Fault Analysis and Elimination of Vacuum Standard Devices

Failure analysis and elimination of vacuum standard equipment Wenmei work unit Dong'an Engine Group Co., Ltd.

Communication address 150066 Harbin No. 51 Mailbox Measurement Institute.

Yan Dongsong, Dongan Engine Group Co., Ltd. made a brief description of the quasi-measurement device, mainly introduced the failure analysis and elimination of the device.

Quasi-apparatus, Type 38 vacuum standard device adopts the method of combining dynamic and static 4 expansion, and combines the basic method of dynamic gauge and static expansion of two verification vacuum gauges into a standard vacuum device, which replaces glass expansion. System and Glass Pay System. The metallization of the vacuum standard is realized. It is a kind of vacuum standard with simple structure, easy operation and high efficiency, and practicality. The main technical indicators conform to the requirements of national standards, and various types of vacuum gauges capable of calibrating 105,05 are currently advanced. The standard vacuum device.

The principle of the compound vacuum standard device is compounded by two basic methods of verification vacuum gauges. The comparison calibration is to connect only one or more vacuum gauges and auxiliary vacuum gauges to be calibrated to the calibration container. When the pressure in the calibration container reaches equilibrium, the pressure calibration points are adjusted, and the vacuum gauge and the seized vacuum gauge are used. The vacuum gauge measures the same pressure in the calibration container, compares the measured results directly, takes the reading of the secondary standard as the standard, and outputs the correction coefficient or calibration curve of the vacuum gauge to be inspected. The expansion method calibration is to charge the sample gas into a known small volume, and then expand it isothermally to a known large volume. Finally, the standard pressure is calculated according to Boyle's Law=72.

The principle of the calibration device 1. It is composed of the electronic control part of the metal expansion valve of the standard container substandard vacuum gauge and the standard expansion device of the hydraulic wheel. 2 The leakage fault and analysis of the standard device 2.1 The standard device startup failure When the standard device was started in October 2001, Valve 2 valve 4 suddenly loses control and cannot start, causing the verification to stop.

Fault analysis valve 2. Valve 4 is a solenoid valve, and electromagnetic is mainly composed of valve body and electronic control part. The valve body part is made of stainless steel metal material, the wearing part is the valve core, and the electronic control part also needs to detect 2 solutions. Valve 2 valve 4 power supply, valve 2 has the sound of the suction of the relay, and valve 4 there is no sound, you can conclude that valve body valve 2 is damaged, Ke 4 is part of the power failure.

Points, the connecting rod and the piston of the valve core are broken, and the core is replaced, and the test is repeated item by item, and the capacitance is found to be damaged after being broken down. Replacement of the same type of capacitor, but can not be purchased at the moment, 18 factory 0 type relay, due to the production of emergency, on the deduction, 13 models for the factory to find generation, 2.2 standard device leakage fault analysis and maintenance due to the standard device vacuum The degree is higher and can reach 1043. Therefore, it is required that the system has extremely strong side contacts and the fittings are complex. It is easy to arch vacuum leakage.

After the solenoid valve was repaired, the standard device was started. After the mechanical pump was opened, the system was found to be running for a long time. The vacuum gauge connected to the calibration chamber had no vacuum level indicator.

Leakage can be divided into two cases, one is that the leakage rate is small and it is within the allowable range.

That is to say, although there is a leak, the required degree of vacuum can be maintained in the system through continuous operation of the vacuum pump. In addition, the leakage rate is relatively large, and the vacuum degree of the system cannot meet the requirements.

There is a leak, the device vacuum cannot be pumped up, which is often analyzed by two major factors to explain the leakage phenomenon of the device. The main reason is that the front-stage pump mechanical pump 3 device is leaking due to our existing inspection. Leakage conditions are limited, the leak location of the device is not easy to find, you must find a key part of the leak.

The low-level decimating equipment for testing and repairing the mechanical pulp standard equipment is the 274 rotary blade type mechanical mining. Call the foreline pump. Pump pumping rate printing = 07 households = 4 ultimate vacuum sub-vacuum 6.01 fault phenomenon with a thermocouple vacuum gauge connected with the mechanical pump, start mechanical pumping, the vacuum gauge is not 8.03. Description of its performance has declined.

0 Solve and disassemble the pump. Remove debris inside the pump.

Clean all parts with alcohol, especially the filter screen, replace the rubber seal of the inlet pipe and the joint, and start the mechanical pump after Zhuoxin. The thermocouple vacuum juice quickly indicated that its enamel could return to normal. Reinstall the mechanical pump and start it. The standard low vacuum gauge 03 digital display indicates that the 0.001 vacuum low part is working properly. Simultaneously. It was found that the mechanical pump worked for a long time. The vacuum gauge to be inspected remains at 35.09 and remains there for a long time, indicating that there is a serious air leakage fault in the high vacuum section.

