月: 2022年12月

What Is a Hydraulic Torque Wrench?

A hydraulic torque wrench is a torque wrench that can apply large force powered by hydraulic pressure.

Hydraulic torque wrench is mainly used for fastening large bolts because it can generate large torque with a small force.

Hydraulic torque wrench consists of three major parts.

• Hydraulic Piston
  Converts the pressure energy of the hydraulic fluid into kinetic energy
• Ratchet
  Restricts the direction of movement to one direction using a tooth stop
• Casing
  Discharges oil efficiently

The hydraulic pump can also be used in explosion-proof areas by using an air hydraulic pump.

Applications of Hydraulic Torque Wrenches

Hydraulic torque wrenches are used in the following situations where medium to large bolts and nuts need to be tightened or loosened.

• Electric power generation facilities
• Petrochemical
• Ironworks
• Shipyards
• Shield tunneling
• Construction Machinery
• Construction of large structures

Shield tunneling, among others, takes advantage of the benefits of hydraulics, which can be used even when the power source is far away. The use of long hydraulic hoses makes it possible to tighten bolts underwater and flange bolts of submarine cables.

Principle of Hydraulic Torque Wrenches

Hydraulic torque wrench uses “Pascal’s Principle” which can generate large torque with a small force using hydraulic pressure.

1. What Is Pascal’s Principle?

Pascal’s principle is a law that states that when a certain amount of force is applied to a sealed container of liquid, the pressure is equal in all directions without decreasing the volume.

For example, suppose the pressure and cross-sectional area applied to a container are as follows

• Pressure: 1.0 MPa
• Cross-sectional area at input: 10 cm2
• The cross-sectional area of the output side: 100 cm2

In this case, the following torque is required to maintain the same pressure.

• Force required for input: 100 kg
• Force that can be output: 1,000 kg

Thus, since a large output can be obtained with a small input, a hydraulic torque wrench is used for automobile brakes and hydraulic jacks, as well as a hydraulic torque wrench.

2. Principle of Tightening Bolts and Nuts

Hydraulic torque wrench makes it easy to tighten bolts and nuts.

1. Pressure is increased by hydraulic oil in a pressure pump.
2. The hydraulic piston is moved by hydraulic pressure.
3. The hydraulic piston pushes the push pawl (ratchet ball) linked to the ratchet, changing the force into a rotational force.
4. The rotational force moves the ratchet.

At this time, the ratchet does not rotate to the specified torque in a single stroke but rotates approximately 30 degrees in each stroke. In addition, the ratchet mechanism includes a reaction plate, which moves only in one direction. Therefore, the bolt does not reverse when the piston returns.

Other Information on Hydraulic Torque Wrenches

1. Advantages and Disadvantages of Using Hydraulic Torque Wrench

• Small and lightweight, therefore easy to carry
• High tightening accuracy (accuracy within ±3%)
• Less noise during operation compared to impact wrenches, etc.

These are the advantages of using a hydraulic torque wrench. In particular, the low noise level during operation is a unique advantage of the hydraulic torque wrench. For example, when you want to excavate a tunnel at night on the ground, you are less likely to disturb the neighbors.

However, the hydraulic torque wrench has the disadvantage of slow working speed. However, it is possible to reduce the working time by connecting two units.

2. How to Use a Hydraulic Torque Wrench

1. Connect a socket and a hydraulic hose to the hydraulic torque wrench and the hydraulic pump.
2. Check the set pressure from the torque conversion table.
3. Set the pressure of the hydraulic pump.
4. Set the hydraulic torque wrench on the bolt to be tightened.
5. Turn on the hydraulic pump.
6. Tighten the bolt until it stops rotating.

A torque conversion table is often enclosed with the hydraulic torque wrench. If you do not have it, there are websites where you can convert units on the web.

Tightening is complete when the pressure rises to the set value but the ratchet does not turn. Insufficient tightening can cause accidents or injuries, so be sure to check the tightening.

What Is an Oil-Filled Transformer?

An oil-filled transformer is a transformer that uses oil as an insulating material.

The primary insulating oil is mineral oil. A transformer is a device that uses two coils to convert voltage. These coils, known as the primary and secondary windings, determine the voltage conversion ratio.

