Lost your password? Please enter your email address. You will receive a link and will create a new password via email.
Please briefly explain why you feel this question should be reported.
Please briefly explain why you feel this answer should be reported.
Please briefly explain why you feel this user should be reported.
Of the Members, By the Members, For the Members!
VacuumFurnaces.com is a Q&A community where vacuum furnace product and service suppliers connect with commercial and captive heat treaters to share their practical skills and know-how and to establish valuable relationships around niche topics of expertise with vacuum furnace end-users in operations, production, training, maintenance, marketing, sales, and engineering.
How to improve the shelf life of an o-ring?
The specific steps needed to improve the shelf life of an O-ring can vary depending on the O-ring material and the conditions it will be subjected to. Always refer to the manufacturer's recommendations for the best results. Improving the shelf life of an O-ring involves several best practices in stoRead more
The specific steps needed to improve the shelf life of an O-ring can vary depending on the O-ring material and the conditions it will be subjected to. Always refer to the manufacturer’s recommendations for the best results.
Improving the shelf life of an O-ring involves several best practices in storage and handling:
Material Selection: The choice of material for an O-ring is crucial as some materials degrade more quickly than others when exposed to certain environments or chemicals. Make sure to select a material that is compatible with the intended use.
Storage Conditions: O-rings should be stored in a cool, dark, and dry place. UV light can degrade many materials used for O-rings. O-rings should also be kept away from electric motors and other sources of ozone, which can cause rapid deterioration.
Proper Lubrication: When in use, proper lubrication can reduce wear and tear, thereby extending the effective life of an O-ring.
Protective Packaging: O-rings should be kept in sealed bags with a neutral gas like nitrogen, if possible, to prevent oxidation and other atmospheric damage.
Controlled Environment: Temperature and humidity should be controlled. Extreme temperatures and high humidity can accelerate the degradation of O-ring materials. Itβs best to maintain a consistent and moderate environment.
Regular Inspection: Regularly inspect stored O-rings for signs of degradation, such as cracking, discoloration, or changes in texture.
Avoid Deformation: Store O-rings laid flat or hanging without tension, if possible, to avoid permanent deformation. O-rings that are deformed for an extended period may not function properly when used.
Cleanliness: Ensure that O-rings are clean before storage, as contaminants can cause degradation. They should be handled with clean gloves to avoid transferring oils or other contaminants.
Inventory Management: Use a first-in, first-out inventory system to ensure that O-rings are used in the order they are received, preventing old stock from becoming unusable.
Avoid Contact with Metals: Some metals can catalyze degradation. O-rings should not be stored in contact with metals, particularly copper or brass.
See lessHow to avoid backstreaming of diffusion pump oil?
Backstreaming of diffusion pump oil is a concern in vacuum systems where a diffusion pump is used to achieve high vacuum. Backstreaming is the process where the pump oil flows back into the vacuum chamber, which can contaminate the chamber and the processes taking place within it. Here are some geneRead more
Backstreaming of diffusion pump oil is a concern in vacuum systems where a diffusion pump is used to achieve high vacuum. Backstreaming is the process where the pump oil flows back into the vacuum chamber, which can contaminate the chamber and the processes taking place within it. Here are some general tips on how to avoid backstreaming of diffusion pump oil:
1. Use Baffles: Cold traps or baffles can be installed between the diffusion pump and the vacuum chamber to condense and trap the oil vapors.
2. Proper Pump Operation: Ensure that the diffusion pump is operated within its proper temperature range. Overheating can increase the vapor pressure of the oil, leading to backstreaming.
3. Maintenance: Regular maintenance of the pump, including checking for and repairing leaks, can prevent oil backstreaming.
4. Quality of Oil: Use high-quality, low-vapor-pressure diffusion pump oils designed for the specific type of diffusion pump being used.
5. Backing Pumps: The backing pump should be adequately sized and capable of reaching a low enough pressure to prevent oil vapors from traveling upstream.
6. Positioning: Orient the pump so that the oil is less likely to flow back into the chamber if the pump is turned off.
7. Isolation Valves: Install isolation valves that can be closed when the pump is not in operation to prevent oil from traveling back to the chamber.
8. Nitrogen Purge: A nitrogen purge system can be used to create a positive pressure that helps prevent oil vapors from backstreaming.
