What are the principles and steps of BOD detection?

What are the principles and steps of BOD detection? Determination of BOD5 by iodometry

First, the experimental principle

Iodometric determination of dissolved oxygen in water is based on the oxidation efficiency of dissolved oxygen. When manganese sulfate and alkaline potassium iodide solution are added to the water sample, Mn(OH)2 precipitate is formed immediately. Mn(OH)2 is extremely unstable and quickly combines with dissolved oxygen in water to produce manganese manganate. After adding sulfuric acid for acidification, the combined dissolved oxygen (in the form of manganese manganate) oxidizes KI and releases free iodine equivalent to dissolved oxygen. Then titrate with sodium thiosulfate standard solution to convert the dissolved oxygen content. The difference of dissolved oxygen before and after five days of the same water sample can be measured respectively, which is the five-day biochemical oxygen demand.

This method is suitable for cases containing a small amount of reducing substances and nitrogen nitrate.

Second, the main instruments of the experiment

1.250ml iodine volumetric flask

2. 100 ml iodine volumetric flask

3.150ml conical flask

4. Constant temperature incubator

5. Pipette:12510 2550ml.

6. siphon

7. Titrator

Third, the reagent configuration

1. manganese sulfate solution: weigh 36.4gMnSO4? H2O, dissolved in distilled water, diluted to a constant volume of 100mL. (When this solution is acidic, it will not produce blue color when it meets starch after adding KI. )

2. Alkaline potassium iodide solution: dissolve 500gNaOH in 300 ~ 400 ml distilled water, and keep stirring and shaking (otherwise it will easily become flocculent), and dissolve 150gKI in 200mL distilled water. After the NaOH solution is cooled, the two solutions are combined, mixed evenly and diluted to 1L with distilled water. If there is precipitation, leave it overnight, pour out the supernatant, store it in a plastic bottle, and wrap it with black paper to avoid light.

3.( 1+5) Sulfuric acid solution: Remove 50 ml of distilled water with a 50 ml pipette, then remove 10 ml of concentrated sulfuric acid (analytically pure) with a 10 ml pipette, slowly flow into a beaker containing 50 ml of distilled water, and stir with a glass rod.

4. Concentrated sulfuric acid (analytically pure)

5. 1% starch solution: weigh 1g soluble starch, make it into paste with a little distilled water, and dilute it to 100mL with just boiled water (probably, it is not necessary to accurately determine the volume). After cooling, add 0. 1g salicylic acid or 0.4g zinc chloride for anticorrosion.

6.0.02500 mol/l (1/6k2cr2o7) potassium dichromate standard solution: weigh at 105- 1 10℃, dry for 2 hours, cool and dissolve in water.

7.0.025mol/L sodium thiosulfate solution: weigh 3.2g sodium thiosulfate (Na2S2O3? 5h2o) Dissolve in boiling cooling water, add 0.2g of sodium carbonate and dilute (boiling cooling) with water to 1000mL. Store in a brown bottle and calibrate with 0.02500mol/L potassium dichromate standard solution before use.

The calibration method is as follows:

Add 100mL water and 1gKI into a 250mL iodine volumetric flask, and add 10.00mL 0.02500mol/L potassium dichromate (1/6K2Cr2O7) standard solution and 5mL( 1+5) sulfuric acid. After standing in the dark for 5 minutes, titrate with sodium thiosulfate solution to be calibrated until the solution is light yellow, add 1 ml starch solution, continue titration until the blue color just fades, and record the dosage.

C=

Where: c is the concentration of sodium thiosulfate solution (mol/L).

V refers to the volume (mL) of sodium thiosulfate solution consumed during titration.

Fourth, the experimental steps

1. Water sampling and packaging:

(1), rinse 500 mL water sample twice first, and then slowly flow the water sample into the beaker along the beaker wall. It should be noted that the water flow should not be too fast, and bubbling is strictly prohibited.

(2) PH adjustment: adjust the PH of the water sample to 6.5~7.5 with a PH meter.

(3) Sub-packaging the water sample: insert one end of the siphon into the water sample, siphon out the water at the other end with an ear washing ball, and then slowly flow down the siphon at this end with an iodine measuring bottle, first put it into a 250 mL iodine measuring bottle, and wet it twice before loading it; Then put it into a 100mL iodine volumetric flask. 250 mL iodine bottle mouth should overflow with water sample to ensure water seal, then wrap the bottle mouth with plastic wrap and put it in a constant temperature incubator at 20℃ for 5 days.

