Waterproofing is the process of making an object or structure waterproof or water-resistant so that it remains unaffected by water or resisting the ingress of water under specified conditions. Such items may be used in underwater to specified depths. Water resistant and waterproof refer to penetration of water in its liquid state and under pressure, whereas damp proof refers to resistance to humidity or dampness. Permeation of water vapor through a material or structure is reported as a moisture vapor transmission rate; the hulls of boats and ships were once waterproofed by applying pitch. Modern items may be waterproofed by applying water-repellent coatings or by sealing seams with gaskets or o-rings. Waterproofing is used in reference to building structures, canvas, electronic devices and paper packaging. In construction, a building or structure is waterproofed with the use of membranes and coatings to protect contents, structural integrity; the waterproofing of the building envelope in construction specifications is listed under 07 - Thermal and Moisture Protection within MasterFormat 2004, by the Construction Specifications Institute, includes roofing and waterproofing materials.
In building construction, waterproofing is a fundamental aspect of creating a building envelope, a controlled environment. The roof covering materials, siding and all of the various penetrations through these surfaces must be water-resistant and sometimes waterproof. Roofing materials are designed to be water-resistant and shed water from a sloping roof, but in some conditions, such as ice damming and on flat roofs, the roofing must be waterproof. Many types of waterproof membrane systems are available, including felt paper or tar paper with asphalt or tar to make a built-up roof, other bituminous waterproofing, ethylene propylene diene monomer EPDM rubber, polyvinyl chloride, liquid roofing, more. Walls are not subjected to standing water, the water-resistant membranes used as housewraps are designed to be porous enough to let moisture escape. Walls have vapor barriers or air barriers. Damp proofing is another aspect of waterproofing. Masonry walls are built with a damp-proof course to prevent rising damp, the concrete in foundations needs to be damp-proofed or waterproofed with a liquid coating, basement waterproofing membrane, or an additive to the concrete.
Within the waterproofing industry, below-ground waterproofing is divided into two areas: Tanking: This is waterproofing used where the below-ground structure will be sitting in the water table continuously or periodically. This causes hydrostatic pressure on both the membrane and structure, requires full encapsulation of the basement structure in a tanking membrane, under slab and walls. Damp proofing: This is waterproofing used where the water table is lower than the structure and there is good free-draining fill; the membrane deals with shedding of water and the ingress of water vapor only, with no hydrostatic pressure. This incorporates a damp proof membrane to the walls with a polythene DPM under slab. With higher grade DPM, some protection from short-term Hydrostatic pressure can be gained by transitioning the higher quality wall DPM to the slab polythene under footing, rather than at the footing face. In buildings using earth sheltering, a potential problem is too much humidity, so waterproofing is critical.
Water seepage can lead to mold growth, causing significant air quality issues. Properly waterproofing foundation walls is required to prevent seepage. Another specialized area of waterproofing is roof top balconies. Waterproofing systems have become quite sophisticated and are a specialized area. Failed waterproof decks, polymer or tile, are one of the leading causes of water damage to building structures, of personal injury when they fail. Where major problems occur in the construction industry is when improper products are used for the wrong application. While the term waterproof is used for many products, each of them has a specific area of application, when manufacturer specifications and installation procedures are not followed, the consequences can be severe. Another factor, is the impact of contraction on waterproofing systems for decks. Decks move with changes in temperatures, putting stress on the waterproofing systems. One of the leading causes of waterproof deck system failures is the movement of underlying substrates that cause too much stress on the membranes resulting in a failure of the system.
