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What Is a Petri Dish?

A Petri Dish a type of laboratoryware made of glass.

The name “Petri Dish” comes from the German inventor, Julius Richard Petri. The name Petri dish is also of German origin.

Uses of Petri Dish

Petri dishes are used to hold test samples or to culture microorganisms or tissues. A petri dish, in particular, has excellent heat resistance and can be reused for sterilization by autoclaving after culturing bacteria and microorganisms.

A petri dish is a set of two cylindrical shallow dishes with slightly different diameters. The lid side is designed to be large and shallow, while the bottom side is small and deep. However, they are not hermetically sealed and are not suitable for culturing anaerobic bacteria and microorganisms.

Petri dishes come in a variety of sizes. The most common are about 10 cm in diameter and 1 or 2 cm in height, but there is also a taller version called a waist-high petri dish on the market.

Principle of Petri Dish

By preparing a culture medium in a petri dish and incubating it in an appropriate environment after inoculation, it is possible to observe the number of bacteria at the time of inoculation and the degree of growth of the bacteria from the number of colonies in the petri dish.

Petri dishes are highly transparent, making it easy to see what has been placed inside, and thus, cultured tissues and microorganisms can be observed directly under a microscope. The excellent heat resistance of glass petri dishes also makes sterilization possible.

A petri dish with a cover glass affixed to the bottom surface is also available, which enables observation under a microscope at high magnification and fluorescence observation. Since glass petri dishes can break if dropped, care should be taken when carrying them.

There are also heat-resistant petri dishes, which are made of a material that is more resistant to heat than ordinary glass. However, heat-resistant petri dishes are only heat-resistant, and their strength against impact is the same as that of other petri dishes.

Petri dishes with the bottom of the petri dish divided into three parts, which can be used to separate the contents of the petri dish, are also available.

Other Information on Petri Dish

1. Heat Resistance Temperature of Petri Dish

The heat resistance temperature of petri dishes varies depending on the manufacturer and product. Therefore, it is necessary to check the heat resistance temperature before heat treatment or sterilization.

Even though a petri dish is more heat resistant than other materials, it is strictly prohibited to heat it over an open flame using a burner. Rapid heating may damage a petri dish. When a petri dish is heated for experiments, an evaporating dish should be used.

2. Sterilization of Petri Dish

Petri dishes are generally sterilized by dry heat sterilization. Dry heat sterilization is a method of sterilizing microorganisms by heating them in dry air. It is used to sterilize glass and metal instruments that can be subjected to high-temperature treatment without problems or that should not be exposed to steam.

Dry heat sterilization can be done by either direct heating with gas or electricity or maintaining dry and hot conditions by circulating heated air. In the latter method, which maintains a dry, high-temperature state, sterilization is performed using dry heat sterilizers such as electric ovens.

The heating conditions are as follows: 3 to 5 hours at 135 to 145°C, 2 to 4 hours at 160 to 170°C, 1 hour at 170 to 180°C, and 30 minutes at 180 to 200°C.

Dry the petri dish well, make sure there are no water droplets on it, wrap it in aluminum foil, and place it in the dry heat sterilizer. When dry-thermally sterilizing multiple petri dishes, make sure that there is enough room in the chamber of the dry-thermal sterilizer and that the petri dishes are placed evenly. This is to ensure that all petri dishes are evenly heated.

Care must be taken to ensure that the metal parts of the dry heat sterilizer near the heater are not too hot, as they may be hotter than the set temperature. Turn on the sterilizer and measure the heating time after the inside of the chamber reaches the set temperature. When dry heat sterilization is complete, stop heating and wait until the chamber has cooled before removing the petri dish.

What Is a Bead Mill?

Bead Mills are machines for agitating and pulverizing wet powders and other media using particles called beads, which enable very fine grinding down to the nano-level. They are a technology generally manufactured within Japan.

The history of bead mills dates back to the postwar period in Japan, when Igarashi Machine Manufacturing (now AIMEX) completed Japan’s first bead mill based on technology owned by DuPont de Nemours, Inc. and mixed with its own original technology. After that, it went through a period of expansion due to Japan’s rapid economic growth, and a period of maturity after the Heisei era, leading up to the current state-of-the-art bead mill.

Uses of Bead Mills

The main example of actual use of bead mills in the market is the grinding of various objects. The objects are food, metal oxides for glass layers on the surface of ceramics, iron oxide for magnetic tape, barium titanate for ceracon in laminates, and various other objects, which are used in many grinding applications.

Recently, nano-dispersion needs have been increasing. For example, the bead mill is being utilized to disperse particles of 100 mm or smaller in the dispersion of organic pigments used in LCD color filters, zirconia for hard coatings, and titanium dioxide for cosmetic applications.

