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Product Testing and Lab Applications
Vacuum chambers and components are specialized vessels that can maintain a high vacuum process environment. Depending upon their configuration and optional components or features, they can be used for a wide variety of product testing and lab applications in which a product or material is stressed and analyzed under specific atmospheric or environmental conditions.
Vacuum chambers, when combined with a variety or optional accessories, can be used for a wide variety of product tests in which atmospheric or environmental conditions must be simulated.
The following is a listing of examples of the variables that can be controlled and measured using Abbess Vacuum Chambers.
What can you control in a Vacuum Chamber?
- Pressure
- Temperature
- Humidity
- Atmosphere/ Altitude or pressure
- Electromagnetic Radiation
- Microwave Radiation
What Product features can you measure in a Vacuum Chamber?
- Leakage
- Rigid Packaging
- Flexible Packaging
- Packages with threaded or lug-style closures
- Packages with mechanical dispensing systems
- Filtration membranes/Reverse Osmosis devices
- Product integrity
- Flexible material seams
- Effects of altitude on packaging
- Gaskets
- Bond Strength
- Corrosion
- Contamination
- Hermeticity
- Porosity
- Permeability.
- Liquid permeability
- Gas permeability
- Difusion permeability
- Water vapor permeability
- Liquid permeability
- Absorption/Saturation Capacity
- Gettering Rates.
- Specific Gravity
- Vapor Pressure
- Density
- Deposition Rate/Film Thickness
- Specific Gravity
- Vapor Pressure
- Density
- Deposition Rate/Film Thickness
- Instrument Calibration
- Helium Leak detectors
- Thermocouples
- Volatility
- Total Mass Loss
- Collected Volatile Condensable Materials
- Total Mass Flux
- Emissions
- Acoustic
- Gaseous
- Electromagnetic EMI
| Descriptions: |
Product Testing and Lab Applications
Vacuum chambers and components are specialized vessels that can maintain a high vacuum process environment. Depending upon their configuration and optional components or features, they can be used for a wide variety of product testing and lab applications in which a product or material is stressed and analyzed under specific atmospheric or environmental conditions.Vacuum chambers, when combined with a variety or optional accessories, can be used for a wide variety of product tests in which atmospheric or environmental conditions must be simulated.
The following is a listing of examples of the variables that can be controlled and measured using Abbess Vacuum Chambers.
What can you control in a Vacuum Chamber?
- Pressure
- Temperature
- Humidity
- Atmosphere/ Altitude or pressure
- Electromagnetic Radiation
- Microwave Radiation
What Product features can you measure in a Vacuum Chamber?
- Leakage
– Rigid Packaging
– Flexible Packaging
– Packages with threaded or lug-style closures
– Packages with mechanical dispensing systems
– Filtration membranes/Reverse Osmosis devices - Product integrity
– Flexible material seams
– Effects of altitude on packaging
– Gaskets
– Bond Strength
– Corrosion
– Contamination - Hermeticity
- Porosity
- Permeability.
– Liquid permeability
– Gas permeability
– Difusion permeability
– Water vapor permeability
– Liquid permeability - Absorption/Saturation Capacity
- Gettering Rates.
- Specific Gravity
- Vapor Pressure
- Density
- Deposition Rate/Film Thickness
- Specific Gravity
- Vapor Pressure
- Density
- Deposition Rate/Film Thickness
- Instrument Calibration
– Helium Leak detectors
– Thermocouples - Volatility
– Total Mass Loss
– Collected Volatile Condensable Materials
– Total Mass Flux - Emissions
– Acoustic
– Gaseous
– Electromagnetic EMI
Altitude vs. Pressure, Temperature and Density see datasheet
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Vacuum Drying
Vacuum drying is the removal of liquid material from a solution or mixture under reduced air pressure, which results in drying at a lower temperature than is required at full pressure. Vacuum drying can be applied in a range of processes in several industries, including chemical, pharmaceutical, food, plastics, and metal powders to remove water and other chemicals or solvents through evaporation or sublimation. Vacuums alter vapor pressure to enhance evaporation rates as well as increase the drawing out of liquids in pastes by capillary pressure. The process is essentially a thermal process whereby heat is transferred to the material by conduction through the dryer’s heated surface. Often agitation and/or tumbling can be employed to enhance the drying process.