2. Determination of dissolved oxygen in water sample in100 ml iodine volumetric flask;

(1) Insert the pipette under the liquid surface, add 0.5mL manganese sulfate solution and 1.0mL alkaline potassium iodide solution in turn, cover the bottle stopper, mix upside down 15 times, and let stand. When the brown flocculent precipitate is reduced to half, it is reversed several times.

(2) When analyzing, gently open the cork, immediately insert the straw under the liquid surface, add 1.0mL concentrated sulfuric acid, carefully cover the cork and shake it upside down until the precipitate is completely dissolved. If the dissolution is not complete, a small amount of concentrated sulfuric acid can be added continuously, but the solution cannot overflow at this time. Then leave it in the dark for 5 minutes.

(3) Suck 50mL of the above solution with a straw, inject it into a 150mL conical flask with a rotor, titrate with 0.025mol/L sodium thiosulfate standard solution until the solution is light yellow, add 0.5mL starch solution, and slowly drop it when it is near the end point, rinse the drug remaining on the tube wall with distilled water, and continue to titrate until the blue just fades, and record the dosage of V 1.

3. Five days later, determine the dissolved oxygen in the water sample in the 250ml iodine volumetric flask:

(1). Insert the pipette under the liquid surface, add 1.0mL manganese sulfate solution and 2.0mL alkaline potassium iodide solution in turn, cover the cork to avoid bubbles in the bottle, mix upside down 15 times, and let stand. When the brown flocculent precipitate is reduced to half, it is reversed several times.

(2) When analyzing, gently open the cork, immediately insert the straw under the liquid surface, add 2.0mL concentrated sulfuric acid, carefully cover the cork, and shake it up and down until the precipitate is completely dissolved. If the dissolution is not complete, a small amount of concentrated sulfuric acid can be added continuously, but the solution cannot overflow at this time. Then leave it in the dark for 5 minutes.

(3) Suck 50 ml of the above solution with a straw, inject it into a conical flask with a rotor of 150 ml, titrate it with 0.025 mol/L sodium thiosulfate standard solution until the solution is light yellow, add 1.0 ml starch solution, and slowly drop it when approaching the end point, rinse the residual drugs on the wall with distilled water, and continue to titrate until the blue color just fades, and record the dosage of V2.

Verb (abbreviation for verb) calculation

Dissolved oxygen (mg/L)

Where: c-concentration of standard solution of sodium thiosulfate, mol/l;

V—— the volume of sodium thiosulfate standard solution consumed during titration, ml;

Molar number of 8- 1/4o2, g/mol;

50- Water sample volume, ml.

The data list is as follows:

1. Calibrate sodium thiosulfate:

No. C( 1/6K2Cr2O7)

(mol/l) Vanadium (1/6K2Cr2O7)

Vanadium (sodium thiosulfate)

(ml) carbon (sodium thiosulfate)

(mol/L) D relative value (%)

1

2

three

Average v scale

2. Calculate the BOD for five days.

Oxygen demand (mg/l) =40(V 1-V2)/V standard.

Principles and steps of molecular biological detection of edible fungi II. Develop and provide machinery for producing various products, including agriculture, forestry, animal husbandry, fishery machinery and mining machinery, as well as various heavy industry machinery and light industry machinery;

3. Develop and provide machinery engaged in various services, such as material handling machinery, transportation machinery, medical machinery, office machinery, ventilation, heating and air conditioning devices, and environmental protection devices such as dust removal, purification and noise elimination;

4. Develop and provide machinery for family and personal life, such as washing machines, refrigerators, clocks, cameras, sports equipment and entertainment equipment;

5. Develop and supply all kinds of mechanical weapons.

Subject content of mechanical engineering

Subject content of mechanical engineering

Steps of soil sample detection:

1, agricultural soil testing generally includes soil fertility station of local agricultural bureau to test soil pH and nitrogen, phosphorus and potassium content;

2, soil solid waste monitoring, environmental protection bureau monitoring station

3. If it is the soil sample detection of earthwork excavation before the project starts, if the excavated soil is no longer used, it is not necessary to carry out soil sample detection. If it is a user, it is necessary to do soil sample testing, which is the same as the soil sample testing of earthwork backfilling you said.

