Product Characteristics of Vacuum Oven

The vacuum oven can obtain a higher drying rate at a lower temperature, and the heat utilization is full, which is mainly suitable for the drying of heat-sensitive materials and materials containing capacitors and solvents to be recovered. It can be treated before drying, and no debris can be mixed in the drying process. The dryer is a static vacuum dryer, so the formation of dry materials will not be damaged. There are many eating methods: steam, hot water, thermal oil and electric heating.

Vacuum ovens are designed for drying heat-sensitive, easily decomposed and easily oxidized substances, and can be filled with inert gases, especially for some complex items.

The product has the following features:

1, chamber structure:  chamber adopts integral structure;

2, shell material: high-quality cold-rolled steel electrostatic spray; Inner wall material: stainless steel plate;

3, insulation material: ultrafine glass fiber;

4, the door seal: environmental protection silicone rubber strip. The closure and tightness of the box can be adjusted, and the silicone rubber door sealing ring is formed as a whole to ensure a high vacuum inside the box.

5, the studio is made of stainless steel plate (or wire drawing plate) to ensure that the product is durable.

6, storage, heating, testing and drying are carried out in an environment without oxygen or full of inert gases, so there is no oxidation.

7, the shortest heating time, compared with the traditional drying oven heating time reduced by more than 50%. Because the vacuum oven is provided with heat energy by electricity, and the wet items are conductive, it is advisable to be careful not to have leakage in use, so the general oven should be grounded to ensure safety. If there is no ground wire, it is necessary to confirm that there is no leakage of electricity in the oven; If there is no leakage, it can be used with care, and if there is still leakage, it should be stopped immediately.

Vacuum oven is designed for drying heat-sensitive, easily decomposed and easily oxidized substances, can be filled with inert gas (optional), especially some complex components of the articles can also be fast drying, suitable for industrial and mining enterprises, medical schools, scientific research units in vacuum conditions for drying heat treatment.

Reliability Testing Acceleration Testing

Most semiconductor devices have lifetimes that extend over many years at normal use. However, we cannot wait years to study a device; we have to increase the applied stress. Applied stresses enhance or accelerate potential fail mechanisms, help identify the root cause, and help labcompanion take actions to prevent the failure mode.

In semiconductor devices, some common accelerants are temperature, humidity, voltage, and current. In most cases, the accelerated testing does not change the physics of the failure, but it does shift the time for observation. The shift between accelerated and use condition is known as ‘derating.’

Highly accelerated testing is a key part of JEDEC based qualification tests. The tests below reflect highly accelerated conditions based on JEDEC spec JESD47. If the product passes these tests, the devices are acceptable for most use cases.

Temperature Cycle

Per the JESD22-A104 standard, temperature cycling (TC) subjects the units to extreme high and low temperatures transitions between the two. The test is performed by cycling the unit's exposure to these conditions for a predetermined number of cycles.

High Temperature Operating Life (HTOL)

HTOL is used to determine the reliability of a device at high temperature while under operating conditions. The test is usually run over an extended period of time according to the JESD22-A108 standard.

Temperature Humidity Bias/Biased Highly Accelerated Stress Test (BHAST)

According to the JESD22-A110 standard, THB and BHAST subject a device to high temperature and high humidity conditions while under a voltage bias with the goal of accelerating corrosion within the device. THB and BHAST serve the same purpose, but BHAST conditions and testing procedures enable the reliability team to test much faster than THB.

Autoclave/Unbiased HAST

Autoclave and Unbiased HAST determine the reliability of a device under high temperature and high humidity conditions. Like THB and BHAST, it is performed to accelerate corrosion. Unlike those tests, however, the units are not stressed under a bias.

High Temperature Storage

HTS (also called Bake or HTSL) serves to determine long-term reliability of a device under high temperatures. Unlike HTOL, the device is not under operating conditions for the duration of the test.

Electrostatic Discharge (ESD)

Static charge is an unbalanced electrical charge at rest. Typically, it is created by insulator surfaces rubbing together or pulling apart; one surface gains electrons, while the other surface loses electrons. The result is an unbalanced electrical condition known as static charge.

When a static charge moves from one surface to another, it becomes Electrostatic Discharge (ESD) and moves between the two surfaces in a form of a miniature lightning bolt.

When a static charge moves, it becomes a current that can damage or destroy gate oxide, metal layers, and junctions.

JEDEC tests ESD in two different ways:

1. Human Body Mode (HBM)

A component level stress developed to simulate the action of a human body discharging accumulated static charge through a device to ground.

2. Charged Device Model (CDM)

A component level stress that simulates charging and discharging events that occur in production equipment and processes, per the JEDEC JESD22-C101 specification.

Smart Watch Reliability Test Conditions

In today's society, elementary school students and even kindergarten children have a smart watch. So, what is a smartwatch? In the late period of sports watch promotion due to the rapid takeoff of smart phones, the smart table has no intention to provide the same PIM effect as PDA and smart phones, and appeals to the smart phone agent assistant accessories, similar to Bluetooth headphones are voice AIDS of smart phones, smart tables become information and data AIDS, providing more convenient and fast information display and operation. There are also other names such as Smart Accessory and Android Remote. Positioned as a mobile phone assistant, the idea is that "the reason why the pocket watch is extinct is because it is simply to look at the time, but also take out the pocket, about 2-3 seconds, but the watch is less than 1 second, which is more convenient than the pocket watch." And after observation, now everyone takes out a smartphone and slides open, just to confirm the message, so that about dozens of times, these confirmation even typing reply do not need, if the dozens of confirmation changed on the watch, you do not always have to pull the machine slide unlock, because this is as time-consuming as a pocket watch. Therefore, after becoming the assistant of the mobile phone, the remote control, if you do not take the mobile phone to go out, the watch is useless in addition to showing the time, and the Bluetooth headset without a mobile phone, almost scrap metal.

