Method and Model Determination for Fault Diagnosis of Self suction Centrifugal Oil Pump

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Methods for Fault Diagnosis of Self suction Centrifugal Oil Pump

Self suction centrifugal oil pump has a wide range of uses, and the parts and causes of faults that are prone to occur are also different in different industries and environments. In order to cover a large range of fault diagnosis and analysis, the author believes that signal collection and preprocessing methods can be used. This method, combined with signal conversion data, is easy to process and can also form graphics for fault analysis.

The commonly used methods for troubleshooting vibration signals include spectrum analysis, vibration over limit analysis, waveform analysis, axis analysis, etc. Taking spectrum analysis as an example, this commonly used method is introduced:

Spectrum analysis is a method of converting time-domain signals into frequency-domain signals for analysis. During the operation of a self priming centrifugal oil pump, both vibration signals and noise signals can be processed in the frequency domain to obtain images that identify fault characteristic information. For example, most mechanical vibrations are a single sine wave, while in abnormal situations, they manifest as chaotic waveforms of various signals

First, you need to have a preliminary understanding of the principles of spectrum

Firstly, analyze the method of distinguishing between high frequency, medium frequency, and low frequency bands to gain a preliminary understanding of the location where the fault occurred

Secondly, by analyzing the fundamental frequency, superharmonics, and subharmonics, it is possible to determine where the fault occurred in the rotor and what the characteristics of the fault are

Thirdly, analyze according to the sources of frequency components. Due to the fact that the spectrum contains many components, in addition to the fault components superimposed on the spectrum, it also includes various types of noise and noise

Fourthly, analyze according to frequency characteristics. The vibration characteristic frequency is the component in the operation of vibrating parts. As long as there is sufficient understanding of it, the vibration characteristics of different components can be mastered, and then the fault characteristics can be obtained

[2] Determination of Model of Self suction Centrifugal Oil Pump

1. Precautions for Selection

(1) The process flow of the pump should be reasonably determined according to the needs of the process. Basic parameters such as flow and head should generally be considered, such as normal wear and tear of the pump, changes in speed, and a decrease in head. The pump head can have a margin of 2% -5%, but the larger margin should not exceed 10%. The basic principle is that the pump is operating in the area, and the pump state information is used to calculate the installed cavitation margin.

(2) The corrosiveness of the medium and the selection of materials, due to the diverse types and characteristics of chemical media, accurate characteristic parameters are required, not only for metallic materials, but also for the interaction between non-metallic materials and the medium

(3) The temperature of the medium has a significant impact on the structural selection of chemical pumps, such as the pump body support method and the design of cooling (or insulation) systems

2. Pump Type and Parameter Determination

There are nearly 20 types of API self suction centrifugal oil pumps.

. For self priming centrifugal oil pumps, it is suitable for situations where the gas content is less than 5% and the viscosity is less than 650mPa · s. For pumps with larger head, pumps or series pumps can be used. For pumps with larger flow, double suction pumps, mixed flow pumps, or parallel pumps can be used. For fluid media with fine particles, the use of open or semi open impellers can prevent impeller blockage, but the corresponding performance may decrease. When the conveying medium is toxic or radioactive, a magnetic drive pump can be selected. For the delivery of valuable or important fluid media, a shielded pump can be used for situations where it is not necessary to recite a single drop. According to the on-site installation conditions, choose a horizontal pump or a vertical pump. For underwater use, a submerged pump should be considered comprehensively for special situations

3. Confirmation of pump shaft seal

The shaft seal forms of self suction centrifugal oil pumps mainly include packing seal, mechanical seal, and dynamic seal.

. It is necessary to fully understand their respective advantages and disadvantages in order to determine which type of seal to match the selected self suction centrifugal oil pump

(1) Packing seal: The advantages of packing seal are simple structure, low cost, convenient maintenance, and low processing requirements. The disadvantages are short lifespan, large leakage, and high wear and tear power consumption

(2) Mechanical seal: Mechanical seal, also known as end face seal, is a dynamic seal used for rotating shafts. The advantages are performance, small leakage, long service life, low power consumption, and no need for frequent maintenance. It can also adapt to the dynamic sealing requirements of production process automation and harsh working conditions such as high temperature, low pressure, high pressure, vacuum, high speed, and various strongly corrosive media, media, and media containing solid particles. The disadvantage is that the price is high, the processing and maintenance requirements are high, and it is difficult to handle accidental accidents

(3) Power seal: The advantages of power seal are performance, low price, and easy maintenance. It is generally used in situations where mechanical seals are difficult, such as under conditions with abrasive particles and strong corrosion; The disadvantage is that the power loss is greater than that of mechanical seals, and the lifespan of parking seals is shorter. The pump using power seal should have a pressure less than 10% of the outlet pressure