9. Check Valves: These can be installed to allow flow in one direction only, preventing backstreaming.
Each vacuum system may have specific needs, so it is essential to consult the diffusion pump’s manual or a vacuum technology specialist for guidance tailored to your particular setup. If you are dealing with a technical issue or system design, it might be helpful to review the documentation for your specific equipment or contact the manufacturer for advice.
See lessHow far can a thermocouple be placed inside the vacuum furnace?
For the exact placement of the thermocouple, you need to consult the vacuum furnaceβs manual or technical specs, as well as the datasheet for the specific thermocouple you are using. If you are unsure, it is advisable to consult with an engineer or a professional who specializes in thermal systems.Read more
For the exact placement of the thermocouple, you need to consult the vacuum furnaceβs manual or technical specs, as well as the datasheet for the specific thermocouple you are using. If you are unsure, it is advisable to consult with an engineer or a professional who specializes in thermal systems.
The placement of a thermocouple inside a furnace, including a vacuum furnace, typically depends on several factors:
1. Type of Thermocouple: Thermocouples have different temperature ranges and environmental constraints. High-temperature thermocouples are generally designed to withstand the harsh environments inside a furnace.
2. Furnace Type: Furnaces have different designs and may have specific requirements or limitations for thermocouple placement.
3. Measurement Needs: Thermocouple placement might be dictated by the areas where temperature readings are most critical. For example, you might place it in the center of the chamber for ambient temperature readings or closer to the heat source for more accurate readings of the source temperature.
4. Manufacturerβs Instructions: Always refer to the manufacturerβs guidelines for recommended placement, as they have designed the thermocouple to function optimally within certain conditions and parameters.
5. Safety: It’s important to ensure that the thermocouple does not touch any components inside the furnace, as this could affect the temperature reading or damage the furnace or the thermocouple.
See lessWhy are soaking periods of steel important in vacuum heat treating?
The heating process takes time, and once the metal has reached the desired temperature, it is maintained for a specific period of time. This is called the soaking period, which allows the metal to reach a uniform temperature throughout. Ensuring that the steel is held at the target temperature for tRead more
The heating process takes time, and once the metal has reached the desired temperature, it is maintained for a specific period of time. This is called the soaking period, which allows the metal to reach a uniform temperature throughout. Ensuring that the steel is held at the target temperature for the correct amount of time during the soaking period is key to successful heat treatment and the overall quality of the final product.
Soaking periods during the vacuum heat treating of steel are critically important for a few reasons:
1. Temperature Uniformity: Soaking is necessary to ensure that the entire workload reaches a uniform temperature. In vacuum heat treatment, the steel is heated by conduction and radiation within the chamber. Without a proper soak time, there might be temperature gradients within the material, meaning some areas could be hotter or cooler than others.
2. Stress Relief: Soaking at high temperatures also serves to relieve stresses within the material. This is important to avoid warping or distortion during cooling.
3. Transformation Completion: Steel has various microstructures that change with heat treatment. The soaking period allows for the complete transformation of these structures. For example, it allows carbon and other alloying elements to dissolve into the solid solution fully before quenching, which is essential for hardening processes like martensitic transformation.
4. Improved Properties: For certain steel grades, such as tool steels or high-speed steels, the soaking period can help in achieving desired mechanical properties such as hardness, toughness, and wear resistance by allowing for a more homogenous distribution of carbides and other precipitates within the steel matrix.
5. Gas Removal: Vacuum treatment is often used to avoid oxidation and to remove gases that might create porosity in the metal. Soaking ensures that gases are adequately removed from the surface and interior of the steel.
6. Process Control: In vacuum heat treating, process control is vital, and soak time is a parameter that can be precisely controlled to achieve the desired material properties. The ability to replicate the process accurately with controlled soak times is essential for consistent quality in treated steel products.
See lessHow does a Residual Gas Analyzer (RGA) work?
A residual gas analyzer (RGA) is a type of mass spectrometer used primarily to identify and quantify the gases present in a vacuum system. It allows for the analysis of gas species in the low-pressure environments often required in high-tech industries such as semiconductor manufacturing and surfaceRead more
A residual gas analyzer (RGA) is a type of mass spectrometer used primarily to identify and quantify the gases present in a vacuum system. It allows for the analysis of gas species in the low-pressure environments often required in high-tech industries such as semiconductor manufacturing and surface science. Here is a simplified description of how an RGA works:
Ionization of Gas Molecules:Β Gas molecules within the RGA’s sampling volume are ionized, usually by electron impact. This means that electrons are fired at the gas molecules by an electron gun, knocking off an electron and creating positively charged ions.