Principle of Bead Mills

In a wet bead mill, a vessel is filled with a slurry in which beads and particles are dispersed, and the slurry is agitated at high speed by a stirring rotor, causing the beads and particles in the slurry to collide with each other, resulting in particle size reduction.

Bead Mills make it possible to adjust the amount of energy imparted to the particles by changing the size of the beads used.

For example, grinding hard particles or reducing them to a smaller particle size requires strong energy, which requires relatively large beads to be brought into contact with each other at high speed.

On the other hand, with smaller beads, the collision energy is lower, but the processing speed can be increased because the number of collisions with particles is increased by increasing the bead volume.

Smaller beads are also more suitable for dispersion, since strong milling with larger beads results in excessive particle milling and re-agglomeration of particles. Thus, the energy of grinding and dispersing affects the size and hardness of particles that can be subdivided as well as the processing speed, and the frequency with which beads and particles collide with each other also affects the speed at which they are processed.

The size of the space in which the beads move is also an important factor that also has a significant impact.

How to Select a Bead Mill

In the principles, we mentioned the influence of bead size and speed on milling performance. On the other hand, it is necessary to separate the beads from the milled particles, and the performance of the bead mill is also important for this method. There are three main separation methods: slitting, screen, and centrifugal separation.

The slit method separates slurry by passing it through a narrow gap. Basically, beads of 0.3 mm or larger are used and can be used stably even with viscous slurries. The screen method is similar to the slit method in that it uses a gap to separate slurry, and beads of 0.1 mm or larger are used.

The centrifugal separation method uses centrifugal force to separate slurry and beads, and can be applied to beads smaller than 0.1 mm.

As explained above, the size of the beads greatly affects the grinding capacity. Slit and screen methods are often employed for submicron-level milling, while centrifugal separation methods are often employed for nano-sized milling and dispersion.

What Is A Pipettor?

Figure 1. Various pipettors

A pipettor is an instrument that is attached to a pipette, such as a whole pipette or a female pipette, and performs the pipetting action of sucking up and dispensing solution.

Alternatively, it may refer to a pipette that has its own aspirating function. Pipettors include manual safety pipettors, pipette pumps, and electronic pipettors.

Recently, electronic pipettors are the most common; they can set the pipette volume with a dial on the hand, aspirate with a single push of a button, and dispense with a single push of a button.

Uses of Pipettors

Pipettors are used throughout the chemical and biological fields for all pipetting operations in which a fixed amount of liquid is aspirated to measure or dispense into another container.

Examples of liquids used include solvents, solutions, samples, media, additives, etc. Micropipettors are also commonly used for the injection of minute amounts of liquids of 1 mL or less.

Hole pipettes and scalpel pipettes were used in the past to suck up solutions by mouth. However, since it is dangerous to aspirate chemicals, especially hazardous substances, by mouth using pipettes or female pipettes, Pipettors are now commonly used as an alternative.

Manual and automatic pipettors are used for aspirating and dispensing a certain amount of organic substances, etc., because only the tip of the pipette is wetted and the tip can be removed without being touched.

Principles of Pipettors

Figure 2. Using the Safety Pipetter

One type of pipettor, the safety pipettor, is a manual type that is attached to a female pipette or similar instrument. The air intake valve is pressed to depress the rubber ball, the liquid intake valve is pressed to suck up the liquid, and the discharge valve is pressed to drain the liquid.

Instructions for use are as follows:

1. While pressing A, release the air inside the large rubber ball
2. Insert a pipette.
3. Put the pipette tip on the solution and press S to suck up more sample
4. Press E to adjust to the scale
5. Align the pipette tip with the container you want to dispense from and press E to dispense the solution
6. Since a little liquid remains at the tip of the pipette, press the rubber ball to dispense while plugging the hole at the tip of E.

Pipette pumps are constructed with a piston that moves air in and out by moving the piston up and down. The distance it moves up and down can be finely adjusted with a dial, and the amount of air that is moved in and out can be finely adjusted, making it possible to precisely and accurately adjust the amount of liquid.

Electronic pipettors use a motor to perform a series of operations that are labor-saving and can be done at the touch of a button. Most products on the market today are powered by rechargeable batteries. However, recharging time and whether the product can be used while recharging vary from product to product.

While a regular pipette needs to be cleaned and dried each time a chemical is changed, manual and motorized pipettors allow for the immediate injection of a different liquid by simply replacing the pipette tip that is wetted. The pipettes are designed to be removed without touching the tip, eliminating the risk of hazardous substances adhering to the body and improving not only workability, but also safety.

How to Select a Pipettor

Figure 3. Pipettor with pipette attached

Since each pipettor has its own characteristics, it is important to select the appropriate one for your experimental use and purpose.