Specific steps of DNA testing paternity test is one of the special items of forensic identification. No matter what the purpose is, it is recommended to go to a local formal judicial authentication institution. For details, please consult the Municipal Bureau of Justice or the Provincial Department of Justice to inquire about the directory of judicial authentication institutions in this province. At present, many institutions claim that paternity testing can be done, so it is recommended to choose carefully to avoid being fooled. The price is generally around 3000, so be careful whether it is too high or too low.

For paternity testing due to immigration, notarization, household registration or litigation, it is necessary to bring the party's ID card or household registration book or birth certificate to the judicial authentication institution for relevant entrustment procedures. For the parties who personally doubt the parent-child relationship, they can bring their own samples (such as blood stains, hair, oral swabs, etc.). ) to handle the entrustment procedures, they can conduct anonymous appraisal without providing personal documents.

The acceptance procedure first needs to sign the entrustment agreement, risk warning sheet, collect the blood samples of the parties and make corresponding video records. Pay the appraisal fee and agree on the way to receive the report.

What are the steps of TOFD detection? There are many controversies in TOFD detection that need to be calibrated. Used for common detection (carbon steel) probe delay, probe front end, blind zone test, PCS, thickness inspection, etc. All need calibration. For the detection of special materials (titanium, nickel, zirconium, tantalum), in addition to the above calibration, it is necessary to test and calibrate the sound speed. It is also necessary to test the converted shear wave for the inspectors who are concerned about the converted shear wave signal. At present, some propagation principles of converted shear waves are worth studying. View original post >>

The steps of motherboard testing are the same as mine. After entering the BIOS, I found that there is a CPU fan speed setting CPU fan monitoring in the hardware monitoring, and the chassis fan speed is used to set the chassis fan monitoring, but it is suggested that LZ should not turn off the fan monitoring, which is safer. .

Detection methods and steps of BOD5 Definition of BOD (Biochemical Oxygen Demand)

English: Biological oxygen demand (BODM and) indirectly expresses water coverage through the amount of dissolved oxygen consumed by microorganisms.

BOD detector

An important indicator of organic pollution. Its definition is: under aerobic conditions, the amount of free oxygen consumed by aerobic microorganisms in unit volume of water for oxidative decomposition of organic matter is expressed in mg/l (O2, mg/L) oxygen. It is mainly used to monitor the pollution of organic matter in water. Generally, organic matter can be decomposed by microorganisms, but it takes oxygen for microorganisms to decompose organic matter in water. If the dissolved oxygen in water is not enough to meet the needs of microorganisms, the water body is in a state of pollution.

definition

The degradation of organic matter by microorganisms is related to temperature. Generally, the most suitable temperature is 15 ~ 30℃, so 20℃ is generally taken as the standard temperature when determining BOD. At 20℃, under the condition of BOD determination (sufficient oxygen, no stirring), it takes 20 days for the general organic matter to basically complete the first-stage oxidative decomposition process (99% of the completion process). That is to say, it takes 20 days to measure the biochemical oxygen demand in the first stage, which is difficult to do in practical work. Therefore, a standard time is specified. Generally, 5 days is taken as the standard time for determining BOD, so it is called 5-day biochemical oxygen demand, which is expressed by BOD5. BOD5 is about 70% of BOD20.

Several sayings of setting it to 5 days

First, because the oxygen consumption in 5 days is obviously mainly organic matter, it will not produce the consumption of other substances such as ammonia nitrogen. Second, this study was first done in Britain. The longest time for all rivers in Britain to flow out of the country (that is, into the sea) is five days. Thirdly, because the biodegradation reached a high proportion within 5 days, the detection was obvious. Fourth, because the five-day working day system, that is, the results can be produced this week, it is set to five days.

decision

Dilution inoculation method (GB7488-87)

This standard refers to the international standard ISO 58 15- 1983. This national standard stipulates that dilution inoculation method is used as the standard method for determining biochemical oxygen demand in water, which is an empirical routine method.

Scope of application: This method is suitable for water samples with BOD5 or 2mg/L and no more than 6000 mg/L. This method can still be used for water samples with BOD5 greater than 6000 mg/L, but the determination results need to be carefully explained, because dilution will cause errors. The result of this experiment is the result of biochemical and chemical action. They are not as strict and clear as a single and clearly defined chemical process, but they can provide indicators for evaluating the quality of various water samples. The results of this experiment may be disturbed by some substances existing in water. Those substances that are toxic to microorganisms, such as fungicides, toxic metals or free chlorine, will inhibit biochemical effects. Algae or nitrifying microorganisms in water may also lead to false high results.