Mass Analysis:Β The ions are then directed into a mass filter, which is often a quadrupole mass filter. A quadrupole consists of four parallel metal rods, with each opposing rod pair connected to a radio frequency (RF) voltage with a direct current (DC) offset. The RF and DC fields are applied to the rods in such a way that only ions of a specific mass-to-charge ratio (m/z) can pass through the filter at any one time, with other ions being deflected and lost. By scanning through a range of RF and DC settings, ions of different m/z can be selectively filtered through the quadrupole, allowing the RGA to scan across a range of masses and thus detect multiple gas species.
Detection of Ions:Β The ions that pass through the mass filter reach a detector, which is often a Faraday cup or a secondary electron multiplier (SEM). These devices generate a signal proportional to the number of ions hitting them. The detector’s output is then processed and read out as a mass spectrum. Peaks on the spectrum correspond to the m/z of the ions, which can be used to identify the gas species. The height or area of the peak is proportional to the concentration of that species in the gas mixture.
Data Interpretation:Β The resulting data are interpreted to determine the types and quantities of gases present in the vacuum system. RGAs are crucial for quality control and system maintenance in vacuum systems, as they help identify contaminants, leaks, and outgassing sources which may compromise the integrity of the vacuum environment or the processes occurring within it.
For a more detailed explanation visit: Residual Gas Analysers – VAC AERO International
See lessHow do vacuum furnace heating elements fail?
Vacuum furnace heating elements can fail for several reasons related to material properties and operational conditions. Here are some common modes of failure: 1. Overheating: If the temperature exceeds the design limit of the heating elements, this can lead to rapid degradation and failure. 2. ElectRead more
Vacuum furnace heating elements can fail for several reasons related to material properties and operational conditions. Here are some common modes of failure:
1. Overheating: If the temperature exceeds the design limit of the heating elements, this can lead to rapid degradation and failure.
2. Electrical Overload: If the current exceeds the capacity of the heating elements, it can cause rapid heating and potentially melt or burn out the element.
3. Mechanical Damage: Accidental bumps, drops, and improper handling can cause cracks or breaks in brittle heating elements.
4. Thermal Stress: Repeated heating and cooling cycles can cause expansion and contraction of the heating element, which can lead to material fatigue and cracking over time.
5. Electromigration: At higher temperatures, atoms in the heating elements can move in response to the electric current flowing through them, leading to thinning and eventual breakage of the element.
6. Chemical Degradation: Even in a vacuum, elements can react with residual gases or impurities, which can lead to corrosion or the formation of brittle compounds on the element surfaces.
7. Evaporation: Elements like tungsten can slowly evaporate at high temperatures, which can thin the element and eventually cause it to fail.
8. Creep: At high temperatures, materials can slowly deform under mechanical stress, leading to sagging or distortion of the heating element shape, potentially causing short circuits or mechanical failure.
9. Contamination: The introduction of foreign materials can lead to hot spots, which can cause localized overheating and failure.
10. Design Flaws: If the heating elements are not properly designed for the specific application, including shape, size, or material choice, they can fail prematurely due to inadequate heat distribution or inability to withstand the thermal environment.
To prevent these failures, itβs important to maintain a clean vacuum environment, use materials that are appropriate for the operational temperature and atmosphere, ensure a proper design that accounts for thermal expansion, and avoid rapid temperature changes that can induce thermal stress. Regular maintenance and inspection can also help identify early signs of wear or failure in heating elements.
See lessWhat are some of the key advantages of bottom-loading vacuum furnaces?
Bottom-loading vacuum furnaces offer several advantages over other types of vacuum furnaces, such as top-loading or front-loading furnaces. These advantages make them particularly well-suited for specific applications in aerospace, automotive, and other high-tech industries. Here are some of the keyRead more
Bottom-loading vacuum furnaces offer several advantages over other types of vacuum furnaces, such as top-loading or front-loading furnaces. These advantages make them particularly well-suited for specific applications in aerospace, automotive, and other high-tech industries.