First, identify the volume of liquid to be handled in one pipetting run in the experimental system you wish to use: a micropipette may be appropriate for small-scale experiments involving less than 1 mL, while a graduated pipette is appropriate for those involving more than 100 mL. A safety pipettor, pipette pump, or motorized pipettor is then preferred.

Most electric pipettors can handle female pipettes with a lower limit of 0.5mL or 1mL and an upper limit of 100mL. Pipette pumps are available for 2mL, 10mL, and 25mL. Also note that charging time, usability during charging, and aspiration/dispensing speeds vary from product to product.

In order to obtain accurate experimental data, products should be considered from the perspective of contamination prevention when selecting a product. It is desirable to select a product with a cap and filter that are designed for easy cleaning. In addition, it is recommended that caps and filters be autoclavable for biological experiments.

What Is a Gas Detector?

A gas detector is a machine that measures the concentration of a target gas. There are various types of gas detectors, ranging from those used to detect gas leaks in homes to those used in industrial settings. All of these detectors are used to protect the safety of workers by alerting them to the presence of gases.

For residential use, the target gases are city gas and propane gas. For industrial use, detectors are used to measure oxygen concentration and detect toxic gases such as carbon monoxide and hydrogen sulfide, as well as flammable gases such as organic solvents.

Uses of Gas Detectors

Gas detectors are widely used in gas production, chemical plants, semiconductor factories, tunnel construction sites, the steel industry, agriculture, and homes. Gas leakage can cause a variety of hazards.

For example, leakage of flammable gases can lead to large-scale problems such as fires and explosions. Toxic gases can cause health hazards to workers and environmental pollution. Oxygen concentrations below a certain level can cause workers to die of asphyxiation.

Gas detectors are used to quickly detect and notify workers of gas leaks that could cause these serious accidents. Therefore, the appropriate type of gas detector must be selected for each application.

Types of Gas Detectors

1. Classification by type of object to be measured:

• Single-component gas detector: A single unit is used to measure one type of gas. Compact, lightweight, and easy to handle
• Combined gas detector: A single unit can be used to measure multiple types of gases. It can measure a wide range of gases, such as combustible gases, toxic gases, oxygen, etc., and is used at various factories and work sites to ensure safety.

2. Classification by installation method:

• Portable detectors: Portable detectors are worn by workers and used to measure gases during work and notify workers of an abnormality when a gas is detected.
• Stationary detectors: Continuously measure gas concentrations within a plant facility, contributing to stable plant operation. When used in large facilities, the detector and alarm sections/systems can be separated to monitor multiple locations at once.

Principle of Gas Detectors

Gas detectors can detect a wide range of gases and analyze them in a variety of ways. For many sensors, organosilicon gases, corrosive gases (SOx, NOx, etc.), and acidic gases (HF, HCl, etc.) are gases that cause deterioration (= miscellaneous gases). In addition, gases other than the target gases, such as hydrocarbons, alcohols, and organic solvents, can in many cases, interfere with accurate measurements (interference gases).

It is important to check in advance the type of sensor built into the detector you are considering using and the corresponding type of miscellaneous or interfering gases. The principle of each type of sensor and the gases to be measured are described below.

1. Semiconductor Type

This sensor uses the change in resistance that occurs when a semiconductor comes into contact with a gas. It has high sensitivity and can measure even low concentrations. Target: Flammable gases, toxic gases

2. Thermal Semiconductor Type

Instead of a semiconductor used in the semiconductor type, a platinum wire coil and a semiconductor are integrated. It is characterized by its high sensitivity and suitability for miniaturization. Target: Flammable gases, toxic gases

3. New Ceramic Type

This type utilizes the heat generated when combustible gas burns on a new ceramic (ultrafine particulate oxidation catalyst). It can measure a wide range of concentrations and is expected to operate stably. Target: Combustible gas

4. Catalytic Combustion Type

Platinum, an oxidation catalyst, is heated to a high temperature, and when gas strikes it, a combustion reaction occurs, and the temperature rises. This temperature change is used for detection. Excellent accuracy and reproducibility. Target: Combustible gas

5. Constant Potential Electrolysis Type

Detects the electric current generated when the gas is electrolyzed on the electrode. The target gas can be selected by setting the potential and is not easily affected by interfering gases. Target: Toxic gases

6. Diaphragm Galvanic Battery Type

A galvanic battery is built inside. When gas permeates through the diaphragm inside the battery, a reaction occurs between the two electrodes, generating an electric current. The strength of this current is used as the concentration of the target gas. The built-in battery can be operated without an external power supply. Target: Oxygen

7. Non-dispersive Infrared Type

Each type of gas has the property of absorbing infrared rays at specific wavelengths. The concentration of the gas is calculated from the amount of infrared radiation absorbed at the measurement wavelength. It can be operated stably over a long period and has high selectivity for the target of measurement. Target: Combustible gases, toxic gases

8. Lightwave Interferometry

Detects gases based on changes in the refractive index of the gas. It can be operated with stable accuracy for a long period. Object: Combustible gases

9. Thermal Conduction Type

The temperature of the detector element rises when the hot element comes into contact with the gas. The gas concentration is calculated from the value of the temperature change and the change in resistance of the element. Suitable for measurement of highly concentrated gases. Target: Combustible gases

What Is a Gas Chromatograph?