Principle: Fill the culture bottle with water sample, plug it and keep it closed for 5 days. The dissolved oxygen concentration is measured before and after culture, and the oxygen consumed per liter of water, namely BOD5 value, can be calculated from the difference between them. Because most water samples contain more aerobic substances, their oxygen demand often exceeds the amount of dissolved oxygen (DO) available in water, so it is necessary to dilute the water samples before cultivation to make the remaining dissolved oxygen (DO) meet the requirements. Generally, BOD5 measured in water quality inspection only includes the oxygen consumption of carbonaceous materials and inorganic reducing materials. Sometimes it is necessary to measure the oxygen consumption and nitrification of carbonaceous materials separately. The common method to distinguish the oxygen consumption of carbon and nitrogen nitrification is to add nitrification inhibitor to the culture bottle. After adding a proper amount of nitrification inhibitor, the measured oxygen consumption is not only the oxygen consumption of carbonaceous materials. During the five-day culture period, the oxygen consumption of nitrification depends on whether there are enough microorganisms to carry out this oxidation. The number of these microorganisms in raw sewage or effluent from primary treatment is not enough to oxidize a large amount of reducing nitrogen, while many effluent from secondary biochemical treatment and long-term polluted water often contain a large number of nitrifying microorganisms, so the nitrification reaction should be inhibited when measuring this water sample. When determining BOD5, the standard solution of glucose and glutamic acid is needed to complete the verification test.

Reagents: During the analysis, only recognized analytically pure reagents and distilled water or water with the same purity (distilled water or deionized water in all-glass device) are used. The copper content in water shall not be higher than 0.0 1mg/L, and shall not contain chlorine, chloramine, alkali, organic matter and acid.

1 inoculation water

If the sample itself does not contain enough suitable microorganisms, inoculation water should be obtained by one of the following methods:

A. Urban sewage is taken from sewage pipes or residential sewage pipes, and there is no obvious industrial pollution.

Before use, this kind of water should be poured out for later use.

B, add 100g garden soil into 1L water, mix and stand for 10 minute. Take 10ml supernatant and dilute it to 1L with water.

C. rivers or lakes containing urban sewage.

D. sewage discharged from sewage treatment plants.

E. When the water sample to be analyzed is industrial wastewater containing refractory substances, it is taken from water about 3-8km downstream of the water discharge port to be analyzed or water containing microorganisms suitable for the water to be analyzed, and cultured in the laboratory.

2 hydrochloric acid solution

The following solutions can be stable for at least one month, and should be kept in glass bottles and kept away from light. Once signs of biological growth are found, they should be discarded.

2. 1 phosphate: buffer solution.

8.5g of potassium dihydrogen phosphate (KH2PO4), 2 1.75g of dipotassium hydrogen phosphate (K2HPO4), 33.4g of disodium hydrogen phosphate heptahydrate (Na2HPO4 7H2O) and 1.7g of ammonium chloride (NH4CI) were dissolved in about 500ml of water and diluted1.

The pH value of the buffer solution should be 7.2.

2.2 magnesium sulfate heptahydrate: 22.5g/L solution.

22.5g of magnesium sulfate heptahydrate (MgSO4 7H2O) was dissolved in water, diluted to 1000 ml, and mixed evenly.

2.3 Calcium chloride: 27.5g/L solution.

Dissolve 27.5g of anhydrous calcium chloride (CaCl2) (if calcium chloride hydrate is used, a considerable amount should be taken) in water, dilute it to 1000 ml, and mix it evenly.

2.4 ferric chloride (iii) hexahydrate: 0.25g/l solution.

0.25g ferric chloride (III) hexahydrate (FeCl 3 6H2O) was dissolved in water, diluted to 1000ml, and mixed evenly.

3 dilution water

Take each salt solution 1ml, add it to about 500ml of water, then dilute it to 1000m and mix well. Put this solution at 20℃ and ventilate it for more than 65,438+/-0h. Take various measures to prevent it from being polluted, especially by organic matter, oxidizing or reducing substances or metals, and ensure that the dissolved oxygen concentration is not lower than 8 mg/L. The biochemical oxygen demand of this solution shall not exceed 0.2 mg/L for five days. This solution should be used within 8 hours.