Test and repair the calibration chamber in order to find the location of the leak in the calibration chamber.

According to the conditions we have in hand. Inflatable detection.

Apply a thin layer of soap to the tubing connections outside the calibration room and fill the calibration chamber with dry nitrogen. For example, bubbles appear.

It proves that the location is leaking. Carefully and patiently observe the interface outside the calibration room. After 56 minutes of observation, no bubbles appeared. In other words, the calibration chamber has good sealing performance.

(4) Test Overhaul Vacuum Two-way gate valve Due to the performance requirements of the standard device, when the two-way alarm valve is opened, it must be ensured that both sides of the core are started under vacuum or atmospheric pressure. Adjust the regulator valve to inflate the regulator bottle. Open the valve 4 valve 2 so that gas enters the molecular pump and the internal pressure is adjusted to the atmosphere. The adjustment face seal air regulating valve inflates the calibration chamber to the atmosphere. When the vacuum two-way valve is on both sides of the gas balance state.

Close the valve 4. Open the gate valve and start the mechanical pump.

To vacuum gauge like quick to 4.01 When closing the gate valve, the vacuum gauge quickly returns to the initial point.

The change in pressure over time is observed by the vacuum 1 attached to the system. Record data and plot it. After the mechanical pump is cut off, the pressure of the system rises linearly and can rise to balance with the external atmosphere.

Leakage rate from the perspective of the leakage rate analysis of the leak rate refers to the specific conditions under the conditions of a particular gas off through the leaking brother. The formula for the combination of 2 can be small. Seven is big, factory set.æ±² 1 is very large, that is, the leakage rate is large.

starting time. Because of the fast time. The pressure changes greatly.

Its leakage rate is larger. Therefore, the device has a serious air leakage phenomenon. The above test results showed that the 265 嘈 vacuum double used in the device had the performance and structure of the bidirectional sealing of the ram valve. Asked that we must determine the side of the leak, repeat the above experiment. Start the mechanical pump, vacuum gauge means 4.0 hours. Close the gate valve.

Make the mechanical pump work properly. If the bottom of the gate leaks. With the continuous operation of the mechanical pump, the vacuum degree of the system + will drop a lot. However, in the experiment, it was found that the vacuum gauge soon returned to its initial point, which was certain that the upper layer of the gate valve was leaking.

1 Symptoms There is broken glass powder inside the gate valve body Friction rubber on the surface of the farm has scratches on the valve seat, the shape of the seal ring degeneration valve plate assembly ball only heavily worn bolt positioning misalignment of the mediator.

2 Solution Remove the driver of the driver board and the latch positioner, remove the fine glass powder from the valve body, clean it with alcohol, and dry it. When the valve is in the open state, remove the cover cap fastening screw and install the valve plate assembly and the example. Cover and remove. Re-evaluate it. Surface plating and special treatment. Improve the smoothness; replace the top layer of the modified seal, the shape of the apron; replace the new steel ball; select the knurled handwheel with the clutch into the conversion. First rotate the knurling handwheel at an angle. Then move the clutch of the plug positioner. Make multiple surveys. Determine the position of the latch positioning clutch. After the valve is repaired, reinstall it. Once the mechanical pump is actuated again, valve 4 is bypassed. After 18,1, the standard low vacuum gauge, 3 digital reference is 0.001. The vacuum gauge in the connection calibration chamber is 9.03 to close the bypass valve, and the molecular drag control is activated. After it is operating normally. Open gate valve thermocouple good-natured in 2 blood within the finger into (1) standard ionization vacuum gauge refers to a factory 31 to close the alarm board valve. In the calibration chamber, the air volume varies with time. 2 Curve 2 After the gate valve is closed, the vacuum pump is switched off. The pressure of the system gradually rises, and the pressure sweat is close to (1). The leakage of the system from the line sentence can be within the allowable range, that is to say, the performance of the standard mounting device meets the conditions required for regular operation, and it reaches our maintenance equipment. 3. Concluding Remarks After careful and detailed analysis and analysis And measurement, ruled out the failure of the vacuum standard device. Guaranteed vacuum. The reliability and continuity of the standard device delivery. ,Time. Has also gained a lot of practical experience. We have accumulated useful information for the subsequent maintenance.

1 Liu Hongqing. Vacuum metering. Beijing China Measurement Publishing,

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