Combined with smart bracelet to sell better!!

Smart watch from "smaller than the PDA independent computer" to "smart phone remote control AIDS", seems to have been a more successful positioning, but this CES 2014 can be seen, combined with smart bracelet positioning is better. The smart wristband uses acceleration sensors (and gyroscopes, magnetoresistive sensors, etc.) to sense the user's running speed, step count, etc., and can even detect deep sleep and provide suggestions for exercise and sleep. When the wristband is added to the display, it can display the time and information on the mobile phone. Appeal to mobile phone information, if there is no urgent information needs, in fact, only similar to the Bluetooth headset is regarded as an option (Courier, driver need), if everyone can accept the information access speed of sliding, then the market will be limited. However, in addition to the appeal for exercise and sleep record supervision, and emphasize information tips, rather than emphasizing the remote control of the watch on the mobile phone, it is equivalent to a little sacrifice or almost no sacrifice to the end user, but it brings immediate and new application value (sports, sleep assistance), rather than completely repeating the efficacy value of the mobile phone, which further increases the market success of the smart watch. After constantly adjusting the efficacy, application and positioning, and integrating with the smart ring, we believe that we can have a higher market than in the past.

Smart watch for people and functions:

1. Smart watches for adults

Functions: Bluetooth synchronous mobile phone calls, send and receive text messages, monitor sleep, monitor heart rate, sedentary reminder, running, remote photography, music playback, video, compass and other functions, designed for fashion trend people!

2, Smart watch for the elderly

Functions: ultra-accurate GPS positioning, family calls, emergency calls, heart rate monitoring, sedentary reminders, medicine reminders and other customized functions for the elderly, providing an umbrella for the elderly's travel, bring this watch, refuse to lose the elderly!

3, Children positioning smart watch

Functions: multiple positioning, two-way call, SOS SOS, remote monitoring, intelligent anti-loss, historical track, electronic fence, pedometer, love reward and other functions, to ensure the safety of children, give children a healthy and safe growth environment!

Smart watch specification:

IEC 60086-3: Watch batteries

ISO 105-A02: Colour fastness test -A02 - Grey scale assessment for discoloration

ISO 105-A03-1993: Tests for colour fastness -A03- Grey scale assessment of dyeing

ISO 764: Horological anti-magnetic watches

ISO 1413: Horological shockproof watches

ISO 2281: Horological waterproof watches

ISO 11641-1993: Leather - tests for colour fastness - Colour fastness to perspiration

ISO 14368-3: Impact resistance test of table glass

MIL 810G: Environmental engineering considerations and laboratory testing

QB/T 1897-1993: Waterproof watch inspection

QB/T 1898-1993: Inspection of shockproof watches

QB/T 1908-1993: Key reliability test

QB/T 1919-2012: Type inspection of digital quartz watches with hands and liquid crystal

QB/T 2047-2007: Inspection of metal watchbands

GB/T 2537-2001: leather color fastness test reciprocating grinding color fastness

QB/T 2540-2002: Leather strap inspection

GB/T 6048-1985: digital quartz electronic watch

GB/T 18761-2007: electronic digital display indicator

GB/T 18828-2002: Standard for diving watches

GB/T 22778-2008: LCD digital quartz stopwatch type inspection

GB/T 22780-2008: Type inspection of LCD quartz watches

GB/T 26716-2011 idt ISO 764-2002: Inspection of anti-magnetic watches

HJ216-2005: Eco-Drive watch

Smart watch pilot project:

Reliability, time period measurement accuracy, instantaneous daily difference, operating temperature, voltage range, average temperature coefficient, voltage coefficient, moisture resistance, shock resistance, waterproof performance, battery replacement cycle, key fatigue resistance, light and weather resistance, antistatic performance Ambient temperature range: -25℃ ~ 55℃ Operating temperature: -5 ~ 50℃/80%R.H.(Requirements: each function and liquid crystal display should be complete and normal) High and low working temperature test: 50±1℃/24h→RT/1h→-5±1℃ Temperature change test conditions: (IEC60068-2) High temperature: 30, 40, 55℃ Low temperature: 5, -5, -10, -25℃ Nb residence time (including rising and cooling time) : 10min, 30min, 1hr Nb temperature variability: 3±0.6℃/min, 5±1℃/min.

Wet heat test:

1.40±1℃/85 ~ 95%R.H./24h

2.8±1℃/85 ~ 95%R.H./4h

Warehouse storage humidity test:

40℃/20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%

49℃/10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%

Each step37 hours

Air transport temperature change simulation test:

Specification: IEC60721.2 Electrical and electronic products application environmental conditions - transport national standard

Category: 2K5 (Applicable to the climatic range of unventilated and unpressurized internal transport worldwide)

Temperature range: -65℃←→85℃

RAMP: 5℃/min

Air transport temperature change simulation test:

Specification: IEC60721.6 Electrical and electronic products application environmental conditions - Marine

Category: 6K5 (subject to cold weather, installed in weather-protected but unheated parts)

Temperature range: -25℃←→40℃

RAMP: 3℃/min

Water temperature change resistance test:

5min in 40℃ water → 5min in 20℃ water, 5min in 40℃ water, water depth of 10cm

Water pressure resistance test:

Soak the watch in a container of water, apply an overpressure of 2*10^5Pa[or 20m water depth] within 1 minute, maintain 10 minutes, and then in 1 minute the pressure will be to the standard pressure of the surrounding environment

Salt water resistance test:

Put the watch under test into 30g/L sodium chloride solution at 18 ° C ~ 25 ° C for 24h. Check the case and accessories after the test should not have significant changes; Check the moving parts, especially the rotating front ring should be able to maintain normal function

Underwater reliability test:

The watch under test is immersed in 30cm±2cm of water and placed at a temperature of 18 ° C ~ 25 ° C for 50h, and all mechanical devices should still work normally. During the test, mechanical devices that need to be operated in water, such as time presetting devices and light switches, should be able to work normally; Do condensation test, the inner surface of the table glass shall not appear condensation fog, and the mechanical function should not be damaged

Thermal shock resistance test:

Immerse the watch in water of different temperatures with a depth of 30cm±2cm successively: place it in water of 40 ° C ±2 ° C for 10 minutes; Put in 5℃±2℃ water for 10 minutes; Put in water at 40 ° C ± 2 ° C for 10 minutes (the watch shall not be removed from the water and re-immersed in another water temperature for more than 1 minute). Do condensation test, the inner surface of the table glass shall not appear condensation fog, and should operate normally.

Chemical resistance test:

Citation Specifications: ASTM F 1598-95, ASTM D 1308-87, ASTM D 1308-02

Ingredients: Household chemicals (dirt, dust, oil, fumes and peanut butter, cosmetics, hand cream... Etc.)

Time: 24 hours

Corrosion resistance to artificial sweat test:

QB/T 1901.2-2006 "Gold alloy covers of shell and its accessories - Part 2 Test for purity, thickness, corrosion resistance and adhesion"

Test principle: The artificial sweat is used to contact the object under high temperature (40±2) ℃, and after a long time (not less than 24 hours), the condition of its surface is observed to determine its resistance to sweat corrosion.

Vibration test:

Acceleration (19.6m/s^2), frequency 30Hz ~ 120Hz, scanning cycle 1min

Requirements: The functions and the LCD display should be complete and normal, and the parts should not be loose and fall off

Drop test:

1m drop lithographic hardwood, once watch side, once surface glass

Requirements: Normal function after each impact, no appearance damage [broken glass, case foot bent, case component bent, case broken, button damaged]

Impact test:

Impact cone pad material: polytetrafluoroethylene, impact speed 4.43m/s, impact height 1m

Arm swing test:

2 to 10Hz

Solar Module Test

Solar energy is a kind of renewable energy, refers to the sun's thermal radiation energy, the main performance is often said that the sun rays, in the modern generally used for power generation or to provide energy for water heaters. In the case of decreasing fossil fuels, solar energy has become an important part of human energy use and continues to develop. The use of solar energy has two ways of photothermal conversion, solar power generation is an emerging renewable energy, so the related solar energy research and application industry has also stepped up the pace of development. In the research and production process of the solar module, the relevant reliability test and environmental test specifications have been formulated to ensure that the solar module can be durable for more than 20 to 30 years and its power generation conversion rate when used in outdoor environment.

Solar module HAST and PCT test illustration

Temperature and humidity test IEC61215-10-13:

Temperature and humidity test  conditions are 85℃/85%R.H., time: 1000 hours, to determine the ability of the module to resist long-term moisture penetration, through the temperature and humidity test  can be found defects: CELL delamination, EVA(delamination, discoloration, bubble generation, atomization, Browning), string line blackening, TCO corrosion, solder joint corrosion, Thin-film yellow discoloration, junction box degumming off... However, according to the test results of relevant Solar plants,1000 hours is not enough, and the actual situation finds that the test time to enable the module to find the problem needs to be at least 3000 to 5000 hours.

Test method of HAST [Highly Accelerated Temperature and Humidity Stress Test]:

HAST is short for Highly Accelerated Temperature and Humidity Stress Test in English. The highly accelerated humidity resistance evaluation test method is based on the environmental parameters of temperature and humidity. HAST and PCT [Pressure Cooker Test] are different from the two tests, HAST is called unsaturated test, while PCT is saturated humidity test, and the biggest difference from the general humidity evaluation test method is that it is in the field of temperature and humidity above 100℃, and is in the high-density water vapor environment test. The purpose of HAST is to accelerate the test of humidity intrusion into the sample for humidity resistance evaluation by taking advantage of the fact that the water vapor pressure in the test tank is much higher than the water vapor partial pressure inside the sample.

Test specifications and conditions of JESD22-A118[Accelerated Moisture Resistance-Unbiased](HAST unbiased test) :

It is used to evaluate the reliability of the device in wet environment, that is, the penetration of harsh temperature, humidity and increased water vapor pressure through the external protective material (encapsulation or sealing material) or along the interface of the external protective material and metal conductor, the failure mechanism is the same as that of the [85℃/85%RH] high temperature and high humidity steady-state humidity life test (JESD22-A101-B). In this test process, no bias is applied to ensure that the failure mechanism is not covered by bias, and this test is used to determine the failure mechanism in the package. The sample is in a non-condense humidity environment, only the temperature is increased a little, and the failure mechanism is the same as the [85℃/85%RH] high temperature and high humidity steady-state humidity life test without bias. It should be noted that, Since absorbed water vapor reduces the glass transition temperature of most polymer materials, an unreal failure mode may occur when the temperature is higher than the glass transition temperature.