A gas chromatograph is an instrument used for qualitative and quantitative analysis of easily vaporizable compounds. It is commonly abbreviated as gas chromatography and is sometimes written as GC, from the English abbreviation Gas Chromatograph. Along with high-performance liquid chromatography, it is a very well-known analytical technique.

Its principle is to vaporize a sample and then separate each component to determine the type and content of compounds. The greatest advantage of this method is that it can analyze volatile components even at very low concentrations. Currently, gas chromatographs are used in a wide range of fields, including pharmaceutical, food, and chemical industries, contributing to the foundation and development of science and technology.

Gas chromatography and gas chromatography are similar terms, and the two are often confused, but the former (gas chromatograph) refers to “experimental equipment” and the latter (gas chromatography) refers to “separation operations using gas chromatography”.

Uses of Gas Chromatographs

Gas chromatographs are used for the separation and analysis of compounds in the fields of medicine, food, and chemistry. For example, it can be used to measure the concentration of hazardous substances and to analyze the components of gases generated in equipment. Note, however, that not all compounds can be analyzed. Due to its principle, gas chromatography generally cannot analyze non-volatile compounds with a boiling point of 400°C or higher, or unstable compounds that decompose at high temperatures. Inorganic metals, ions, and highly adsorbable compounds are also difficult to analyze for the same reason and must be confirmed before analysis.

Principle of Gas Chromatography

The principle of gas chromatography is very simple and consists of the following three steps:

1. Vaporize the sample by heat
2. Separate the components by column chromatography
3. Detection of the components by an appropriate method

First, the liquid sample is thermally vaporized. The vaporized components are transported to the column by a carrier gas. The vaporized components are adsorbed and distributed to the stationary phase (liquid phase) in the column, separated by component, and passed through the column. Since the speed at which compounds move through the column differs depending on the compound, the components with the fastest movement speed are first separated from the column. Since each separated component is recorded as a peak by the detector, the type and concentration of the sample can be determined by comparing the retention time and peak area with those of the standard.

The main feature of this analytical method is that it can analyze volatile components that cannot be separated, identified, or quantitated by high-performance liquid chromatography.

About the Stationary Phase Used in Gas Chromatography

The selection of the stationary phase to be used in the column of gas chromatography is very important. If a column with an appropriate stationary phase is not used according to the characteristics of the components, separation and analysis will be difficult.

Columns are broadly classified into two types based on the polarity of the stationary phase: nonpolar columns and highly polar columns.

1. Non-polar Columns

A non-polar column is a column in which a compound with low polarity is used as the stationary phase. In such columns, low-polarity compounds are strongly retained in the low-polarity liquid phase as the stationary phase, resulting in slower migration rates and, thus, higher separation performance. Therefore, non-polar columns are suitable for the analysis of nonpolar compounds. In addition, nonpolar columns are more heat resistant than highly polar columns and can generally be used up to 350°C.

2. Highly-polar Columns

A highly polar column is a column in which a highly polar compound is used as the stationary phase. In such columns, highly polar compounds are strongly retained, which slows down their migration rate and results in high separation performance. As a result, these columns are suitable for the analysis of highly polar compounds. Also note that high polarity columns have low heat resistance, generally with an upper limit of around 250°C.

Separation of Highly Polar Low-Molecular-Weight Organic Compounds by Derivatization 

Due to their low volatility, highly polar organic low-molecular-weight compounds are generally difficult to separate and analyze using gas chromatography. However, depending on the structure of the target compound, it may be possible to derivatize it into a volatile compound using chemical methods, in which case separation using gas chromatography becomes possible. Therefore, such derivatization techniques are widely used for separating and analyzing compounds that are difficult to separate by high-performance liquid chromatography. One such example is the TMS derivatization of sugars and oligosaccharides, compounds with many hydroxyl groups, followed by GC analysis.

A detector in Gas Chromatography

Detectors detect components separated by gas chromatograph columns and are used for different purposes.

1. Flame Ionization Detector (FID)

Flame Ionization Detector (FID) detects ionized compounds by combustion of organic compounds in a hydrogen flame formed by air and hydrogen. Almost all organic compounds can be detected, and the sensitivity is extremely high.