There are various types of transformers, but oil-filled transformers are the most widely used in power supply applications.

Applications of Oil-Filled Transformers

Oil-filled transformers are used in numerous applications, especially in power transmission and distribution. Electricity produced in power plants is typically high voltage.

This high-voltage power is transmitted over towers and other structures to the transmission lines. Oil-filled transformers convert this high-voltage power for use in low-voltage distribution lines.

The transformed low-voltage power is then distributed to locations such as homes, factories, and commercial facilities. Oil-filled transformers at these sites adjust the voltage to levels suitable for local demands, such as 100 VAC or 200 VAC for households and 200 VAC or 400 VAC for industrial and commercial settings.

Principle of Oil-Filled Transformers

An oil-filled transformer comprises an iron core, coils, an oil tank, and insulating oil.

1. Iron Core

The iron core, situated at the transformer’s center, is constructed by laminating silicon steel plates and other materials to create a magnetic circuit. This multilayer structure reduces magnetic losses, enabling efficient power conversion.

2. Coil

The high-voltage and low-voltage windings are wrapped around the iron core. Made from copper or aluminum wire, these windings generate a magnetic field when current flows through them. In step-down transformers, the high-voltage side has fewer windings compared to the more numerous windings on the low-voltage side.

3. Oil Tank

The transformer’s components are enclosed within a steel tank, filled with insulating oil. This oil not only insulates the interior but also helps in cooling. Tanks often have fins to facilitate the circulation of the cooling oil and heat dissipation.

4. Insulating Oil

Mineral oil is commonly used as the insulating oil in oil-filled transformers. However, environmentally friendly alternatives like sunflower or rapeseed oil are also in use. These oils, while more expensive, help prevent environmental pollution in case of leaks. Monitoring the concentration of organic gases in the insulating oil helps assess transformer conditions. Overheating produces gases like ethylene and ethane, while partial discharge generates acetylene and hydrogen. Acetylene, especially, is an indicator of internal transformer abnormalities and should not be present even in trace amounts.

Types of Oil-Filled Transformers

Oil-filled transformers are categorized into self-cooled and forced-cooled types.

1. Self-Cooling Type

Self-cooled transformers use internal oil and a cooling system for natural heat dissipation. Radiators or similar devices attached to the tank aid in this process. They are commonly used in power transmission and distribution systems.

2. Forced Cooling Type

Forced-cooled transformers have a cooling system that actively circulates oil. This enhanced cooling method is suitable for high-load or high-temperature environments, often involving pumps or fans for oil circulation.

Other Information on Oil-Filled Transformers

1. Allowable Temperatures for Oil-Filled Transformers

Excessive heating in oil-filled transformers risks insulation failure and potential fires. Therefore, maintaining the operating temperature below the permissible limit is crucial. The general maximum allowable temperature is 105 °C, but it is typically controlled to remain around 95 °C or lower, considering external influences and temperature differences.

2. Treatment of Oil-Filled Transformers Under the Fire Service Law

Mineral oil in oil-filled transformers, usually classified as Petroleum No. 3, becomes a hazardous material under the Fire Service Law when the volume exceeds 2,000 liters. However, when connected to an electrical circuit, it falls under the Electricity Business Law and is not treated as a hazardous material. If disconnected from the power line, such as during dismantling, it reverts to being a hazardous material. Specific circumstances require consultation with the fire department or relevant authorities.

What Is a Water Meter?

A water meter is an instrument used to measure the flow rate of a liquid, a body, or any other mass or volume.

Also called a flowmeter, when selecting an instrument, the purpose of use should be clearly defined, and the accuracy, measurement range, and required sensors should be selected. High accuracy is not necessary for monitoring or controlling water volume but is required for controlling the amount of application or spraying.

There are two types of measurement methods: volume flow rate, which measures the change in volume per hour, and mass flow rate, which measures the change in mass per hour. Water volume control is important from the viewpoint of quality control, early detection of equipment malfunctions, protection of equipment, and cost reduction through understanding of water volume.