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Vacuum Degassing
Vacuum Degassing – The use of a vacuum technique to remove dissolved gases from various materials. Vacuum degassers remove atmospheric interferences and diffused gases from solvents, mobile phases, and reagents during use. Within these degassers, water trickles through the system where its flow is interrupted up by a packed filtration medium. The water flow is broken down into a very thin film, which allows gases to escape at an enhanced rate. An internal vacuum system inside the filter increases the rate at which gases can be extracted from the sample. Vacuum Degassing can be used for, but is not restricted to, the following materials: epoxies, urethanes, resins, silicone rubber, adhesive mixes, castings, plaster, compounds used in jewelry, sculptures, medical, electrical or non-metallic components.
IntroductionWhen material like those listed above are mixed, air bubbles become trapped within the mixture. If allowed to cure without removing these bubbles, defects such as hollows, cavities or nodules will be present in the finished casting. These defects may degrade the integrity of the end application immediately or may emerge after a period of use such as with electrical encapsulation whose components may fail over time.
The components of a mixture may be mixed by any appropriate means before degassing. However, for effective vacuum degassing to be performed, the mixture must be fluid i.e. able to be poured. The mixture can then be placed into the vacuum chamber, which will reduce the air pressure such that gas bubbles (i.e. air) which were initially formed at atmospheric pressure will expand and escape from the liquid’s surface. This released gas will then be pumped out of the vacuum chamber.
Deaeration of RTV Silicone Rubber Curing Agents
Air entrapped during mixing should be removed to eliminate voids in the cured product. Expose the mixed material to a vacuum of at least 22mm (29 in.) of mercury. The material will expand, crest and recede to about the original level as the bubbles break. Degassing is usually complete about two minutes after frothing ceases. When using RTV silicone rubber for potting, a step ( vacuum filling using a fill under vacuum option) may be necessary after pouring to avoid capturing air in complex assemblies. For vacuum chamber options call Abbess Instruments.
Automatic equipment designed to meter, mix, deaerate and dispense two-component RTV silicone rubber compounds will add convenience to continuous or large operations.
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Atmospheric Simulation
Atmospheric Simulation – Vacuum chambers can be used in a wide variety of product testing applications to simulate a variety of atmospheric conditions by controlling pressure (altitude), temperature, and/or humidity.
Vacuum Impregnation
Altitude vs. Pressure, Temperature and Density
This table gives density in slugs per cubic foot because it uses the American system of altitude in feet, pressure in inches of mercury and temperature in degrees Fahrenheit. While people often use pounds per cubic foot as a measure of density in the U.S., pounds are really a measure of force, not mass. Slugs are the correct measure of mass. You can multiply slugs by 32.2 for a rough value in pounds.
Pressure is given in inches Hg Absolute. Subtract inches HgA from 29.92 for gauge readings (in. HgV)
Altitude Equivalent Pressure
- 30,000 feet 8.90 in HgA (226 torr)
- 50,000 feet 3.44 in HgA (87 torr)
- 70,000 feet 1.31 in HgA (33 torr)
- 100,000 feet 0.315 in HgA (8 torr)*
- per EIA-364-20:Altitude vs. Pressure, Temperature and Density see datasheet
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Vacuum Impregnation
Vacuum Impregnation- Vacuum Impregnation is an advanced modern porosity sealing technique by using vacuum to insure a liquid or compound is impregnated into a matrix or part. The process effectively tests and seals leaks in castings. Vacuum impregnation is also used for mounting and impregnation of porous specimens to stabilize and facilitate examination and preservation. The electrical and electronic component industry uses vacuum impregnation to effectively insulate components such as transformer wire.
https://techreports.larc.nasa.gov/ltrs/PDF/2001/mtg/NASA-2001-33sampe-bwg2.pdf
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Vacuum Encapsulation
Vacuum Encapsulation – Also known as vacuum potting create void-free encapsulation of components thus protecting them form external environmental conditions. The process of encasing/protecting an electronic assembly within a container, typically using a thermosetting material which provides resistance to shock and vibration, or exclusion of moisture and corrosive agents. The main difference between potting and encapsulating is that with the latter, the container is removed from the article. Many types of electrical and electronic devices, from medical implants to automotive engine modules, are insulated and protected from the environment by being encapsulated or embedded within polymeric resins.