85℃/85%/1000H(JESD22-A101)→110 ℃/85%/264H(JESD22-A110, A118)

Specifications: JEDEC22-A110(with bias), JEDEC22-A118(without bias)

Common conditions: 110℃/85%R.H./264h Applicable: PET, EVA, modules

Test method of PCT [Pressure Cooker Test]:

Generally known as the pressure cooker cooking test or saturated steam test, the most important is to test the product under harsh temperature, saturated humidity (100%R.H.)[saturated water vapor] and pressure environment, test the high humidity resistance of the test product, for solar packaging materials or modules, used for material moisture absorption test, high pressure cooking... For the purpose of the test, if the product to be tested is a Cell, it is used to test the moisture resistance of the Cell. The product to be tested is placed in a harsh temperature, humidity and pressure environment for testing. If the package is not well packaged, moisture will penetrate into the package along the colloid or the interface between the colloid and the wire frame. Popcorn effect, open circuit caused by metal wire corrosion, short circuit caused by contamination between package pins... And other related issues, and HAST accelerated aging is not the same.

Test specifications and conditions of PCT JESD22-A102:

To evaluate the integrity of non-airtight packaged devices against water vapor in a condensed or saturated water vapor environment, the sample is placed in a condensed, high-humidity environment under high pressure to allow water vapor to enter the package, exposing weaknesses in the package, such as delamination and metallization layer corrosion. The test is used to evaluate the new package structure or the update of the material and design in the package body. It should be noted that some internal or external failure mechanisms will appear in the test which are not consistent with the actual application situation. Since absorbed water vapor reduces the glass transition temperature of most polymer materials, an unreal failure mode may occur when the temperature is higher than the glass transition temperature.

Test conditions: 121℃/100%R.H./80h(COVEME), 200h[toyalSolar]

Applicable: PET, EVA, modules

Pressure cookers (PCTS) and Highly Accelerated Life Test Equipment (HAST) :

At present, most solar materials and modules can withstand long-term DHB(temperature and humidity + bias) test without failure, in order to improve the test efficiency and shorten the test time, the pressure cooker test method is used. Pressure cooker test methods are mainly divided into two types: That is, PCT and HAST, if the defects of solar packaging materials and modules can be found through HAST tests, and the degradation can be reduced by 1%, the LCOE[Levelized Cost of Electricity(actual energy output value, power generation cost per KWH)] will be reduced by 10%. The purpose of the PCT test is to increase the ambient stress (temperature & humidity), and to evaluate the sealing effect of the module and the moisture absorption of the backplane by exposing it to a wetting vapor pressure of more than one atmosphere.

The Relationship Between the Altitude of the Standard Atmosphere and Air Temperature and Pressure

The standard atmosphere referred to here refers to the "1964, ICAO Standard atmosphere" adopted by the International Civil Aviation Organization. Below an altitude of 32 km, it is the same as "1976, U.S. standard atmosphere". Changes in air temperature near the surface (below 32 km) are:

Ground: The air temperature is 15.0℃, the air pressure P=1013.25mb= 0.101325MPa

Temperature change rate from ground to elevation 11 km: -6.5 ℃/ km

On the 11km interface:

The air temperature is -56.5 ℃ and the air pressure P=226.32mb

Temperature change rate at elevations of 11-20 km: 0.0℃/ km

Temperature change rate at altitude 20-32 km: +1.0/ km

The following table lists the temperature and pressure values of the standard atmosphere at different altitudes. In the table, "gpm" is the altitude meter, and its negative sign represents the altitude

Unit conversion relation

1mbar=100Pa=0.1KPa=0.0001 Mpa

1ft=0.3048m=304.8mm

55000ft*0.3048=16764m

Lab Companion focused on the production of reliability environmental test equipment for 19 years, successfully helped 18,000 enterprises to test the reliability and environmental performance of products and materials.

The main products are: high temperature test chamber, high and low temperature and humidity test chamber, walk-in environmental test chamber, rapid temperature cycling test chamber, thermal shock test chamber, high and low temperature low pressure test chamber, vibration of the comprehensive chamber and other test equipment manufacturing solutions to help enterprises R & D bigger and stronger!

If you need to know more about the products of the environmental test chamber, you can search the official website of "Lab Companion", feel free to contact us for consultation, we can provide you with one-on-one professional technical advice and guidance.

Thin Film Solar Cell

Thin film solar cell is a kind of solar cell manufactured by thin film technology, which has the advantages of low cost, thin thickness, light weight, flexibility and bendability. It is usually made of semiconductor materials such as copper indium gallium selenide (CIGS), cadmium telluride (CdTe), amorphous silicon, gallium arsenide (GaAs), etc. These materials have high photoelectric conversion efficiency and can generate electricity under low light conditions.

Thin film solar cells can be used in inexpensive glass, plastic, ceramics, graphite, metal sheet and other different materials as substrates to manufacture, forming a film thickness that can generate voltage only a few μm, so the amount of raw materials can be significantly reduced than silicon wafer solar cells under the same light receiving area (thickness can be lower than silicon wafer solar cells more than 90%). At present, the conversion efficiency of up to 13%, thin film solar cells are not only suitable for flat structure, because of its flexibility can also be made into non-plane structure, has a wide range of application prospects, can be combined with buildings or become a part of the building body.