Uses of Water Meters

Water meter is used at plants and manufacturing sites to control the amount of water in piping facilities such as water supply and drainage pipes, etc. When installed outdoors, select a device that is compatible with outdoor environments or a device with a large bore that can handle higher flow rates and higher pressures.

Flow control of cooling water and cleaning water at metal processing and semiconductor manufacturing sites has become important from the viewpoint of quality control, and equipment can be selected in consideration of clogging, maintainability, and accuracy.

In the case of coating liquids and lubricating oil other than water, models that enable more precise flow control are selected from the viewpoint of process control. Other applications include manufacturing in the food, chemical, and paper industries.

Principle of Water Meters

The principle of a water meter depends on the measurement method.

1. Ultrasonic Flowmeter

Ultrasonic waves are transmitted and received from two points on the pipe, and the difference in propagation time is measured.

2. Electromagnetic Flowmeter

The electromagnetic flowmeter measures the amount of water by measuring the electromotive force generated by the movement of a conductive liquid in a magnetic field. Faraday’s law of electromagnetic induction is used as the measurement principle.

3. Area Type Flowmeter/Floater Type Flowmeter

The water volume is measured by the position of the float that moves up and down.

4. Coriolis Flowmeter

Water flows through a U-shaped pipe and the amount of water flow is measured by comparing the amount of twist in the pipe.

5. Kalman Vortex Flowmeter

When water passes through a column-shaped vortex generator, a vortex is generated, and the number of vortices is detected to measure the amount of water.

6. Impeller Type Flowmeter

Pulses generated by the turning of the impeller are converted into a voltage signal to measure the amount of water.

7. Differential Pressure Flowmeter / Orifice Flowmeter

This meter measures the amount of water by detecting the difference in pressure between the front and back sides of the water as it passes through the throttle valve. The square root of the differential pressure between two points is taken according to Bernoulli’s theorem, so the amount of water can be calculated accurately.

Types of Water Meters

There are a wide variety of water meter types, depending on the principle of measurement. Each method has different features, advantages, and disadvantages.

1. Ultrasonic Flowmeter

Installed on the outside of piping, ultrasonic flowmeters are used to measure outdoor piping. Since there are no moving parts, maintenance is easy, and digital and analog flowmeters can be used. However, it is prone to errors due to air bubbles.

2. Electromagnetic Flowmeter

Low-pressure drop and can measure the direction of flow.

3. Area Flowmeter/Floater Flowmeter

Simple structure and low cost, but not very accurate.

4. Coriolis Flowmeter

It is insensitive to changes in viscosity and density and has a fast response speed. However, it is expensive and has a large pressure drop.

5. Karman Vortex Flowmeter

Simple structure with no moving parts, but vulnerable to vibration.

6. Impeller Type Flowmeter

Used in large water meters.

7. Differential Pressure Flowmeter or Orifice Flowmeter

Simple, inexpensive, and easy to install and remove. On the other hand, they cause pressure loss and are not suitable for measuring liquids mixed with solids or small flow rates.

How to Select Water Meters

Since there are many types of water meters, it is necessary to select the right product for your purpose. First, define the purpose of the measurement and determine the accuracy required of the water meter. For example, volumetric flow monitoring displays instantaneous flow rates and does not require high accuracy. And if the error that causes an alert is too fine, on the contrary, it is because it is not useful.

Next, consider the detailed conditions of the actual installation environment. Specifically, the power supply, output signal, and installation location are important.

Finally, the cost is compared to determine the best solution. Not only the price of the main unit but also the price of related equipment, installation costs, maintenance work costs, etc. must be compared in total to make a decision.

What Is a Water Tester?

Water testers are water quality meters capable of evaluating multiple components simultaneously in a single measurement. The specific components that can be measured may vary depending on the instrument. These testers are designed for field use, built to withstand impact, and are easy to operate with one hand. While capabilities vary between devices, most water testers can measure fundamental water quality parameters such as pH, electrical conductivity, dissolved oxygen, and temperature. Multiple sensors are combined and connected to the main unit via a cord, and the measurement results are displayed on the main unit.