While beyond the scope of this reference document, waterproofing of decks and balconies is a complex of many complimentary elements. These include the waterproofing membrane used, adequate slope-drainage, proper flashing details, proper construction materials; the penetrations through a building envelope must be built in a way such that water does not enter the building, such as using flashing and special fittings for pipes, wires, etc. Some caulkings are durable. Many types of geomembranes are available to control water, gases, or pollution. From the late 1990s to the 2010s, the construction industry has had technological advances in waterproofing materials, including integral waterproofing systems and more advanced membrane materials. Integral systems such as hycrete work within the matrix of a concrete structure, giving the concrete itself a waterproof quality. There are two main types of integral waterproofing systems: the hydrophilic
The lotus effect refers to self-cleaning properties that are a result of ultrahydrophobicity as exhibited by the leaves of Nelumbo or "lotus flower". Dirt particles are picked up by water droplets due to the micro- and nanoscopic architecture on the surface, which minimizes the droplet's adhesion to that surface. Ultrahydrophobicity and self-cleaning properties are found in other plants, such as Tropaeolum, Alchemilla, on the wings of certain insects; the phenomenon of ultrahydrophobicity was first studied by Dettre and Johnson in 1964 using rough hydrophobic surfaces. Their work developed a theoretical model based on experiments with glass beads coated with paraffin or PTFE telomer; the self-cleaning property of ultrahydrophobic micro-nanostructured surfaces was studied by Wilhelm Barthlott and Ehler in 1977, who described such self-cleaning and ultrahydrophobic properties for the first time as the "lotus effect". Other biotechnical applications have emerged since the 1990s; the high surface tension of water causes droplets to assume a nearly spherical shape, since a sphere has minimal surface area, this shape therefore demands least solid-liquid surface energy.
On contact with a surface, adhesion forces result in wetting of the surface. Either complete or incomplete wetting may occur depending on the structure of the surface and the fluid tension of the droplet; the cause of self-cleaning properties is the hydrophobic water-repellent double structure of the surface. This enables the contact area and the adhesion force between surface and droplet to be reduced resulting in a self-cleaning process; this hierarchical double structure is formed out of a characteristic epidermis and the covering waxes. The epidermis of the lotus plant possesses papillae with 10 µm to 20 µm in height and 10 µm to 15 µm in width on which the so-called epicuticular waxes are imposed; these superimposed waxes form the second layer of the double structure. This system regenerates; this bio-chemical property is responsible for the functioning of the water repellency of the surface. The hydrophobicity of a surface can be measured by its contact angle; the higher the contact angle the higher the hydrophobicity of a surface.
Surfaces with a contact angle < 90° are referred to as hydrophilic and those with an angle >90° as hydrophobic. Some plants show contact angles up to 160° and are called ultrahydrophobic, meaning that only 2–3% of the surface of a droplet is in contact. Plants with a double structured surface like the lotus can reach a contact angle of 170°, whereby the droplet's contact area is only 0.6%. All this leads to a self-cleaning effect. Dirt particles with an reduced contact area are picked up by water droplets and are thus cleaned off the surface. If a water droplet rolls across such a contaminated surface the adhesion between the dirt particle, irrespective of its chemistry, the droplet is higher than between the particle and the surface; as this self-cleaning effect is based on the high surface tension of water it does not work with organic solvents. Therefore, the hydrophobicity of a surface is no protection against graffiti; this effect is of a great importance for plants as a protection against pathogens like fungi or algae growth, for animals like butterflies and other insects not able to cleanse all their body parts.
Another positive effect of self-cleaning is the prevention of contamination of the area of a plant surface exposed to light resulting in reduced photosynthesis. When it was discovered that the self-cleaning qualities of ultrahydrophobic surfaces come from physical-chemical properties at the microscopic to nanoscopic scale rather than from the specific chemical properties of the leaf surface, the discovery opened up the possibility of using this effect in manmade surfaces, by mimicking nature in a general way rather than a specific one; some nanotechnologists have developed treatments, paints, roof tiles and other surfaces that can stay dry and clean themselves by replicating in a technical manner the self-cleaning properties of plants, such as the lotus plant. This can be achieved using special fluorochemical or silicone treatments on structured surfaces or with compositions containing micro-scale particulates. In addition to chemical surface treatments, which can be removed over time, metals have been sculpted with femtosecond pulse lasers to produce the lotus effect.
