. Water seal pump seals have a lead core. The size of the tape is 5 * 0.5. Instead of it can be used weaving 4 lead wires.
Water seals are used asusually on the suction side. But it is not excluded their use from the opposite side. The packing size is directly related to the shaft diameter. The maximum number of seal rings is 5.
Seal selection is carried out according to a number of characteristics.Without a doubt, the most important question remains reliability. Among other, important criteria is considered the cost. Additional parameters that are taken into account when choosing devices:
the number of operating hours;
fluid loss;
shelf life;
costs incurred in case of repair.
In addition, the selection of seals for pumps is carried out taking into account sizes. These include the outer and inner diameters, the height and thickness of the base.
Many have already faced the installation of the gland for a single-stage pump. Often, the universality of the packing is noted. The use of seals is not limited to high-speed shafts.
It is noted that the sealing glands pumps with silicone-based lubricant exhibits greater thermal stability.
High carbon variationssignificantly reduce the degree of expansion with increasing temperature of the pumped liquid. And aramid fibers with special impregnation of PTFE allow the gland to work in an aggressive environment in the chemical industry, CHP and in the paper industry.