Uses of Water Testers

Water testers are employed to measure the constituents of river water, groundwater, and industrial wastewater. They are primarily intended for field use and practical applications. The sensor part and the main unit are connected via a connector, and the sensor is immersed directly into the water body or tank to be measured. Longer cables are available, allowing measurements while moving along the flow of a river or in deep lakes and marshes. Depending on the device, it can also be inserted directly into a pipe for measurements during a borehole survey, offering versatile applications based on the instrument’s capabilities.

Principle of Water Testers

Water testers employ different sensors and principles to measure various parameters. The key water quality measurement parameters that can be measured with water testers are described below.

1. pH

pH refers to the concentration of hydrogen ions and is a fundamental parameter in water quality measurement because it indicates the characteristics of the solution. pH sensors must be calibrated with a standard solution before use. Most water testers use a glass electrode method to measure pH.

2. Electrical Conductivity (EC)

Electrical conductivity (EC) expresses the ease with which electricity flows in a solution. The higher the concentration of substances dissolved in a solution, the greater its electrical conductivity. For instance, seawater, which contains dissolved salts, has a higher electrical conductivity. Since there is a constant relationship between conductivity and salinity, it is possible to determine salinity from conductivity and temperature.

3. Dissolved Oxygen (DO)

Living organisms in water rely on oxygen dissolved in the water for survival. Since the amount of dissolved oxygen varies depending on environmental factors such as temperature, it is used as a measurement parameter. Various measurement methods exist for dissolved oxygen, and sensors require regular maintenance.

What Is a Water Quality Sensor?

A water quality sensor is a sensor used to measure water quality.

Major measurement items include pH (hydrogen ion concentration), ORP (oxygen reduction potential), DO (dissolved oxygen), and EC (electrical conductivity), etc. Not only single-item measurement sensors but also combined sensors are available. In addition to these items, there are also a variety of products that can measure water temperature, water level, water pressure, salinity, ammonia, turbidity, and other parameters.

Uses of Water Quality Sensors

Water quality sensors are mainly used by research institutes to measure water quality in rivers, lakes, marshes, and oceans; in agriculture to manage hydroponics, liquid fertilizer, and agricultural wastewater; and in factories to control wastewater.

In addition to surface water and groundwater measurements, the system also plays an important role in water quality inspections at aquaculture farms, where accurate water quality control is required. Water quality sensors are also used in the quality control of grey water, which is sometimes referred to as recycled water after it has been used for drinking water treatment.

Principle of Water Quality Sensors

Water quality sensors mainly measure pH (hydrogen ion concentration), ORP (oxygen reduction potential), DO (dissolved oxygen), and EC (electrical conductivity). Each of these items can be measured separately or as a combined sensor.

1. PH

pH is the concentration of hydrogen ions. The glass electrode method is mainly used as the measurement method. The glass electrode method uses a glass electrode and a reference electrode to determine pH by measuring the potential difference (voltage) generated between the two electrodes.

River water generally has a pH of around 7, but since it varies depending on the location and conditions, it is considered a major parameter in water quality surveys.

2. ORP

ORP is the oxygen reduction potential. It is an indicator of the oxidizing or reducing potential of water and represents the potential determined by the balance between dissolved oxidized and reduced substances.

The measurement method is similar to that of pH measurement, using a pH meter body with an mV measurement function, a precious metal electrode (platinum or gold electrode), and a comparison electrode.

3. DO

DO refers to dissolved oxygen. Dissolved oxygen indicates the amount of oxygen dissolved in water quality, a value that varies with temperature, salinity, and atmospheric pressure. Since living organisms in water consume the oxygen dissolved in the water to survive, it is used as one indicator of the ease of survival of living organisms.

Specific measurement methods include the titration method, diaphragm electrode method, and fluorescence method. In the fluorescence sensor, fluorescence is irradiated onto the sample, and the concentration of dissolved oxygen is calculated from the attenuation of transmitted light using the phenomenon of quenching by dissolved oxygen. In other words, the higher the concentration of dissolved oxygen, the stronger the quenching phenomenon and the lower the fluorescence detected by the detector.

4. EC

EC is the electrical conductivity. Electrical conductivity is an indicator of the ease of conducting electricity in water. It is measured by passing electricity between electrodes immersed in a solution.