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Vacuum Distillation
Vacuum Distillation is a method of distillation whereby the pressure above the solution to be distilled is reduced to less than one Atmosphere causing evaporation of the most volatile liquid(s) (those with the lowest boiling point. Vacuum distillation is used with or without heating the solution; some distillation processes use both vacuum and thermal action.
Vacuum distillation works on the principle that boiling occurs when the vapor pressure of a liquid exceeds the ambient pressure (atmospheric pressure above it or pressure in the distillation apparatus.) In standard thermal distillation, the vapor pressure is increased. In vacuum distillation, the ambient pressure is decreased.
The process is used when liquids to be distilled have high boiling points or chemically change at temperatures near their atmospheric boiling points. Temperature sensitive materials such as complex caratenoids (Beta Carotene) also require vacuum distillation to remove solvents from the mixture while at the same time not damaging the product.
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Vacuum Casting
Vacuum casting is a means of casting small metal parts or jewelry that have fine detail or for casting various plastic materials. This copying technique is typically used for the production of small series of functional plastic prototypes. A porous or vented mold is used and is placed on a table or container where vacuum is applied. The liquid to be cast will be driven into the mold by atmospheric pressure, while the vacuum will also remove trapped air that would otherwise impede the free flow of the liquid casting material. Vacuum casting is applied as an alternative to centrifugal casting of metals which is used in similar situations.
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Vacuum Fumigation
Vacuum Fumigation – Used to eliminate insects, rodents, funguses and molds from various materials such as food, books, art work, etc. Objects are placed into a vacuum chamber. Then, toxic gazes are injected inside the chamber to eliminate any king of life at the surface as well as inside the objects. That gas is then drawn up and neutralized. After that, the objects are ventilated in order to remove any residual gas particles. This chamber should also be equipped with fans or recirculating systems, to ensure even distribution of the fumigant.
The vacuum denies the insect oxygen and facilitates rapid penetration of the commodity by the fumigant. As a result, a vacuum fumigation treatment time may be reduced by as much as 75% as compared to fumigations at atmospheric pressure. Vacuum fumigation is used largely in plant quarantine work and for fumigating materials that are difficult to penetrate at atmospheric pressure. It is also used in some food manufacturing industries for the fumigation of packaged cereals and prepared foods. The procedure cannot be used with tender plants or produce, such as fresh fruits and vegetables, that are unable to withstand reduced pressures. Advantages of vacuum fumigation include not only reduced exposure period and increased penetration by the fumigant, but also many of the previously mentioned advantages associated with the use of a fumigation chamber.
Methods
The two main methods of vacuum fumigation are sustained-vacuum and restored-pressure. The method used is determined by the commodity. The sustained-vacuum method is used for seeds, grains, tobacco, and dry plant products, whereas commodities that cannot withstand prolonged exposure to reduced pressures are treated using the restored-pressure method.
With the sustained-vacuum method, the pressure in the loaded chamber is reduced and the fumigant introduced. The reduced pressure is maintained until the fumigation period ends, at which time atmospheric pressure is restored by allowing air to enter the chamber. The fumigant-air mixture is pumped out, and the cycle of air introduction and evacuation repeated (a process known as “air-washing”) until it is safe to open the chamber door.
The actual pressure used, the length of the fumigation period, and the fumigant dose can be adjusted to fit specific needs. For example, some commodities can withstand lower pressures than others.
The restored-pressure method differs from the sustained-vacuum method in that the reduced pressure is not maintained throughout the fumigation period. Instead, the inside of the chamber is returned to or near atmospheric pressure in one of the following ways:
- Gradual restoration of atmospheric pressure. The required dosage of fumigant is discharged and air is then slowly introduced until a pressure just below atmospheric is reached after 2 hours in a 3-hour exposure period.
- Delayed restoration of atmospheric pressure. Following discharge of the fumigant, the vacuum is sustained for about 45 minutes before air is introduced rapidly into the chamber.
- Immediate restoration of atmospheric pressure. After the fumigant is discharged, atmospheric pressure is rapidly restored in the system by opening one or more valves leading into the chamber. This “released-” or “dissipated-vacuum” method has been used extensively for the fumigation of baled cotton
- Simultaneous introduction of air and fumigant. In this technique, special metering equipment is provided whereby the fumigant is introduced simultaneously with air so that a constant proportion of fumigant to air is maintained until the entire dosage has been introduced.