2. Thermal Conductivity Detector (TCD)

Thermal Conductivity Detector (TCD) defects components by reading the temperature change of a filament based on the difference in thermal conductivity between the carrier gas and the target component. Both inorganic and organic components can be detected nondestructively.

3. Flame Photometric Detector (FPD)

Thermal Conductivity Detector (TCD) detects each component by amplifying the light of a specific wavelength generated from the element by combustion using a photomultiplier tube and converting the intensity of the light into an electrical signal. Sulfur compounds, phosphorous compounds, and organotin compounds can be detected.

4. Sulfur Chemiluminescence Detector (SCD)

Sulfur components are detected by measuring the light produced when chemical species (mainly SO) converted from sulfur compounds are excited by ozone and then return to their ground state using a photomultiplier tube.

5. Nitrogen Phosphorus Detector (NPD)

This detector is suitable for the measurement of organic nitrogen compounds. When a compound containing phosphorus or nitrogen enters the rubidium salt in the hydrogen flame, it ionizes to form CN- and PO- ions, which are detected.

6. Electron Capture Detector (ECD)

This detector is used for the selective detection of compounds with high neoelectronicity, such as organohalogen compounds, organometallic compounds, and nitro compounds. Components are detected by reading changes in voltage values to keep the ion current collected in the collector constant.

Gas Chromatograph-Mass Spectrometer

A gas chromatograph-mass spectrometer is an instrument that combines a gas chromatograph and a mass spectrometer via an interface. First, a sample containing multiple components is separated into single components by the gas chromatograph, and then the mass spectrometer measures the MS spectra of the individual components to qualify the components and quantitate them from the spectral intensity of the ions.

Gas chromatograph-mass spectrometers are suitable for compositional analysis of various oils, qualitative analysis of organic solvents, qualitative and quantitative analysis of gases generated from various materials and pyrolysis-generated gas species, and VOC (volatile organic compounds) analysis in air, water, etc.

What Is an Orifice Plate?

An orifice plate is a thin metal plate with a perforation (hole) process that controls fluid flow and pressure when installed in a pipe.

There are four major types of orifice plates; concentric orifice, eccentric orifice, four-part circular orifice, and restricted orifice plates.

Concentric orifice plates are used in aperture flowmeters such as general differential pressure flowmeters.

Quadrant orifice plates are used when the flow rate in the piping is low and the Reynolds number is small. A Reynolds number is a dimensionless number that is the ratio of inertia force to viscous force.

Eccentric orifice plates are used when the fluid contains slurry (a mixture of solid particles and liquid). The slurry can flow easily by installing an orifice hole on the lower side of the pipe. The use of a deflection orifice plate is the same as that of an eccentric orifice plate.

When an orifice plate is installed in piping it is sandwiched between flanges and used as an assembly. Sometimes, like shock absorbers, orifice plates are used pre-assembled into products.

Applications of Orifice Plates

Orifice plates are used in a variety of flow and pressure control applications in industrial applications and industrial piping. As an example of differential pressure flowmeter use, an orifice plate is used to measure the flow rate of a fluid in a pipe as a differential pressure flowmeter. Fluid is extracted from the flanges before and after the orifice plate, and the differential pressure is converted into a flow rate and displayed on the indicator.

Orifice Plate Uses

For the regulations when an orifice plate is used for flow measurement in this manner, refer to JIS Z 8762-2, methods of flow measurement by an orifice mechanism in a circular pipeline. Shock absorbers take advantage of the high pressure drop across the orifice plate. The smaller the orifice hole diameter, the higher the fluid pressure drop and the greater the damping force of the shock absorber. Conversely, a larger hole diameter results in a smaller damping force.

Principle of Orifice Plates

To briefly explain the orifice plate principle, the fluid pressure is lower downstream of the orifice than upstream of the orifice based on Bernoulli’s theorem because the orifice hole’s inner diameter is smaller than the pipe’s inner diameter where the orifice plate is installed. Bernoulli’s theorem is a law of conservation of energy in fluid flow. When a fluid passes through a small hole in an orifice, a pressure difference occurs before and after the orifice in the pipe. This is due to Bernoulli’s law, which states that pressure energy, velocity energy, and potential energy are always constant in a pipe.

The fluid immediately after passing through the orifice plate has a higher velocity and the velocity energy increases. If the potential energy is the same, then the pressure energy decreases by the same amount as the velocity energy increases. By measuring this difference in pressure before and after the orifice plate, the flow rate of the fluid can be calculated. When an orifice plate is used to regulate flow or pressure, the flow rate downstream of the orifice plate can be determined based on the following equation:

What Is an Oil Filter?

An Oil Filter is a filter that removes sludge, wear particles, and debris from engine oil, hydraulic oil, and other oils.

For automobiles, it is sometimes called an oil element, and is often used in automobiles and industrial machinery.