Pure water does not conduct electricity, but solutions with high levels of electrolytes in the water conduct electricity easily. An example of an electrolyte in water is nitrogen dissolved in wastewater.

Types of Water Quality Sensors

There are two types of water quality sensors: those that are installed according to the application and portable types that can be carried around. The portable type consists of a stick-shaped sensor and an operating unit, such as an instrument monitor, connected by a cable.

The electrode is placed in the water and the values are read from the panel on the main unit. Because of the risk of dropping the device when used outdoors or in the field, many products are designed to be robust and easy to operate even with one hand. Also available are models that are highly adaptable to heat and have been developed to enable measurement in places with extreme temperature fluctuations.

What Is a Water Pressure Gauge?

A water pressure gauge is a device designed to measure the pressure of fluids, such as water, flowing inside a water pipe. It is typically connected to a branch of a water pipe, allowing the measurement of the fluid’s pressure within the pipe. Water pressure gauges find applications in various scenarios, including civil engineering works, the installation of toilets, and water pipe systems. There are both mechanical and electronic water pressure gauges available, with some capable of storing measurement data for several hours.

Uses of Water Pressure Gauges

Water pressure gauges are employed in the construction of houses and factories that utilize fluids. They serve a variety of specific purposes, including the inspection of pipes in toilets, water supply systems, and drainage systems in civil engineering projects. Water pressure gauges are also crucial for inspecting water supply facilities during factory startups and managing the water pressure of chemical solutions in industrial settings. When selecting a water pressure gauge, factors to consider include its pressure measurement range, compatibility with the type of fluid it will handle, characteristics such as pH tolerance, ease of maintenance, and connectivity with other equipment.

Principle of Water Pressure Gauges

The operation principle of water pressure gauges involves the use of a pressure sensor, a pipe joint for connection to a water pipe, and a display. The joint is typically designed as a screw, allowing it to be attached to a branch of a water pipe for pressure measurement. Digital water pressure gauges may store data collected from the sensor in memory or transmit it to other devices, often serving as switches for other equipment.

During operation, the water pressure is measured using a pressure sensor. The specific type of pressure being measured is static pressure, which can be obtained by installing the measuring section perpendicular to the direction of water flow within the pipe. The pressure sensor itself comprises a piezoelectric element that deforms in response to pressure changes, generating an electrical signal that represents the pressure measurement. When measuring water pressure in a water pipe, it’s important to perform the measurement while water is flowing, as the specified water pressure must be maintained during water drainage. In such cases, the water pressure may be lower compared to when water is not draining, so attention to detail is necessary.

What Is a Moisture Meter?

A moisture meter is an instrument that measures the amount of moisture contained in a material. These devices can measure moisture in gaseous, liquid, and solid states. Moisture meters can be classified based on their application: dry, Karl Fischer, infrared absorption, and dielectric constant, among others. The dry and Karl Fischer moisture meters are commonly used in laboratory settings.

Moisture meters are also categorized by their specific applications, used for measuring moisture content in various materials such as food, soil, concrete, and more. Some moisture meters are designed to comply with official standards, such as ISO, for measuring moisture content in food products.

Uses of Moisture Meters

Moisture meters find applications in a wide range of industries for measuring the moisture content of different materials, including food products, industrial goods, and wood. The choice of moisture meter and measurement procedures must be tailored to each specific product due to variations in shape, moisture content, control values, and other factors.

In the food industry, moisture meters employing the drying method are used for products like rice and wheat. These meters include a balance and dryer for precise measurements. For other food industry applications, such as miso and oil, the Karl Fischer method is commonly employed. The Karl Fischer method is also utilized by material manufacturers dealing with substances that dissolve in organic solvents.

Soil moisture measurements use moisture meters based on the tensiometer method, while high-frequency capacitance moisture meters are used for measuring concrete moisture content.

Principle of Moisture Meters

Moisture meter measurement methods vary significantly based on the specific technique employed. These methods include:

1. Drying Method

Figure 1. Principle of the drying method

The drying method is a straightforward technique where the mass of the sample is measured before and after drying in a thermostatic oven heated to around 100°C for approximately 3 hours. The change in mass is used to estimate the moisture content. Some moisture meters combine a dryer and a precision balance for controlled temperature and time measurements. The drying method is often the official testing method for grains and other food products.