Once a restored-pressure fumigation is ended, the chamber is aerated by air-washing as described under the sustained-vacuum method.
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Vacuum Storage
Vacuum Storage – Vacuum Desiccator storage provides a contamination- and corrosion-free space for cooling, drying and storage of moisture sensitive material. One potential end-application is for saving and protecting documents. This can be accomplished easily by using special bags and pulling a vacuum, keeping the documents tight, secure and protecting them from hazards such as: Moisture, Insects, Mildew, Water sprinkler discharge. Hazards can destroy stored files without any protection unexpectedly. By putting them in a bag and vacuuming them not only will it protect them but it reduces the cubic volume by up to 25%. Using this process gives you double benefits, protection from environmental hazards and saves expensive storage space.
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Vacuum Volume Reduction
Vacuum Volume Reduction – Shipping and storage costs for goods can be improved by using a vacuum chamber to reduce the volume of certain products. Some sample applications: Fiberglass filter batts, Textile parts, and Bedding products, Paper documents. The process involves placing the product in a bag and then vacuuming the bag to the desired compression level. Digital vacuum controls allow precise vacuum levels so product wrinkling and rebound can be controlled.
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Vacuum Sealing and Gas Flushing
Vacuum Sealing and Gas Flushing – Vacuum Sealing and Packaging, often used in the food and electronics industries. Vacuum packing increases shelf life of perishables, retains aroma, and retards bacterial growth. Many industrial parts and goods require oxidation protection. Traditional forms utilize grease coating and absorbents. Atmosphere or Vacuum packaging offers a low cost alternative. Some potential applications include: Precious Metals, Automotive Parts, Industrial Chemicals, and Electronic components. These products are placed within a bag in its final shipping container and then a vacuum is drawn on the product to remove the oxygen. Depending upon the nature of the product, various gases such as Nitrogen or Carbon Dioxide (CO2) may be gas flushed into the container. Nitrogen as an inert gas is ideal for prolonging the life of food items and is not detrimental to the flavor of any food. CO2 can lower the pH or inhibit the growth of bacteria.
Vacuum Sealing
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Vacuum Metal Joining
Vacuum Metal Joining – Vacuum Brazing (brazing in vacuum atmosphere) is commonly used for certain materials (like aluminum) that readily form oxide layers in air or partial pressure. Titanium based, active metal brazing (ABA) is performed in vacuum and is well suited for bonding metal and non-metal materials without the added time and expense of metalizing or thin-film sputtering. Vacuum brazing is also commonly used for Stainless Steel-type alloys which are ideally suited for bonding Stainless Steel for Medical, Semiconductor equipment and industrial vacuum applications.
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Vacuum Metallizing
Vacuum Metallizing- Vacuum metallizing is the process of evaporating metals (most commonly aluminum) in a vacuum chamber, which then bond to the desired parts to achieve a thin uniform layer. This layer of metal (depending on the pre- and post treatment processes) can be used for:
- EMI/RFI/ESD shielding: Electromagnetic, Radio frequency, and Electrostatic Discharge shielding. For use in electronic, medical, military, aerospace etc. applications
- Reflective Finishes: A lustrous shine used for flash, automotive, emergency, and many other types of lighting.
- Decorative Chrome Coatings: A chrome like coating used to enhance the appearance for a large variety of applications. Including colors, gold, and mattes.
- Custom Chrome Plastic: Custom chrome-like coatings for anything plastic.See ABBESS chambers cube, systems,
Leak Testing
Leak Testing – Helium leak detection, vacuum decay chambers, visible liquid leak detection, visible underwater vacuum leak detection. Leak testing applications include, but are not limited to the following:
- Rigid Packaging
- Flexible Packaging
- Packages with threaded or lug-style closures
- Packages with mechanical dispensing systems
- Filtration membranes/Reverse Osmosis devices
Altitude vs. Pressure, Temperature and Density see datasheet
See ABBESS chambers Acrylic, round, cube, systems, cart mounted
Product Integrity
Product integrity – Covers an unlimied array of potential applications including:
- Flexible material seams
- Effects of altitude on packaging
- Gaskets
- Bond Strength
- Corrosion
- Contamination
Hermeticity
Definition: Hermetic – Completely sealed, especially against the escape or entry of air.