4 diluted inoculation water

According to the need and the source of inoculation water, add 1.0-5.0ml of inoculation water to each liter of dilution water, and store the diluted water after inoculation at about 20oC, and smear it as soon as possible after 8 hours. The oxygen consumption should be between 0.3- 1.0mg/l after inoculation with diluted water for 5 days (20oC).

5 hydrochloric acid solution: 0.5g/L.

6 NaOH solution: 20g/L.

7 Sodium sulfite solution: 1.575 g/L This solution is unstable and needs to be prepared every day.

8 glucose-glutamic acid standard solution.

Dry some anhydrous glucose (C6H 12O6) and some glutamic acid (hooc-CH2-CH2-chnh 2-cooh) at 103℃/0/h, and weigh 150 1mg respectively. The solution is prepared before use.

tool

The glassware used should be carefully cleaned, toxic or biodegradable compounds should not be absorbed, and pollution should be prevented. Commonly used laboratory equipment is as follows:

1 culture bottle: the capacity of narrow-mouth bottle is between 250 and 300ml, with frosted glass stopper and bell mouth for water supply sealing, preferably with straight shoulder.

Incubator: it can be controlled at 20 1oC.

Instrument for measuring dissolved oxygen.

4 Refrigeration device (0-4℃) for sample transportation and storage.

Dilution container: glass bottle with stopper, the scale is accurate to milliliter, and its volume depends on the volume of diluted water sample.

Storage of samples

Samples should be packed and sealed in bottles and stored at 2-5℃ before analysis. In general, the inspection shall be carried out within 6 hours after sampling. In case of long-distance transshipment, the storage time shall not exceed 24 hours under any circumstances. Samples can also be stored in refrigeration.

operation sequence/order

1 Pretreatment of samples

1. 1 Neutralization of samples

If the PH value of the sample is not between 6 and 8, a separate test is conducted to determine the volume of hydrochloric acid solution or sodium hydroxide solution to be used, and then the sample is verified, regardless of whether precipitation is formed.

1.2 samples containing free chlorine or bound chlorine

Add the required volume of sodium sulfite solution to make the free chlorine and combined chlorine in the sample invalid, and pay attention to avoid excessive.

2 Preparation of test water sample

Raise the temperature of the test sample to about 20oC, and then shake the sample in a half-full container to eliminate possible supersaturated oxygen.

Place the sample with a known volume in a dilution container, dilute it with dilution water or inoculation dilution water, and gently stir it to avoid bubbles.

Steps of gas cylinder pressure detection For those with deflation or indicator plug, connect the plug, start the car, see the measurable peak explosion pressure, or make indicator diagram.

Measure the compression pressure of seal inspection; Turn the car at idle speed after the fuel is cut off, and see the peak.

There is no syringe hole available for Cork.

Contact the manufacturer and ask if there are any special tools.

Methods and Steps of Water Leakage Detection Baoding Jinma Water Leakage Detection Co., Ltd. is located in Baoding National High-tech Industrial Development Zone, and is a professional company engaged in pipeline water leakage detection, pipe network detection and data processing, water balance test, thermal efficiency test and pipeline engineering technical services.

Jinma Company has a group of experienced and dedicated professional technicians who have been engaged in pipeline nondestructive testing and pipeline testing for many years, which is the core strength of the company's development.

Introduction of water leakage detection steps

1, collect pipeline data

Collect the drawings and water consumption data of the pipeline to be tested, and the enterprise will arrange technicians familiar with the pipeline position to point out the plane position, buried depth, material, pipe diameter and other related information on the spot.

2. Environmental investigation of regional pipe network

The purpose of pipe network environmental investigation is to fully understand the site situation and prepare for the construction arrangement and method selection of the next leak detection work, including pipe network environmental investigation, auxiliary equipment investigation, water use investigation and drainage investigation.

(1) Environmental investigation of pipe network: ① water supply pressure; (2) pipes; ③ Pipeline laying.

(2) Fitting investigation: investigate the wells, meters, valves and bolts in the area, and make a preliminary investigation on the water leakage of the above fittings.

(3) Drainage investigation: Investigate all underground structures involved in detail, such as drainage pipes and cables near pipe networks.

3. Detailed investigation of water leakage

In the work area, the fire hydrants, valves, water meters and exposed pipes in the area 100% are directly monitored during the day to monitor the sound waves propagating from the water leakage point to the pipeline structures, and abnormal water leakage is found. After finding any abnormality, make detailed records, including field number, location, abnormal nature, abnormal situation and explanation.