Here are some of the key advantages of bottom-loading vacuum furnaces:
1. Easy Loading and Unloading:
Bottom-loading furnaces are designed with a hinged or tilting door at the bottom of the chamber for easy loading and unloading of heavy or delicate workpieces. The materials can be placed on a platform or a tray that is lowered into the furnace chamber from the bottom. This eliminates the need for complex mechanical handling systems, making the loading and unloading process more efficient and thus reducing the risk of damage to the parts.
2. Enhanced Safety:
Bottom-loading vacuum furnaces provide enhanced safety for operators. Since the hot zone is located at the bottom, this reduces the potential for workplace accidents and ensures the safety of the operators. Additionally, the door design typically ensures a tight seal, minimizing the risk of vacuum leaks.
3. Energy Efficiency:
Since the heating elements and insulation are located at the top of the chamber, heat is less likely to escape during operation, which can result in lower energy consumption and faster heating and cooling cycles.
4. Better Temperature Uniformity:
Bottom-loading furnaces can provide more uniform temperature distribution within the chamber, as the heating elements are positioned at the top. This ensures consistent heat treatment across the entire workpiece, resulting in improved product quality and uniform properties.
5. Versatility & Flexibility:
Bottom-loading vacuum furnaces can accommodate a wide range of material sizes and shapes or irregularly shaped materials that may not be suitable for other types of furnaces. Their versatility makes bottom-loading furnaces suitable for a wide range of heat treatment processes and applications across different industries.
6. Improved Accessibility:
Bottom-loading furnaces provide better access to the furnace chamber, allowing for easier maintenance, cleaning, and part manipulation. This accessibility can lead to reduced downtime for maintenance and repairs.
7. Enhanced Cooling Options:
Many bottom-loading vacuum furnaces offer flexible cooling options, such as gas quenching or liquid cooling, which can be tailored to specific heat treatment processes. This capability allows for precise control over cooling rates and the achievement of desired material properties.
8. Improved Heat Distribution:
The bottom-loading design of the furnace chamber allows for improved heat distribution during the heating and cooling cycles. The heating elements are typically located at the top, bottom, and sides of the chamber, ensuring uniform heating of the materials. This results in better temperature control and more consistent heat treatment processes.
9. Reduced Footprint:
Bottom-loading furnaces often have a more compact footprint compared to top-loading or front-loading models, making them suitable for facilities with limited space.
10. Reduced Contamination:
Bottom-loading furnaces minimize the risk of contamination during the loading and unloading process. The materials being processed are not exposed to the overhead environment, which may contain airborne contaminants. This helps maintain the purity and quality of the processed materials, especially in applications where cleanliness is critical, such as in semiconductor manufacturing or aerospace industries.
While bottom-loading vacuum furnaces have numerous advantages, it is important to note that the advantages of a bottom-loading vacuum furnace may vary depending on the specific design and features of the furnace. Therefore, it’s essential to choose the right type of furnace for your specific application and requirements. Factors such as the size and shape of your workpieces, desired temperature range, and process control features should all be considered when selecting the most appropriate vacuum furnace design.
It is also recommended to consult with manufacturers or experts in vacuum furnace technology to determine the most suitable type of furnace for your specific application.
What are the leading Batch Vacuum Furnace Manufacturers (OEMs) worldwide?
See lessHow to size a vacuum booster pump for a vacuum chamber?
Sizing a vacuum booster pump for a vacuum chamber involves considering several key parameters and considerations to ensure that the pump can meet the vacuum requirements of the chamber. The size and capacity of the booster pump you need will depend on the specific characteristics of your vacuum systRead more
Sizing a vacuum booster pump for a vacuum chamber involves considering several key parameters and considerations to ensure that the pump can meet the vacuum requirements of the chamber. The size and capacity of the booster pump you need will depend on the specific characteristics of your vacuum system, including the chamber size, desired vacuum level, and the rate at which you need to evacuate the chamber.
Here’s a general guideline to help you size a vacuum booster pump:
1. Volume of the Vacuum Chamber:
2. Desired Vacuum Level:
3. Pumping Speed:
4. Process Throughput:
5. Backing (Primary) Pump Capacity:
6. Account for Gas Load:
7. Choose the Right Booster Pump:
8. Cooling Requirements:
9. Consider Additional Factors:
Remember that sizing a vacuum system accurately is crucial for achieving the desired vacuum level and maintaining the integrity of your vacuum chamber and the processes within it. Consulting with vacuum technology experts and pump manufacturers can help provide guidance based on your specific requirements and can provide detailed specifications, performance curves, and recommendations based on the specific requirements of your application.