Application of thin film solar cell product:

Translucent solar cell modules: Building Integrated Solar Energy Applications (BIPV)

Application of thin film solar energy: portable folding rechargeable power supply, military, travel

Applications of thin film solar modules: roofing, building integration, remote power supply, defense

Features of thin film solar cells:

1. Less power loss under the same shielding area (good power generation under weak light)

2. The loss of power under the same illumination is less than that of wafer solar cells

3. Better power temperature coefficient

4. Better light transmission

5. High cumulative power generation

6. Only a small amount of silicon is needed

7. There is no internal circuit short circuit problem (the connection has been built in the series battery manufacturing)

8. Thinner than wafer solar cells

9. Material supply is secure

10. Integrated use with building materials (BIPV)

Solar cell thickness comparison:

Crystalline silicon (200 ~ 350μm), amorphous film (0.5μm)

Types of thin film solar cells:

Amorphus Silicon (a-Si), Nanocrystalline Silicon (nc-Si), Microcrystalline Silicon, mc-Si), compound semiconductors II-IV [CdS, CdTe(cadmium telluride), CuInSe2], Dye Sensitized Solar cells, Organic/polymer solar cells, CIGS (Copper indium selenide)... Etc.

Thin-film solar module structure diagram:

Thin film solar module is composed of glass substrate, metal layer, transparent conductive layer, electrical function box, adhesive material, semiconductor layer... And so on.

Reliability test specification for thin film solar cells:

IEC61646(Thin-film solar photoelectric module test standard), CNS15115(thin-film silicon onshore solar photoelectric module design validation and type approval)

Temperature & humidity test chamber of Lab Companion

Temperature & humidity test chamber series, passed the CE certification, offer 34L, 64L, 100L, 180L, 340L, 600L, 1000L, 1500L and other volume models to meet the needs of different customers. In design, they use environment-friendly refrigerant and high-performance refrigeration system, parts and components are used in the international famous brand.

The following is the first part of the daily operation and maintenance of slurry pumps： tart-up and shutdown：

Preparations Before Start-up：

Check whether the connecting bolts and foundation bolts of the pump are loose.

Check whether the piping connection is proper and whether the centers of the pump and the driver are aligned. For pumps handling high-temperature or low-temperature liquids, the expansion and contraction of the piping may cause shaft misalignment, seizure, etc. Therefore, flexible pipe joints, etc., should be used.

Direct coupling and alignment. For small-sized pumps handling normal-temperature liquids, there is no problem in aligning the pump and the motor when the pump is stopped. However, for large-sized pumps handling high-temperature liquids, there is a large difference in the shaft center during operation and stoppage. To achieve correct alignment, generally heat to the operating temperature or stop the pump after the operation and quickly re-align to ensure that the shaft centers of both rotating parts are the same and avoid vibration and pump seizure.

Clean the piping. Before operation, the piping must be cleaned first to remove foreign objects, welding slag, etc. from the piping. Do not let foreign objects or welding slag fall into the pump body. Install pressure gauges before and after the strainer in the suction pipe to monitor the clogging of the strainer during operation.

Barring. Remove the coupling before start-up, turn the rotor by hand to observe whether there are any abnormal phenomena, and conduct a separate test run of the motor to check whether its rotation direction is the same as that of the pump. By rotating the coupling by hand, it can be found whether there are foreign objects between the impeller and the casing inside the pump. The barring should be even in weight, and there should be no abnormal noise inside the pump.

Start the oil pump and check whether the bearing lubrication is good.

Priming the pump. Fill the pump chamber with liquid before start-up to discharge air, liquefied gas, and steam from the suction pipe and the pump body.

Start-up：

The idle operation must be avoided. At the same time, open the suction valve, and close the discharge valve and each discharge hole.

Open the cooling water supply valve for the bearings.

If the stuffing box has a water jacket, open the cooling water supply valve of the stuffing box.

If the pump handling high-temperature liquid has not reached the working temperature, open the preheating valve, and close this valve after the pump is preheated.

If the pump is equipped with a liquid-sealing device, open the valve of the liquid-sealing system.

If equipped with an overheating device, open the bypass valve of the self-circulation system.

Start the motor.

When the pump flow increases and overheating is no longer possible, close the valve of the self-circulation system.

If the pump must be started with the check valve closed and the outlet gate valve open, the start-up steps are basically the same as the above method, except that the outlet gate valve should be opened for a period of time before the motor is started.

Gradually open the discharge valve.

Shutdown：

Open the valve on the self-circulation system.

Close the discharge valve.

Stop the motor.

If it is necessary to maintain the working temperature of the pump, open the preheating valve.

Close the cooling water supply valves of the bearings and the stuffing box.

If liquid-sealing is not required during the shutdown, close the liquid-sealing valve.

If it is a special pump device requirement or when the pump is opened for inspection, close the suction valve, and open the vent hole and various discharge holes.

Usually, the start-up and shutdown steps specified for turbine-driven pumps are basically the same as those for motor-driven pumps. Turbines have discharge valves, various drain holes, and sealing devices, which must be opened or closed before and after operation. In addition, turbines generally require preheating before start-up. Some turbines in the system are required to be started at any time, so barring operation is required. Therefore, the operator should operate according to the relevant regulations on the start-up and shutdown steps of the turbine provided by the turbine manufacturer.

Maintenance During Shutdown For standby pumps at the chemical plant site, when the in-use pump fails, they should be able to be switched over in time and put into normal operation to ensure that the chemical production process is not interrupted. This requires the maintenance of the standby pumps to keep them in good condition during the standby and shutdown period. Especially for standby pumps with interlock and automatic switching, their inlet and outlet valves are open, and the pumps are filled with the medium to be transported. As long as the driver rotates, they can start working immediately.