2. The Karl Fischer Method

Figure 2. Karl Fischer method reaction equation

The Karl Fischer moisture meter quantifies water content through a chemical reaction with sulfur dioxide, iodine, low-carbon alcohol (e.g., methanol), and an organic base such as pyridine. The coulometric titration method, based on the consumption of iodine generated from iodide ions at the anode, is commonly used to measure moisture content. Substances with reducing properties like ascorbic acid cannot be measured with the Karl Fischer method as they consume iodine through a different chemical reaction.

3. Tensiometer

Figure 3. How the tensiometer works

The tensiometer is a technique for measuring soil moisture. It features a porous cup attached to a pipe, filled with water, and inserted into the soil. Pressure changes are monitored to determine the amount of moisture that has penetrated the soil. However, the tensiometer may not provide highly accurate measurements in dry soil due to the formation of gaps.

4. Capacitance Method

This method measures water content in materials like soil, concrete, or other materials whose relative permittivity is sufficiently small compared to water. A sample is placed between two electrodes, and capacitance changes are measured by applying a voltage. Recent advancements have improved the accuracy of this method, making it suitable for use at construction sites.

Other Information on Moisture Meters

Points to Note When Using Moisture Meters

Moisture is present in substances like air, so it’s essential to consider the measurement environment when using moisture meters. When measuring trace amounts of moisture, variations in laboratory humidity or the time the sample is exposed to the atmosphere can affect measurements.

For Karl Fischer methods, ensuring that joints are tightly sealed to prevent moisture from entering through pipe joints is critical. Moisture in inert gases like nitrogen used during measurements must be removed beforehand using desiccants like silica gel.

What Is a Moisture Sensor?

Moisture sensors are sensors used in a wide range of fields to measure the amount of moisture in wood, coal, food, fiber, and other materials.

The measurement methods used include electric capacitance, electric resistance, microwave, near-infrared, and neutron. Electricity, neutrons, and near-infrared rays are applied to the object to be measured, and the moisture sensor detects and determines the amount of moisture.

Although it depends on the method, there are two main types: those that directly contact the sample for measurement and those that allow non-contact measurement.

Applications of Moisture Sensors

As mentioned above, moisture sensors are used to measure the moisture content of various materials and are utilized by manufacturers and factories to measure the moisture content of wood, paper, coal, food, fiber, and other materials. It is often used to check the quality of products before they are shipped.

Soil moisture sensors are especially used to check the amount of moisture necessary for the growth of agricultural crops. They are also sometimes used by cosmetics manufacturers to measure the moisture content of skin.

Moisture sensors can thus be used to measure the moisture content of various materials, but it is important to select the right sensor and model for the application and object.

Principles of Moisture Sensors

The main measurement methods include the following

1. Electric Capacitance Type

In the electric capacitance method, an alternating current is applied to the measurement target from an electrode, and the change in capacitance, or electrical capacitance, is converted into the amount of moisture. In the oscillation circuit, which is the detection circuit, the change in electrode capacitance causes the oscillation frequency to change.

The larger and thicker the object being measured, the greater the change in electrode capacitance. The advantage of this method is that it is easy to miniaturize and does not damage the object to be measured. Since it is affected by thickness and density, it is necessary to measure under the same conditions.

2. Electrical Resistance Type

Moisture sensors of the electrical resistance type conduct electricity to the object to be measured and convert its resistance value into the amount of moisture. Since it is not easily affected by the density of the object to be measured, it is suitable for measuring objects whose density easily changes.

3. Microwave Type

This method measures the moisture content based on the attenuation of microwaves, a type of electromagnetic wave when they are irradiated onto the object to be measured. It can quickly measure the moisture contained inside the object but requires the installation of a large device.

4. Near-Infrared Type

Near-infrared rays are light with wavelengths longer than visible light and outside of red. Near-infrared moisture sensors irradiate near-infrared rays, which are light with wavelengths longer than visible light and outside of red, to the object being measured. Since moisture absorbs near-infrared light well, the greater the moisture content, the less light is reflected. Using this principle, the amount of moisture is determined from the reflectance of the irradiated near-infrared light.