Oil gradually oxidizes and becomes dirty as the machine operates. Continued use of dirty oil can lead to machine breakdowns, so the oil must be filtered through an oil Filter.

As filtration causes dirt to accumulate in the filter, periodic replacement is necessary.

Uses of Oil Filters

Oil Filters are widely used in various types of engines and other industrial machinery. Specifically, they are used in automobile engines, automatic transmissions, marine engines, generator engines, and gas turbines.

It is also used in vacuum pumps, agricultural machinery such as mowers and sprayers, hydraulic equipment operating oil, lubricating oil for various machines, and cutting oil for machine tools.

Oil contamination can be caused by the following three factors:

• Oil that has been in the oil circuit from the beginning
• Oil that enters from the outside
• Oil that is generated during machine operation

The first two can be prevented by the structure of the machine and the way it is handled. However, the third point is mainly caused by oxidation and cannot be prevented. Therefore, it is important to use oil filters to keep the oil clean.

Principle of Oil Filter

In general, oil filters remove contaminants by allowing oil to pass through a porous filter material.

Other filtering methods include adsorption by magnets and centrifugal force by increasing the flow velocity. To remove contaminants, the pores in the filter media must be smaller than the contaminants, or the contaminants must be able to adhere to the filter media walls.

Oil filters can be divided into the following three types:

1. Full-Flow Type

The Full-Flow type is used to filter all oil. A bypass valve is generally built in, and this type is widely used in passenger car engines today. 

2. Full Flow + Bypass Type

Oil is filtered by dividing the oil flow path into two separate paths, one with a full-flow filter and the other with a bypass filter. The bypass filter can remove smaller contaminants than normal. This type of filter is mainly used in diesel engines.

3. Combination Type

This type combines a full-flow filter and a bypass filter into one. Oil flowing in the flow path is divided into these two filters. This type is used for large diesel engines.

Types of Oil Filters

There are three main types of oil filters:

1. Screen Type Oil Filter

A very fine metal mesh is attached to the oil inlet in the oil pan for filtration. Most engines today use both a filter paper type oil filter and a screen type filter. 

2. Built-in Oil Filter

An oil filter made of filter paper is built into the engine or oil pan near the oil strainer. This type of filter is used in motorcycles of relatively old design. In addition, automatic transmissions and continuously variable transmissions for automobiles have a replaceable ATF filter built into the strainer. 

3. Cartridge Type and Spin-on Type

The cartridge type installs a removable cartridge outside the engine. The cartridge is reused many times, and only the filter inside is replaced periodically. Compared to the built-in type, the cartridge type requires no opening of the oil pan or other parts of the engine, thus improving serviceability.

The spin-on type, which appeared in the 1950s, has a filter paper oil filter and various valves all built into the casing. It is installed by rotating it directly over the oil passageway on the engine side, and the filter media is discarded with the casing each time the oil filter is replaced. This type of oil filter is used in most automobiles today because it makes replacement work more efficient.

Other Information on Oil Filters

Oil Filter Replacement

When dirt accumulates in the oil filter, the filter becomes clogged and the amount of oil circulating through it is reduced. In this case, the bypass valve opens and the oil barely circulates, but the oil that passes through the bypass valve is not filtered by the oil filter, which causes the filter to deteriorate.

Periodic replacement of the oil and oil filter is necessary because the oil degradation and clogging of the oil filter will cause damage to the equipment. Replacement times are clearly indicated in the manufacturer’s instruction manual.

In the case of automobile engines, engine oil and oil filters must be replaced properly because the use of dirty engine oil can cause engine damage, reduced fuel efficiency, and loss of power. Many manufacturers clearly state when to change the oil and recommend changing the oil filter every two oil changes.

What Is an Elbow Pipe Fitting?

An Elbow Pipe Fitting is a type of pipe fitting used to bend a pipeline flow path 90 or 45 degrees. They are called 90-degree elbows and 45-degree elbows, respectively. Bends are similar to elbows in that they are manufactured in a different way.

The connection method of elbow pipe fittings vary depending on the surrounding environment and the bore size. There are several types, such as flange connections when open piping is expected, and welded connections when leakage prevention is desired.

Uses of Elbow Pipe Fittings

Elbow Pipe Fittings are used to change the direction of piping. For example, in everyday life, elbows are found in water and sewage piping, and in industrial applications, elbows are often used in factory water piping.

Elbow pipe fittings cause pressure loss, so they must be designed according to Fanning’s formula to minimize the number of elbows.

There are two types of elbows: long elbows and short elbows. Short elbows have a small radius of curvature and thus save space. Long elbows have a large radius of curvature but are available at a lower cost. Generally, long elbows are used.