For standby pumps during the shutdown period, the quality and quantity of the lubricant should be checked frequently. The pump body and the medium inside the pump that needs to be heated and insulated should be heated and insulated. To prevent the rotor from bending due to its own weight and to prevent the shaft from adhering to the bearings and causing start-up difficulties, the standby pumps should be barring regularly.

For pumps that have been shut down for a long time, open the plugs on the pump body to drain the liquid inside the pump to avoid damage to the pump body due to cold weather. If necessary, open the pump body, clean the internal parts, and apply anti-rust oil. For pumps that have been shut down for a long time, whether they are on-site or in the warehouse, they should be barring regularly.

For details of the first part, please refer to the next blog post.

Lubrication: During the operation of a slurry pump, the possible intrusion of the conveyed medium, water, and other substances into the oil tank may affect the pump's normal operation. Therefore, it is necessary to check the quality and oil level of the lubricant frequently. The quality of the lubricant can be observed with the naked eye and analyzed by regular sampling. The amount of lubricating oil can be seen from the oil level mark.

For a new pump, the oil should be changed once after one week of operation. For a pump with replaced bearings during overhaul, the oil should also be changed. Because foreign substances enter the oil during the running-in of the new bearings and shafts, the oil must be changed. Thereafter, the oil should be changed once every quarter. The lubricating grease and lubricating oil used for chemical pumps should meet quality requirements. Tables 2-8 and 2-9 show the commonly used lubricating grease and lubricating oil for slurry pumps.

Vibration: During the operation of the pump, due to reasons such as poor quality of spare parts and maintenance, improper operation, or pipeline vibration, vibration often occurs. If the vibration exceeds the allowable value, the pump should be shut down for maintenance to prevent damage to the machine. Table 2-10 shows the allowable range of vibration values for slurry pumps.

Bearing temperature rise: During the operation of the pump, if the bearing temperature rises rapidly and after the temperature rise stabilizes, the bearing temperature is too high, which indicates that there are problems in the manufacturing or installation quality of the bearing; or the quality, quantity, or lubrication method of the bearing lubricating oil (grease) does not meet the requirements. If not dealt with in time, the bearing is in danger of being burned out. The allowable temperature for slurry pump bearings is <65°C for sliding bearings; and <70°C for rolling bearings. This allowable value refers to the allowable range of bearing temperature after running for a period of time. For a newly replaced bearing, at the initial stage of operation, the bearing temperature will rise relatively high. After running for a period of time, the temperature will drop somewhat and stabilize at a certain value.

The operating performance of slurry pump: During the operation of the pump, if there is no change in the liquid source and the opening degree of the valves on the inlet and outlet pipelines remains unchanged, but the flow rate or inlet and outlet pressure changes, it indicates that there is a fault in the pump or pipeline. The cause should be quickly identified and eliminated in time, otherwise, adverse consequences will be caused.

The size of the system resistance can be achieved by adjusting the opening degree of the inlet and outlet valves of the pump. For a determined pump system, when the outlet valve is fully opened, the system resistance is the smallest, and the corresponding flow rate is the largest, the head is the smallest, and the power is the largest. When the outlet valve is completely closed, the system resistance reaches a maximum value. At this time, the flow rate is zero, the head is the largest (a finite value), and the power is the smallest.

From this, the following points can be summarized:

When starting a slurry pump, in order to avoid overloading the prime mover, the outlet valve should be closed first and then opened slowly after the pump is started. In this way, it can avoid the superposition of the large starting load of the prime mover and the high power required by the pump when the outlet valve is fully opened, which may cause overloading of the prime mover.

As long as the pump chamber is filled with liquid (to avoid dry friction of the sealing ring, shaft seal, etc.), the slurry pump is allowed to operate for a short time when the outlet valve is closed. Except for the rapid temperature rise of the limited liquid in the pump chamber under the action of the rotating impeller, which has some adverse effects on the pump, there is no adverse effect on the prime mover. At this time, the load on the prime mover is the lightest.

During operation, any set of flow rates and heads within the performance range of the slurry pump can be obtained by adjusting the opening degree of the outlet valve. However, when the pump operates at the design operating point, its efficiency is the highest; the farther away from the design operating point, the lower the efficiency.

Unit sound: The sounds emitted by the pump during operation are some normal and some abnormal. For abnormal sounds, find out the cause and eliminate it in time. The following are roughly the reasons for the abnormal sounds of the pump.

Reasons on the fluid side: For example, insufficient inlet flow of the slurry pump causes cavitation and emits noise; air accumulation in the pump outlet pipeline causes water hammer and emits an impact sound.

Reasons on the mechanical side: The bearing quality does not meet the requirements or is damaged; the clearance between the moving and stationary parts of the pump is inappropriate, causing friction; shaft bending causes internal friction; parts are damaged and fall off; foreign objects fall into the pump, etc.

For details of the first part, please refer to the previous blog post.

Chemical Industry:

Transporting corrosive liquids: It can be used to transport strong acids such as hydrochloric acid, sulfuric acid, and nitric acid, as well as strong alkali solutions like sodium hydroxide. In the production process of various chemical fertilizers, fluorides, etc. in chemical production, magnetic pumps are also often used to transport relevant media. At this time, chemical-resistant magnetic pumps are required.

Transporting flammable and explosive liquids: Such as gasoline, methanol, toluene, and other organic solvents. Magnetic pumps have no mechanical seal and will not generate friction sparks, which can ensure the safety of the transportation process and reduce the risk of fire and explosion accidents. At this time, organic solvent transfer magnetic pumps are needed.