The advantage of this method is that it is easy to install and does not damage the object to be measured. The disadvantages are that only a small portion of the surface can be measured and that it is affected by the color of the object being measured. Wide-area irradiation type, fiber type, and other forms are available.

5. Neutron Type

Neutron-type instruments use a source of neutrons, a type of radiation. Fast neutrons lose energy when they repeatedly collide with hydrogen atoms and are transformed into slow thermal neutrons. In other words, the amount of fast neutrons converted to thermal neutrons is proportional to the amount of hydrogen, so it is possible to calculate water content using a neutron source that emits fast neutrons and a detector sensitive to thermal neutrons.

This method can also measure the water content inside. On the other hand, it should be noted that the equipment has a short life span and is fragile. Also, since it handles radiation, it requires specialized knowledge.

6. Dry Weight Loss Method

In the loss-on-drying method, a sample of the measured material is taken and dried using a convection dryer or a heat source (halogen lamp, microwave, etc.), and the moisture content is determined from the weight of the sample before and after drying. This method is said to be highly accurate, but it should be noted that sample collection is required and that this is not a nondestructive test.

Types of Moisture Sensors

Moisture sensors, as mentioned above, use a variety of principles. Many of the actual products, such as “Soil Moisture Sensors” and “Concrete and Mortar Moisture Sensors,” have limited applications envisioned in advance and should be selected according to the intended use.

In addition, there are a variety of shapes and sizes, from tabletop and portable machines to relatively large machines, so there is a wide range of types to choose from depending on the situation in which they are used.

What Is a Gas Flowmeter?

A gas flowmeter is an instrument designed to measure the quantity of gas flowing through a pipe or other equipment.

There exists a wide variety of gas flowmeters, each employing different principles of measurement, structures, and applications. These flowmeters are used to measure gas flow rates across various industries.

Gas flowmeters come in different types, including electronic flowmeters with digital displays, mechanical flowmeters with analog displays, and sensors that provide electrical signals without a visual display. Recent advancements have also introduced non-contact types of flowmeters that are suitable for high-temperature and corrosive gas measurements, as they do not make direct contact with the fluid.

Applications of Gas Flowmeters

Gas flowmeters find extensive use in various industrial sectors for measuring the rate of gas flow within pipes and specific structures. While their presence in everyday life is limited, residential gas meters are installed in households to measure gas consumption. In industrial settings, these flowmeters are essential for controlling gaseous fluid processes and managing gas distribution volume.

It’s important to note that gas flowmeters primarily measure the volume of gas in circulation, and there are also flow controllers available with additional flow control functionalities.

Principles of Gas Flowmeters

Gas flowmeters operate on diverse measurement principles, each suited for specific gas properties, temperature ranges, measurement ranges, and additional specifications. They can be broadly categorized based on their measurement principles:

1. Ultrasonic Type

The ultrasonic method is a modern and widely used measurement technique. It enables non-contact measurement, making it suitable for high-temperature or corrosive gases. Ultrasonic flowmeters employ sensors mounted externally to the piping and come in two main types: Doppler and transit time, which measure flow based on differences in wave propagation.

2. Coriolis Type

The Coriolis method, based on the Coriolis principle, excels at measuring mass flow rates with high accuracy. It can also calculate temperature, density, concentration, and volumetric flow rates based on the measurement results.

3. Thermal Type

The thermal method determines mass flow rates by placing a measuring unit with two heaters inside the gas and measuring the output difference resulting from heater cooling by the gas flow. This type allows for direct mass flow measurements. However, it requires contact with the fluid and may not be suitable for all gases due to potential impurity-related measurement deviations.

4. Differential Pressure Type

The differential pressure method is based on Bernoulli’s theorem and is a cost-effective measurement approach. It typically requires an orifice, which can lead to substantial pressure drops. Accuracy may be compromised if the gas flow velocity distribution in the channel is uneven.

What Is a Water Barrier

A water barrier is a material that prevents water from entering a building.