Principle of Elbow Pipe Fittings

The working principle of an elbow pipe fitting is to bend the flow of fluid by decelerating the fluid at the point of bending. Elbows play an essential role in properly controlling the flow of fluid inside a piping system and ensuring that the piping system functions properly.

Elbows are made of metals such as chrome or nickel, depending on the material. Depending on the material, elbows are characterized by high corrosion and wear resistance and can withstand repeated use.

Elbows can be connected by either a screwed-in or welded connection method. The screw-in type is connected by screwing it into the piping, which is easy to remove, but is not as strong and may cause leakage. On the other hand, the welding type connects pipes by welding them together, which is stronger and less likely to cause leakage, but has the disadvantage of being difficult to remove.

Other Information on Elbow Pipe Fittings

1. Elbow Pipe Fitting Materials

There are various types of elbow fittings depending on the material. The most commonly used is made of malleable cast iron. They are called black fittings because of the color of the material. A hot-dip galvanized joint made of the same material is called a white joint.

Stainless steel fittings are used to prevent corrosion.

2. Types of Elbows and Piping

There are two types of connections between elbows and piping: threaded and welded.

1. Screwed-in type

This is a method in which the elbow and piping are each threaded. Since the elbow and piping are simply screwed together, there is no need for bolts and nuts. Also, on-site welding is not required, so it can be installed in fire-prohibited areas. However, the larger the bore size, the more difficult it is to seal and install. Therefore, flanged or welded connections should be used for larger diameters.

Threaded elbows are generally installed with sealing tape wrapped around them. The direction of the sealing tape should be in the direction of tightening. 

2. Welding type

Elbows are connected to pipes by welding. Accurate welding prevents leakage. However, the degree of completion depends on the skill of the welder. There is a risk of corrosion due to poor welding.

Difference Between Elbows and Bends

Elbows and bends are manufactured in different ways. Bends themselves are manufactured by secondary processing of formed pipes. In other words, the pipe is manufactured by bending it.

Elbows, on the other hand, use a process called Hamburg bending (hot expanding mandrel process). By bending a steel pipe while expanding it, this manufacturing method prevents differences in wall thickness between the inside and outside of the elbow.

What Is an Etchant?

Etchant is an agent that corrodes metals and metal oxides and is used to process substrates. Compared to processing methods such as pressing, etching is a method with superior microfabrication properties, and wet etching methods using etchant are more cost-effective and easier to mass-produce than dry etching using gases. The type of compound that reacts differs depending on the type of metal, so the appropriate etchant should be selected according to the substrate material.

Since etchant often contains strong acids, strong bases, and toxic compounds, it is necessary to select protective equipment and take safety measures prior to use.

Etchant Applications

Etching is a method of processing metals such as gold and aluminum, and metal oxides such as indium tin oxide (ITO) by immersion removal. There are two types of etching: dry etching, which uses gas, and wet etching, which dissolves the metal in a solution.

Compared to press processing, etching enables fine processing and is used in the production of printed circuit boards, semiconductor devices, and displays. In manufacturing, the two methods are used separately: dry etching is used when precision processing is required, and wet etching is used when cost and mass production are required.

Etching Methods and Etchant Types

Dry etching is an etching process using gas or plasma. It is superior in microfabrication, but requires special conditions such as a vacuum, making it costly and unsuitable for mass production.

Wet etching, on the other hand, uses etchant containing compounds that corrode metals. Different compounds react and dissolve differently with different types of metals, so a variety of etchants are available.

For example, some etchants contain strong acids such as hydrochloric acid and nitric acid, strong bases such as sodium hydroxide, and heavy metal ions with high oxidizing power such as iron(III) chloride.

Etchant Effluent Treatment

Etchant dissolves metals by ionizing them, so the liquid after use contains a large amount of heavy metal ions. Therefore, untreated etchant effluent cannot be discharged into the environment. Therefore, etchant waste treatment is generally outsourced to a specialized waste treatment company.

Since etchant effluent contains strong acids and bases, there is a risk that the container may corrode during storage, depending on the container material. Therefore, it is important to first select an appropriate container with chemical resistance. Etchant may be irritating to the skin and eyes before or after use. When handling etchant, the Safety Data Sheet (SDS) should be carefully read in advance, and appropriate protective equipment should be worn and handled with extreme caution.

What Is Urethane Resin?

Urethane resin is a generic term for polymers produced by the polyaddition reaction of compounds with isocyanate groups and hydroxyl groups. The bonding site is called a urethane bond (Figure 1) and is generally formed by the polyaddition of diisocyanate and polyol.

As abbreviation symbols, PU is used for plastics and U for rubber. Urethane resins have excellent tensile strength, abrasion resistance, oil resistance, and chemical resistance and are therefore also applied in paints and coatings. However, they also have the disadvantage of gradual degradation due to hydrolysis and ultraviolet rays.