Participating in chemical reactions: In some chemical reactions that require the cyclic transportation of reaction liquids, magnetic pumps can stably provide power to ensure the smooth progress of the reaction, for example, in the cyclic process of gas-absorbing reaction liquid. At this time, stainless steel chemical process magnetic pumps are needed.

Pharmaceutical Industry:

Liquid medicine transportation: It is used to transport various liquid medicines, slurries, biological drugs, etc. Its leak-free and pollution-free characteristics can ensure the purity and quality of drugs, and ensure the stability and safety of drugs, meeting the strict requirements of pharmaceutical production. At this time, sanitary magnetic drive centrifugal pumps are required.

Pharmaceutical equipment support: In some pharmaceutical equipment, such as washing machines, reactors, etc., magnetic pumps need to be used in conjunction with transport media to meet the fluid transportation requirements in the pharmaceutical process. At this time, stainless steel chemical process magnetic pumps are needed.

Food Industry:

 In the fields of food processing and beverage production, magnetic pumps can be used to transport food raw materials or finished products such as fruit juice, milk, and syrup. Since there are no leak-prone or liquid-contacting parts, it will not cause secondary pollution to food, can maintain the original taste and quality of food, and improve the food hygiene standard. At this time, sanitary magnetic drive centrifugal pumps are required.

Electronic Industry:

 It is mainly used to transport corrosive liquids, pure water, and other media. In the electronic production process, the purity and cleanliness of the media are required to be extremely high. Magnetic pumps have no seals, which can avoid liquid leakage and damage to electronic equipment, and can also meet the high requirements of the electronic industry for media. At this time, fluoroplastic anti-corrosion magnetic pumps are required.

Electroplating Industry: 

It is suitable for the transportation and cyclic filtration of various electroplating solutions, such as chrome-plating solutions, nickel-plating solutions, zinc-plating solutions, etc. Magnetic pumps can run stably in the harsh environment of the electroplating process, ensure the accurate transportation of electroplating solutions, and improve the efficiency and quality of electroplating production. At this time, polyvinylidene fluoride (PVDF) material magnetic-driven pumps are required.

Petrochemical Industry:

Crude oil transportation: In the process of oil exploration and transportation, crude oil and its associated media can be transported. Its good sealing and reliability can ensure the safety and efficiency of oil production. At this time, three-screw magnetic-driven pumps are required.

Refining process: In the refinery unit, it is used to transport various high-temperature, high-pressure, and corrosive media, such as transporting relevant liquids in the process of catalytic cracking, hydrocracking, etc. At this time, CQG - G series high-temperature and high-pressure magnetic pumps are required.

Mining Industry:

Metal smelting: It is used to transport electrolytes in the metal smelting process and wash the waste liquid generated during the smelting process, which helps to improve the efficiency and environmental protection of metal smelting. At this time, polyvinylidene fluoride (PVDF) material magnetic-driven pumps are required.

Mineral processing: In the mineral processing process, it can transport various slurries, acid solutions, and other media, providing fluid transportation support for each link of mining production. At this time, high-chromium alloy magnetic-driven pumps are required.

The dynamic seal of a centrifugal pump is a sealing method that relies on the centrifugal force of rotating components, and it can be divided into two categories: back-blade seal and auxiliary impeller seal.

Back - blade seal:

(1) Structure: Blades are added to the rear cover plate of the impeller of the centrifugal pump, and these blades rotate in the opposite direction to the impeller. These blades are back-blades.

(2) Working principle: When the centrifugal pump is in operation, the rotation of the impeller drives the back blades to rotate together. The centrifugal force generated by the rotation of the back - blades will throw the liquid at the rear cover plate of the impeller to the outer periphery of the impeller, reducing the liquid pressure at the rear cover plate of the impeller and forming a low-pressure area. As a result, it is difficult for the high-pressure liquid at the impeller outlet to leak through the gap between the impeller and the pump casing to the low-pressure area, thus achieving the sealing effect.

(3) Advantages: The structure is relatively simple, no additional complex devices are required, and the cost is low; it can balance the axial force of the centrifugal pump to a certain extent, reduce axial movement, and improve the operation stability of the pump.

(4) Disadvantages: The sealing effect is relatively weak, and it may not be suitable for some occasions with very high sealing requirements; the presence of back-blades will increase the frictional resistance of the impeller, resulting in a slight reduction in the pump's efficiency.

Auxiliary impeller seal:

(1) Structure: It usually consists of an auxiliary impeller, auxiliary blades (also called back-blades), fixed guide vanes, and a shutdown sealing device. The auxiliary impeller is a small centrifugal pump impeller, which rotates coaxially with the working impeller of the centrifugal pump.

(2) Working principle: During operation, the liquid leaked from the working impeller of the centrifugal pump flows to the auxiliary impeller. The centrifugal force generated by the rotation of the auxiliary impeller forms a pressure head, which can resist the high-pressure liquid at the outlet of the working impeller from leaking out, thereby achieving the sealing purpose. When the pump is shut down, the dynamic seal of the auxiliary impeller does not work. The liquid pressure inside the pump is small, and the liquid leaked to the auxiliary impeller is sealed by the shutdown sealing device. For example, three oil seals and one water-blocking ring are used for sealing.

(3) Advantages: The sealing effect is relatively good, and it is suitable for conveying media containing certain impurities because the influence of impurities on the auxiliary impeller is relatively small; during the operation process, the centrifugal force generated by the auxiliary impeller can also play a certain stirring role to prevent the precipitation of the medium.