Hermeticity has been defined in various ways; for example, as “the state or condition of being airtight,”2 or, alternatively, as “sealed so that the object is gastight.” However, all materials leak, or more accurately, all materials are permeable to some gas to some degree. Welds and joints between materials may have preexisting cracks or pores that provide a leakage path. The total “leak” is thus a combination of both the bulk permeation through the material and any open leak paths that lead directly from the internal to the external environment. Therefore, the process of ensuring hermeticity can be described as the selection of materials and manufacturing techniques that yield an enclosure that has sufficient material thickness to impede the diffusion of gas into the internal package cavity and that can be sealed without pinholes, cracks, or other discontinuities that provide a direct leak path.
Measuring
Hermeticity is commonly measured by dye-penetrant, bubble-emission, pressure-decay, microbial-ingress, radioactive, and mass spectrometer systems. All of these techniques are commercially available and can be used to detect leaks. Some–like the bubble and dye methods–can pinpoint the exact location of a leak. Others only detect the summation of all the leaks present and are used in go/no-go inspections.
Regardless of the measurement system, the basic approach is the same. A pressure difference is developed between the internal volume of the package and the external environment. This pressure gradient causes gas or liquid to diffuse or leak through the bulk material or seal area. The material “leaking” through to the external environment is then sensed. In the case of radioactive, microbial, and mass spectrometer methods, the test can be both qualitative (what is leaking) and quantitative (how much is leaked). For the purpose of this article, all leak rates refer to helium rates measured at 1 atm pressure differential and 20 °C and are defined as helium atoms per cubic centimeter per second (for example, 10-5 He/cm3/sec (STP)).
More thorough discussions of leak-rate measurement are provided in a number of sources and will not be covered here. However, a few key points should be highlighted. The permeation of materials through the barrier is a function of the concentration of the diffusing material, its affinity for the matrix (chemical adsorption), and the physical size of the molecules. The major point is that just because a joint leaks helium at a rapid rate, the same joint may not leak water vapor because of pore size or chemical binding of the moisture in the base material. This is also true for direct leak paths, for which the path may be so tortuous and small in diameter that the leaking molecule may not physically fit. In another case, the pressure drop across the leak path may be so minimal that the leak becomes diffusion limited, with the added effects of absorption of the material to the walls of the leak channel. In these cases, the package may actually be “hermetic” according to the needs of the client, even though a leakage path exists.
Leak Site Identification
Helium spray sniff testing is a technique that can be utilized to isolate hermetic leaks on open cavity packages as well as packages subjected. Typically, a helium spray creates a small envelope of helium in the proximity of a leak site region would be measured and recorded.
Fluorescent Dye Impregnation
Fluorescent dye impregnation is utilized to identify leak site regions and characterize the physical attributes of the ingress pathways to improve package sealing processes. This technique also eliminates the problem of misinterpretation when cross-sectioning fragile materials.
Fine Leak
Devices are typically preconditioned in a helium pressurized chamber and, after the required conditions are met, the helium leak rate is measured and recorded, applying pass/fail criteria. Devices sealed with helium need not be pressurized if requested.
Expanded Fine Leak for Other Gases and Compounds
Specialized leak testing is available for determining leak rates for gases other than helium. Leak rates of various gases (i.e. Argon, CO2, Acetic Acid, Ethylene Glycol, etc.) may be measured at low leak rates utilizing a specialized mass spectrometer tuned for the particular substance of interest. Applicable standards are normally available in a wide range of leak rates.
Gross Leak
A device with a gross leak could theoretically pass the fine leak test. Therefore, this test is typically performed after fine leak. Depending on the requirement of the specification being followed, gross leak may be performed by two different methods.
1. The device is submerged in an indicator fluid tank at a specified high temperature of 125 ° C, and observed for evidence of bubble stream emanating from a gross leak site. A lower temperature may be used depending on device material constraints.