See lessWhat are the key working principles of fore vacuum pumps?
Fore vacuum pumps are defined as those which exhaust to atmospheric pressure. They are also required to support secondary pumps or to attain the initial conditions for their operation. There are two types of fore vacuum pumps: Dry-running backing pumps such as scroll, screw and diaphragm pumps. Oil-Read more
Fore vacuum pumps are defined as those which exhaust to atmospheric pressure. They are also required to support secondary pumps or to attain the initial conditions for their operation. There are two types of fore vacuum pumps:
In this article, weβll examine the key working principles of five (5) common fore vacuum pumps:
Source: Vacuum Science World
See lessHow do you properly conduct a Temperature Uniformity Survey (TUS)?
Ensuring that a furnace can perform repeatable and accurate cycles is a cornerstone of AMS2750E pyrometry specifications as well as Nadcap and CQI-9 standards. The best way to measure and test any furnace is through a temperature uniformity survey (TUS). These surveys are critically important, and wRead more
Ensuring that a furnace can perform repeatable and accurate cycles is a cornerstone of AMS2750E pyrometry specifications as well as Nadcap and CQI-9 standards. The best way to measure and test any furnace is through a temperature uniformity survey (TUS).
These surveys are critically important, and when working to meet a specification or standard, itβs critical to follow the requirements of that standard.
Source: Conrad Kacsik Instrument Systems Inc.
See lessWhat are the changes from AMS2750F to AMS2750G?
The changes from AMS2750F to AMS2750G include revisions and updates to the pyrometric requirements for equipment used in the thermal processing of metallic materials. The AMS2750G specification covers temperature sensors, instrumentation, thermal processing equipment, correction factors and instrumeRead more
The changes from AMS2750F to AMS2750G include revisions and updates to the pyrometric requirements for equipment used in the thermal processing of metallic materials. The AMS2750G specification covers temperature sensors, instrumentation, thermal processing equipment, correction factors and instrument offsets, system accuracy tests, and temperature uniformity surveys. These changes are necessary to ensure that parts or raw materials are heat treated in accordance with the applicable specifications. The purpose of AMS2750G is to ensure that parts or raw materials are heat treated in accordance with the applicable specifications.
The revision from AMS2750F to AMS2750G mainly consists of administrative changes rather than significant technical changes. One notable change is that digital recording instruments are not required to read to the tenth of a degree until one year after the release of AMS2750G. Additionally, over temperature controls have been given a permitted error within AMS2750G, which was not present in revision F.
To comply with AMS2750G, suppliers who already conform to AMS2750F should find the transition relatively straightforward. It is recommended to consult experts or training courses that specialize in AMS2750 standards and Nadcap requirements to ensure compliance. Calibration services and process certification services can also be helpful in meeting industry standards.
Some specific changes between AMS2750F and AMS2750G include:
Revision G marking: Historically, AMS2750 did not mark the revision when released using change bars, unlike other AMS specifications. However, when AMS2750F was revised to revision G, change bars were included. This makes it easier for suppliers to understand the modifications and account for those changes internally.
Extensive changes: AMS2750G is considered a complete rewrite of the specification, and there are no change bars to indicate specific changes. The changes are extensive and cover various aspects of pyrometry requirements.
It is important to refer to the official AMS2750G specification for a comprehensive understanding of all the changes and updates.
For more detailed information and updates on AMS2750G, you can visit the SAE International website or refer to the Conrad Kacsik blog post on the differences between AMS2750F and AMS2750G.
SOURCES:
Pyrometry AMS2750G – SAE International
Differences Between AMS2750F and AMS2750G – Conrad Kacsik
See lessHow do you achieve ultra-high vacuum levels?
In order to achieve ultra high vacuum conditions, special materials and pumping procedures are needed. Seals and gaskets used between components in a UHV system must prevent even trace leakage. Therefore, nearly all such seals are all metal, with knife-edges on both sides cutting into a soft gasket,Read more
In order to achieve ultra high vacuum conditions, special materials and pumping procedures are needed. Seals and gaskets used between components in a UHV system must prevent even trace leakage. Therefore, nearly all such seals are all metal, with knife-edges on both sides cutting into a soft gasket, typically copper. These all-metal seals can maintain integrity to UHV ranges.