(1) Hearing test

● Above the pipeline in the survey area, listen to the sound along the pipeline along the "S" route with an interval of 0.5 ~1.0m. ..

● The operation should be carried out in the period when the water consumption is relatively stable and the surrounding environment is relatively quiet.

● Investigate the water leakage of pipelines buried under the road surface, and mark the possible water leakage places on the ground.

A. detect the "m" contour at the abnormal position.

B. The road hearing rate is 100%, and the abnormal sound detection rate is 100%.

C. record the abnormal points and surrounding environment in detail.

D road monitoring should also assist valve plug monitoring and environmental investigation.

(2) Confirmation and location of water leakage point.

For the abnormal water leakage or area that has been found, organize personnel with high technical level and rich experience to make abnormal judgment, eliminate abnormal interference and confirm whether it belongs to abnormal water leakage. If the water leakage is abnormal, the water leakage point will be accurately located.

Accurate location of water leakage point is a comprehensive and complicated work. It is necessary to comprehensively use various methods such as ground sound intensity and audio detection, pipeline sound intensity and short-range sound intensity audio detection, and comprehensively analyze the results of various detection methods such as valve plug detection, road surface detection and related detection, and finally confirm the accurate location of the water leakage point.

③ Technical methods of water leakage detection.

Water leakage detection technology is a comprehensive technology. Water leakage detection methods mainly include passive detection, flow detection, pressure analysis, acoustic detection, audio-visual detection, related instrument detection, tracer gas detection, CCTV pipeline endoscopic detection, far-infrared thermal imaging detection and so on. Each method has its own advantages and disadvantages and scope of application.

④ Correlator detection.

Hearing stick

Directly listen to the water leakage sound of pipeline ancillary facilities, assist other water leakage detection instruments, and accurately locate the water leakage point. The technicians needed are very experienced.

La-60 water leakage detector

La-60 water leakage detector faithfully reproduces the water leakage sound by using the front sound compensator, which is not affected by the surrounding noise and vibration. Whether there is water leakage or not, the obtained data can be converted into interpretable data through the comprehensive performance of frequency analysis; There is a lighting device in the instrument, which can easily distinguish the indicators when working at night; The sensor is sensitive and practical, and the signal reception is not affected by the ground conditions.

Fuji audio-visual professional water leakage detector has high sensitivity ground pickup and specially designed ball, which can effectively reduce the interference noise of wind; The pickup is light in design, which minimizes the labor intensity of field operators; The large indicator clearly shows the strength of the leaked audio signal; Keys and knobs diagonally arranged on the panel.

RD3 12 Metal Detector

RD3 12 metal detector is a simple and portable metal detector, which can detect buried metal manhole covers, valve boxes, valve covers, etc. It has the function of automatic gain adjustment to further enhance the detection effect, and can also be used in shallow water.

The working principle of correlator: two sensors are placed on the pipeline suspected of leaking water, and the sound from the leaking point will spread to the left and right sides at a certain speed (V), and the propagation speed (V) is determined by the pipe material and pipe diameter. Record the time difference (Td) when the leaking sound reaches the two sensors. Knowing the material and length of the pipeline, the correlator can accurately calculate the location of the leaking point.

Calculation formula of correlation principle:

Related test technical requirements

● For correlation analysis, two acceleration sensors must be placed on the same pipeline.

● Reasonable detection distance should be selected according to site conditions.

● Relevant measurement must find out the direction and connection of the target pipeline.

⑤ Closed-circuit television endoscope detection

The closed-circuit television inspection of the pipeline adopts the advanced closed-circuit television pipeline endoscope television inspection system, and the robot automatically crawls in the pipeline to detect and photograph the rust layer, scaling, corrosion, perforation and cracks in the pipeline, so that the image data of the pipeline inner wall can be seen at a glance.

Characteristics of closed-circuit television endoscope detection

The image is clear, light and compact, easy to operate and practical.

● The camera height can be adjusted freely, and the lens can rotate freely at 360 degrees+120 degrees.

● You can use * * equipment to measure the length of the pipeline and determine the damage of the pipeline.

● You can insert words such as time length on the screen to ensure the complete record of data.

● You can enter the necessary information on the screen and burn it to a CD.