2. The test may require preconditioning in a pressurized chamber filled with an inert detector fluid that characteristically has a low boiling point. After preconditioning, the devices are submerged in an inert indicator fluid with a higher boiling point. In theory, any detector fluid located within the internal cavity of the package would boil when exposed to the high temperature of the indicator fluid, thus creating a bubble stream from the gross leak site.
Porosity
Definition: Porosity – The ratio of the volume of all the pores in a material to the volume of the whole.
There are several ways to estimate the porosity of a given material or mixture of materials, which is called your material matrix.
- The Volume/Density method is fast and surprisingly accurate (normally within 2% of the actual porosity). To do this method you pour your material into a beaker, cylinder or some other container of a known volume. Weigh your container so you know its empty weight, then pour your material into the container. Tap the side of the container until it has finished settling and measure the volume in the container. Then weigh your container full of this material, so you can subtract the weight of the container to know just the weight of just your material. So now you have both the volume and the weight of the material. The weight of your material divided by the density of your material gives you the volume that your material takes up, minus the pore volume. (The assumed density of most rocks, sand, glass, etc. is assumed to be 2.65g/cc. If you have a different material, you may look up its density) So, the pore volume is simply equal to the total volume minus the mateial volume, or more directly (pore volume) = (total volume) – (material volume).
- Water Saturation Method is slightly harder to do, but it more accurate and more direct. Again, take a known volume of your material and also a known volume of water. (Make sure the beaker or container is large enough to hold your material as well.) Slowly dump your material into the water and let it saturate as you pour it in. Then seal the beaker (with a piece of parafilm tape or if you don’t have parafilm tape a plastic bag tied around the beaker will do.) and let it sit for a few hours to insure the material is fully saturated. Then remove the unsaturated water from the top of the beaker and measure its volume. The total volume of the water originally in the beaker minus the amount of water not saturated is the volume of the pore space, or again more directly (pore volume) = (total volume of water) – (unsaturated water).
- Water Evaporation Method is the hardest to do, but is also the most accurate. Take a fully saturated, known volume of your material with no excess water on top. Weigh your container with the material and water and then place your container into a heater and/or vacuum chamber to dry it out. Once dry, weigh your sample. Since the density of water is 1 g/cc, the difference of the weights of the saturated versus the dried sample is equal to the volume of the water removed from the sample (assuming you are measuring in grams), which is exactly the pore volume. So once again, (pore volume in cubic centemeters) = (weight of saturated sample in grams) – (weight of dried sample in grams).
Permeability
Definition: Permeability – The rate of flow of a liquid or gas through a porous material.- Liquid permeability
- Gas permeability
- Difusion permeability
- Water vapor permeability
- Liquid permeability
Absorprtion
Definition: Absorprtion – absorption of particles of gas or liquid into liquid or solid materials.
Saturation
Definition: Saturation – saturation is the point at which a solution of a substance can dissolve no more of that substance.
Adsorption
Definition: Adsorption – adsorption of particles of gas or liquid on to solid materials.
Getter
Definition: Getter – A material added in small amounts during a chemical or metallurgical process to absorb impurities
Specific Gravity
Definition: Specific Gravity – the density of a substance relative to the density of water
– Vacuum sealing method
Vapor Pressure
Definition: Vapor Pressure – The pressure exerted by a vapor in equilibrium with its solid or liquid phase.
Density
Definition: Density – The mass per unit volume of a substance under specified conditions of pressure and temperature.
There are several ways to measure the density of gas. One way is to take a certain amount of gas and weigh it. (Yes, you really can weigh a gas. One way to do this is by filling a container with the gas and weighing it, then using a vacuum pump to empty the container out completely and weighing it again.) If you know how much the gas weighs and how much space it takes up, you can figure out the density. (Density = mass / volume)
Deposition
Definition: Deposition – A coating or crust left on a surface.
Instrument Calibration
For example:
- Helium Leak detectors
- Thermocouples
Volatility
- Total Mass Loss
- Collected Volatile Condensable Materials
- Total Mass Flux
Emissions
For example:
- Acoustic
- Gaseous
- Electromagnetic EM
Laser windows for vacuum
Abbess uses semiconductor Grade quartz for its vacuum windows,
GE124 or NSG-N and are polished to a commercial grade finish 80/50 scratch dig. Flatness and parallelism is +/-.005To check the mechanical, thermal, optical, IR Transmission and other properties please goto www.gequartz.com