Applications of Urethane Resin

Urethane resins are used in a wide range of applications, from familiar household goods to industrial products, due to their high versatility. Examples of familiar products include clothing and car bumpers, while industrial applications include soundproofing materials and adhesives.

It is also used in the soles of sports shoes due to its high flexibility and is one of the resins that are indispensable in our daily lives. This material has a history of being used as a substitute for natural rubber. Therefore, the development of applications utilizing its high elasticity and tensile strength, which are characteristics of rubber, is underway.

Environmental Residuality and Recycling of Urethane Resin

Urethane resin is widely used as a heat insulator for refrigerators, freezers, and coolers because of its excellent heat insulation properties. However, their chemical properties make them difficult to recycle and post-process, and this is an area that is the subject of ongoing research.

The decomposition and recycling technologies have already been established, including thermal decomposition, hydrolysis, glycol decomposition, ammonia decomposition, and amine decomposition, but there are still problems to be solved in terms of decomposition efficiency and cost.

Characteristics of Urethane Resins

Urethane resins have excellent flexibility, impact resistance, tensile strength, and chemical resistance, but they deteriorate after about 3 years. While it has many of these characteristics, its properties vary greatly depending on the manufacturing method.

Degradation can be caused by a wide variety of factors, including oxygen, ozone, light, and heat, hydrolysis through reaction with water, and decomposition by microorganisms. In addition, polyurethanes are characterized by the ability to change their physical properties depending on the manufacturing method. As a result, there are various types of polyurethane resins depending on their intended use. Typical examples are as follows.

1. Foam Type

Foam type is a urethane resin in which air is incorporated into the resin by adding a foaming agent and polymerizing. This material is divided into soft urethane foam and hard urethane foam. The former is used for automobile seats, etc., because of its superior cushioning and durability and lightweight. The latter has excellent heat insulation properties and is used as a heat insulator for refrigerators, freezers, and air conditioners.

Among urethane foam manufacturing methods, slab molding, molding, and laminate molding require large-scale manufacturing equipment. On the other hand, the spray foaming method can be easily handled because the foam can be mixed and foamed on the spot at the point where insulation is needed.

2. Non-foam Type

A typical example of a non-foam type is an elastomer, or urethane resin with rubber elasticity, which is used in sports shoes. Because of their high elasticity, urethane resins with such properties are used for sportswear and slacks.

Differences Between  Urethane, Epoxy  and Acrylic Resins

Although these three terms are often used interchangeably, perhaps because they all contain the word “resin,” they refer to completely different materials.

Urethane resin is a generic term for a polymeric material with urethane bonds, as explained at the beginning of this article. On the other hand, epoxy resins refer to thermosetting resins with reactive epoxy rings at the ends of their molecules.

Acrylic resin is also a polymer or copolymer of acrylic acid and its derivatives. In other words, their meanings are strictly defined by their different structures and chemical properties, so care must be taken in their usage. 

Adhesives 

There are two types of adhesives: solid adhesives, such as double-sided tape and seaming tape, and liquid adhesives, in which the applied adhesive is pressed and cured to produce an adhesive effect.

Liquid adhesives can be classified into two major types based on the adhesion method: dry-setting type and reaction-curing type. In the dry-setting type, adhesion occurs when the water or solvent contained in the adhesive volatilizes. On the other hand, the reaction curing type is an adhesive that uses curing caused by a chemical reaction between the components contained in the adhesive.

Reaction curing type can be further classified into two types. One is epoxy resin-based adhesives, in which the main agent and hardener cause curing, and the other is urethane resin-based adhesives, in which curing is caused by moisture in the air. Among these, urethane resin-based adhesives are used in a wide range of general applications because of their high adhesion and quick bonding, making them versatile.

Floor Coating Agents Using Urethane Resins

Floor coating agents can be classified into two types: water-based and oil-based. Originally, coating agents using urethane resins were also divided into water-based and oil-based systems. However, since there were questions about the safety of oil-based systems, water-based systems are generally used today.

Water-based urethane coating agents are characterized by lower durability than oil-based floor coating agents such as glass and silicone coatings. However, they also have the feature that they can be finished at a lower cost. Therefore, compared to other floor coating agents, water-based urethane coating agents are often chosen.

The advantages of choosing water-based urethane coatings are that they are quick-drying due to their fast curing speed and that they are virtually odorless, without the volatile odor of thinner. In addition, it is compatible with most flooring materials, so it can be used for any type of flooring.

On the other hand, one demerit is deterioration over time, which can be considered a weakness of urethane resins. Most water-based urethane coatings have a durability of 10 years or less. However, in addition to the aforementioned merits, water-based urethane coating agents are still chosen as popular coating agents because of their superior safety and ease of use.