Water barriers can be broadly classified into two types: those used in civil engineering and construction, and those used to prevent flooding in buildings. Water barriers are used in civil engineering and construction, and are placed at the joints of concrete structures. They are used in the construction of underground buildings and civil engineering works for dams, tunnels, and elevated bridges.

Water barriers used to protect buildings from flooding are used to protect houses and other structures from flooding caused by heavy rains, such as typhoons and guerrilla rains. Water barriers of this type come in a variety of sizes, from small-scale ones for ordinary houses to large-scale ones for preventing rivers from overflowing.

Uses of Water Barriers

Water barriers are broadly classified into two types: water barriers for civil engineering and construction materials and water barriers used to prevent flooding of buildings and other structures.

1. Water Barriers for Civil Engineering and Construction Materials

Water barriers for civil engineering and construction materials are placed at the joints of concrete structures. When concrete structures are built, concrete is first poured as the foundation, and then concrete is poured again after the concrete has dried, a process known as jointing.

Water barriers are placed at the joints. They are used for concrete structures in various environments where water is generated, such as underground buildings, dams, tunnels, and seawalls.

2. Water Barriers Used for Flood Control in Buildings, etc.

Water barriers used to prevent flooding in buildings and other structures are placed in locations where water tends to penetrate to prevent flooding. Specific locations include subway entrances and exits, store entrances and exits, building and apartment entrances, and underground parking lots. Water barriers used to prevent flooding are also used on a large scale to prevent flood damage by being placed in areas where there is a high possibility of river flooding.

Principle of Water Barriers

The principle of water barriers varies depending on the type.

1. Water Barriers for Civil Engineering and Construction Materials

Water barriers for civil engineering and construction materials are placed at concrete joints. At joints, the concrete foundation, which is already dry, and the newly placed concrete do not mix, and a joint is formed between them. Since water can seep through these joints, a jointing process is used to fill the joints.

A common method is to use metal water barriers for this joint treatment. Water barriers are placed at the joints before the concrete is poured. The metal water barrier protrudes vertically from the surface of the concrete foundation and penetrates the concrete to be placed next. Water barriers prevent water from entering the joint between the two.

2. Water Barrier Used for Flood Control in Buildings, Etc.

Water barriers used to prevent flooding in buildings are placed at the entrances of buildings to prevent flooding. Lightweight and sturdy aluminum plates are used for this purpose.

Types of Water Barriers

This section describes the types of water barriers used to prevent flooding of buildings and other structures. The main types include door type, motorized type, manual type, sliding type, swinging type, and removable type.

1. Door Type

As the name suggests, the water barrier is shaped like a door.

2. Motorized Type

This type of water barrier is normally stored inside buildings, etc., and is electrically activated to stop water when in operation.

3. Manual Type

The manual type has the same shape as the electric type, but the installation is done by hand.

4. Sliding Type

In the sliding type, the water barrier moves horizontally, while in the swing type, it has a vertical axis of rotation and pivots to move the water barrier into position.

5. Detachable Type

The detachable type can be removed and installed only when necessary. It requires storage space but has advantages such as low cost and almost no maintenance.

Other Information on Water Barriers

Use of Water Barriers

In recent years, houses and other structures have frequently been flooded by typhoons, torrential rains, and other sudden disasters. In light of this situation, information on flood prevention measures that can be taken at home has been disseminated mainly by local governments, and water barriers for home use have been attracting attention. Water barriers for home use are effective in the form of longboards of furniture such as tables, which are installed and secured at the entrances and exits of houses and buildings.

In this case, the width of the board should cover the entire width of the doorway and the height of the board should be adjusted to about knee-high. The board must be securely fastened so that it will not move. Waterbags, blocks, polyethylene tanks, stepladders, etc. can be used to secure the boards in place. Water barriers can also be improved by wrapping the board and the fixing material in a blue sheet and using the entire sheet as a water barrier.

Various other water barriers that can be used at home are available from various manufacturers. Water barriers available on the market come in a variety of shapes and sizes, depending on where they are to be installed. For example, some have a structure that can be easily attached to the sash frame of a house, allowing for quick installation work.