Tracer gas detection method

1. Pipeline sealing gas source. After the completion of the inflation test, for the pipeline with abnormal pressure and confirmed leakage, a mixture of hydrogen and nitrogen (a safe mixture of 5% hydrogen and 95% nitrogen) should be injected into the pipeline, which should generally reach 2kg/cm2.

2. Above the pipeline, the bell probe of hydrogen detector is used for sampling measurement at intervals of 0.5~0.8m along the pipeline direction. Each time lasts about 20-30 seconds, and the abnormal points and their surroundings are recorded in detail; The detection work is to detect whether the pipeline buried under the road surface leaks from the road surface, so the possible leakage points are marked on the ground. Further inspection work to find out the exact location of the leak.

● Safe, non-toxic and non-combustible, and safe to use.

Hydrogen is the lightest gas.

Hydrogen permeability is very low.

The detection accuracy is low, and the detection concentration is 65438±0 ppm.

Characteristics of tracer gas detection:

● Mixed gas of 5% hydrogen and 95% nitrogen.

⑥ Tracer gas detector

● Simple operation with menu guidance function.

● Small leakage points of water pipes and gas pipelines can be located.

● Powerful instrument box and night lighting function.

When hydrogen tracer method is used, absorbing the air in the surrounding environment will not dilute the leaked gas.

The sensor is directly connected with the bell probe, which can quickly display the dispersed gas molecules.

The low hydrogen tracer method can quickly determine the leakage point, and the detectable concentration is 65438±0 ppm.

⑦ infrared thermal imaging detection principle

Infrared thermal imaging detection is to use photoelectric technology to detect the infrared specific band signal of thermal radiation of objects, convert the signal into images and graphics that can be distinguished by human vision, and further calculate the temperature value. Infrared thermal imaging technology enables human beings to transcend visual obstacles and make judgments according to the temperature distribution on the surface of objects.

4, water leakage detection has been done three no matter:

Regardless of the diameter, the diameter from DN 15 to DN2000 can be detected as long as there is leakage.

No matter what the material of the pipeline is, whether it is steel pipe, cast iron pipe, cement pipe or even ceramic pipe, as long as there is leakage, the leakage point can be detected.

No matter what the circulating medium in the pipeline is, whether it is water pipeline, oil pipeline or gas pipeline, as long as there is leakage, the leakage point can be detected.

Please explain the composition and principle of intrusion detection? What is asynchronous detection? Intrusion detection technology (IDS) can be defined as a system to identify and deal with malicious use of computer and network resources. Including the intrusion from outside the system and the unauthorized behavior of internal users, is a technology designed and configured to ensure the security of computer systems, which can find and report unauthorized or abnormal phenomena in the system in time, and is also a technology used to detect the violation of security policies in computer networks.

There are many intrusion detection methods, such as expert system-based intrusion detection method and neural network-based intrusion detection method. At present, some intrusion detection systems have realized application-level intrusion detection.

Intrusion detection is achieved by performing the following tasks:

1. Monitor and analyze user and system activities;

2. Audit of system structure and weakness;

3. Identify activity patterns that reflect known attacks and alert relevant personnel;

4. Statistical analysis of abnormal behavior patterns;

5. Evaluate the integrity of important systems and data files;

6. Audit the tracking management of the operating system and identify users' behaviors that violate security policies.

Typical representative of intrusion detection system

The typical representative of intrusion detection system is RealSecure of ISS (Internet Security System Company). It is an automatic real-time intrusion detection and response system on the computer network. It can monitor network transmission without obstacles, automatically detect and respond to suspicious behaviors, and capture and respond to security vulnerabilities and internal misuse before the system is compromised, thus providing security for enterprise networks to the greatest extent.

Problems existing in current intrusion detection system:

1. The detection speed of the existing intrusion detection system is far behind the network transmission speed, resulting in false positive rate and false negative rate.

2. The combination of intrusion detection products and other network security products, that is, information exchange during the period, * * * cooperation to find attacks and block attacks.

3. The network-based intrusion detection system can't detect the encrypted data stream and the data stream under the switching network, and its own structure is vulnerable to attack.

4. The architecture of intrusion detection system.

Development trend:

1. The combination of distributed collaborative intrusion detection based on agent and general intrusion detection.

2. At present, there is no unified standard for the research of intrusion detection standards.

3. Real-time intrusion detection technology of broadband high-speed network.

4. Intelligent intrusion detection

5. Intrusion detection measures