(4) Disadvantages: The rotation of the auxiliary impeller consumes a certain amount of energy, which will increase the power consumption of the pump; the processing accuracy requirements of the auxiliary impeller are relatively high, and the manufacturing difficulty is relatively large.

The dynamic seals produced by Anhui Changyu Pump and Valve Manufacturing Co., Ltd. are all made of fiberglass - reinforced plastic. Due to the relatively low density of fiberglass - reinforced plastic, when the back - blades rotate, at the same rotational speed, their moment of inertia is relatively small. This means that during the starting and stopping processes, the back - blades need to overcome less inertial force and can reach a stable operating state or stop more quickly. From the perspective of the sealing principle, the fiberglass - reinforced plastic back - blades are stable in performance when the centrifugal force generated by rotation throws the liquid at the rear cover plate of the impeller to the outer periphery. Moreover, the good corrosion resistance of fiberglass - reinforced plastic can prevent changes in the blade surface caused by liquid corrosion, thereby maintaining the formation of a low - pressure area stably for a long time and ensuring the sealing effect. For example, in the working condition of transporting a mixed solution of acid, alkali, and salt with a certain concentration, the fiberglass - reinforced plastic back - blades can maintain the sealing performance more effectively compared with metal back - blades and reduce the situation of seal failure caused by corrosion.

The mechanical seal of a centrifugal pump is a high-performance sealing method. The following is a detailed introduction:

Structural composition

(1) Rotating ring and stationary ring: The rotating ring rotates with the pump shaft, and the stationary ring is fixed on the pump body and remains stationary. They are the key sealing elements of the mechanical seal. They are usually paired with hard materials (such as tungsten carbide, ceramic, etc.) and soft materials (such as graphite, impregnated graphite, etc.). The end faces of these materials are finely ground with extremely high flatness. For example, in some high-temperature and high-pressure application scenarios, the combination of tungsten carbide and graphite is often used. Tungsten carbide has high hardness and good wear resistance, and graphite has good self-lubricating properties and chemical stability.

(2) Spring: The spring provides the axial pre - tightening force for the mechanical seal to ensure that the end faces of the rotating ring and the stationary ring are always in close contact during the operation of the centrifugal pump. There are various types of springs, including single-spring and multi-spring forms. The single-spring structure is simple, but the force is unevenly distributed; the multi-spring can make the force distribution more uniform and is suitable for high-speed centrifugal pumps.

(3) Sealing ring: It is used to seal the gaps between the rotating ring and the shaft, the stationary ring and the gland, etc., to prevent liquid from leaking from these parts. The material of the sealing ring is selected according to different working conditions. Common materials include rubber (such as nitrile rubber, fluorine rubber, etc.) and polytetrafluoroethylene. For example, when transporting acidic media, fluorine rubber sealing rings can be selected because of their good acid resistance.

Working principle

During the operation of the centrifugal pump, the spring force and the liquid pressure act on the rotating ring together, making the end faces of the rotating ring and the stationary ring closely contact to form an extremely thin liquid film. This liquid film has a sealing effect and can also lubricate and cool the end faces. Since the rotating ring rotates with the shaft and the stationary ring is fixed, the existence of the liquid film can reduce friction and wear when the two are in relative motion, when the pressure inside the pump changes, the change in liquid pressure will also affect the sealing force between the rotating ring and the stationary ring, thus ensuring the sealing performance under different working conditions.

Advantages

(1) Good sealing performance: The leakage of the mechanical seal is extremely small, which can effectively prevent the liquid inside the pump from leaking. It is very suitable for some occasions with strict leakage requirements (such as centrifugal pumps for transporting toxic, flammable, and explosive media).

(2) Long service life: The high-quality materials of the rotating ring and the stationary ring and the reasonable structural design enable the mechanical seal to operate stably for a long time under normal working conditions, reducing the trouble of frequent seal replacement.

(3) Adapt to various working conditions: It can adapt to complex working conditions such as high temperature (some mechanical seals can work in a high-temperature environment of several hundred degrees), high pressure (the pressure can reach several megapascals or even higher), and high speed (high - speed centrifugal pumps), and has good sealing effects for clean media and media containing a small amount of impurities.

(4) Low power loss: Since the liquid film between the rotating ring and the stationary ring plays a good lubricating role and the friction coefficient is small, compared with the packing seal, the power loss of the mechanical seal is lower, which is beneficial to improving the operation efficiency of the centrifugal pump.

Disadvantages

(1) Complex structure: The mechanical seal has many components, and the structure is relatively complex, with high requirements for design, manufacturing, and installation. For example, the parallelism of the end faces of the rotating ring and the stationary ring is strictly required, and a slight deviation during the installation process may affect the sealing performance.

(2) High cost: The high-quality materials of the rotating ring and the stationary ring are expensive. Coupled with the precision processing technology and complex assembly requirements, the cost of the mechanical seal is much higher than that of other sealing methods such as the packing seal.

(3) Sensitive to impurities: If the medium contains more solid impurities or particles, the impurities may enter between the end faces of the rotating ring and the stationary ring, scratching the sealing surface and causing the seal to fail. Therefore, there are certain requirements for the cleanliness of the medium.

The mechanical seals produced by Anhui Changyu Pump and Valve Manufacturing Co., Ltd. have good sealing performance, long service life, can adapt to various working conditions, low power loss, and high processing precision. With strict factory - out inspection, the superior performance of the mechanical seals is ensured.