Tips for achieving ultra-high pressure include:
Source: VAC AERO International – Pumps for High and Ultra-High Vacuum
See lessWhy is it important to use a clean and controlled environment in vacuum heat treatment?
Using a clean and controlled environment in vacuum heat treating is important for several reasons: 1. Contamination prevention: Vacuum heat treating involves subjecting materials to high temperatures in a controlled atmosphere. Any contaminants present in the environment can react with the materialRead more
Using a clean and controlled environment in vacuum heat treating is important for several reasons:
1. Contamination prevention:
Vacuum heat treating involves subjecting materials to high temperatures in a controlled atmosphere. Any contaminants present in the environment can react with the material or form unwanted surface layers, leading to discoloration or other quality issues. By maintaining a clean environment, the risk of contamination is minimized, ensuring the integrity of the heat-treated parts.
2. Consistent results:
A controlled environment helps in achieving consistent and repeatable results during the heat-treating process. Contaminants or impurities can introduce variability in the heat treatment process, leading to inconsistent outcomes. By eliminating or minimizing the presence of contaminants, the heat-treating process can be more predictable, resulting in consistent and reliable results.
3. Surface quality:
Cleanliness of the environment is crucial for achieving desired surface quality in heat-treated parts. Contaminants can cause surface imperfections, such as stains, discoloration, or pitting, which can affect the appearance and functionality of the parts. A clean environment helps maintain the desired surface finish and appearance of the heat-treated parts.
4. Material integrity:
Some materials are sensitive to contamination and can react with certain elements present in the environment. For example, reactive metals like titanium can easily react with oxygen, nitrogen, or carbon, leading to surface discoloration or degradation. By using a clean and controlled environment, the risk of such reactions can be minimized, preserving the integrity of the material.
5. Process efficiency:
A clean environment can contribute to the overall efficiency of the vacuum heat-treating process. Contaminants can interfere with heat transfer, affecting the uniformity of temperature distribution within the vacuum chamber. By ensuring a clean environment, heat can be transferred more efficiently, leading to faster and more effective heat treatment cycles.
In summary, using a clean and controlled environment in vacuum heat treating is essential to prevent contamination, achieve consistent results, maintain surface quality, preserve material integrity, and enhance process efficiency.
See lessWhat are the 5 signs of vacuum pump failure?
Even the most well-constructed vacuum pump can fail after extended use. In industrial applications, for instance, the downtime resulting from pump failures can be prohibitively expensive β especially if it forces production to grind to a halt. Knowing the signs of vacuum pump failure is crucial in mRead more
Even the most well-constructed vacuum pump can fail after extended use. In industrial applications, for instance, the downtime resulting from pump failures can be prohibitively expensive β especially if it forces production to grind to a halt.
Knowing the signs of vacuum pump failure is crucial in maintaining a functioning system and avoiding dangerous or expensive issues resulting from. Your maintenance plan should allow for the servicing, repair, and replacement of pumps. For smaller projects, this may involve sending pumps back to the manufacturer. With this in mind, here are the common signs of a failing vacuum pump:
Source: Vacuum Science World – What are the 5 signs of vacuum pump failure?
See lessWhat are the four basic rules for working under HV and UHV conditions?
When working with high vacuum (HV) and ultra-high vacuum (UHV), there are specific aspects to consider ensuring an efficient and safe system. To clarify, the pressure range of UHV conditions are defined as between 10-7 and 10-12 mbar, whereas HV conditions are defined as between 10-3 and 10-7 mbar.Read more
When working with high vacuum (HV) and ultra-high vacuum (UHV), there are specific aspects to consider ensuring an efficient and safe system.
To clarify, the pressure range of UHV conditions are defined as between 10-7 and 10-12 mbar, whereas HV conditions are defined as between 10-3 and 10-7 mbar. Some of the main applications of HV include metallurgical processes, nuclear physics, space simulation and analytical instruments. On the other hand, UHVs are used for surface analysis, in high-energy physics and Molecular Beam Epitaxy (MBE).
Here are the four main considerations you need to bear in mind when working under HV or UHV conditions.
Source: Vacuum Science World – Four basic rules for working under HV and UHV conditions.
See less