The materials are uniformly black at any angle, which combined with the self-cleaning properties might produce low maintenance solar thermal energy collectors, while the high durability of the metals could be used for self-cleaning latrines to reduce disease transmission. Further applications have been marketed, such as self-cleaning glasses installed in the sensors of traffic control units on German autobahns developed by a cooperation partner; the Swiss companies HeiQ and Schoeller Textil have developed stain-resistant textiles under the brand names "HeiQ Eco Dry" and "nanosphere" respectively. In October 2005, tests of the Hohenstein Research Institute showed that clothes treated with NanoSphere technology allowed tomato sauce and red wine to be washed away after a few washes. Another possible application is thus with self-cleaning awnings and sails, which otherwise become dirty and difficult to clean. Superhydrophobic coatings applied to microwave antennas can reduce rain fade and the buildup of ice and snow.
"Easy to clean" products in ads are mistaken in the name of the self
In chemistry, hydrophobicity is the physical property of a molecule, repelled from a mass of water. In contrast, hydrophiles are attracted to water. Hydrophobic molecules tend to be nonpolar and, prefer other neutral molecules and nonpolar solvents; because water molecules are polar, hydrophobes do not dissolve well among them. Hydrophobic molecules in water cluster together, forming micelles. Water on hydrophobic surfaces will exhibit a high contact angle. Examples of hydrophobic molecules include the alkanes, oils and greasy substances in general. Hydrophobic materials are used for oil removal from water, the management of oil spills, chemical separation processes to remove non-polar substances from polar compounds. Hydrophobic is used interchangeably with lipophilic, "fat-loving". However, the two terms are not synonymous. While hydrophobic substances are lipophilic, there are exceptions, such as the silicones and fluorocarbons; the term hydrophobe comes from the Ancient Greek ὑδρόφοβος, "having a horror of water", constructed from ὕδωρ, "water", φόβος, "fear".
The hydrophobic interaction is an entropic effect originating from the disruption of the dynamic hydrogen bonds between molecules of liquid water by the nonpolar solute forming a clathrate-like structure around the non-polar molecules. This structure formed is more ordered than free water molecules due to the water molecules arranging themselves to interact as much as possible with themselves, thus results in a higher entropic state which causes non-polar molecules to clump together to reduce the surface area exposed to water and decrease the entropy of the system. Thus, the 2 immiscible phases will change so that their corresponding interfacial area will be minimal; this effect can be visualized in the phenomenon called phase separation. Superhydrophobic surfaces, such as the leaves of the lotus plant, are those that are difficult to wet; the contact angles of a water droplet exceeds 150°. This is referred to as the lotus effect, is a physical property related to interfacial tension, rather than a chemical property.
In 1805, Thomas Young defined the contact angle θ by analyzing the forces acting on a fluid droplet resting on a solid surface surrounded by a gas. Γ SG = γ SL + γ LG cos θ where γ SG = Interfacial tension between the solid and gas γ SL = Interfacial tension between the solid and liquid γ LG = Interfacial tension between the liquid and gasθ can be measured using a contact angle goniometer. Wenzel determined that when the liquid is in intimate contact with a microstructured surface, θ will change to θW* cos θ W ∗ = r cos θ where r is the ratio of the actual area to the projected area. Wenzel's equation shows that microstructuring a surface amplifies the natural tendency of the surface. A hydrophobic surface becomes more hydrophobic when microstructured – its new contact angle becomes greater than the original. However, a hydrophilic surface becomes more hydrophilic when microstructured – its new contact angle becomes less than the original. Cassie and Baxter found that if the liquid is suspended on the tops of microstructures, θ will change to θCB*: cos θ CB ∗ = φ − 1 where φ is the area fraction of the solid that touches the liquid.
Liquid in the Cassie–Baxter state is more mobile than in the Wenzel state. We can predict whether the Wenzel or Cassie–Baxter state should exist by calculating the new contact angle with both equations. By a minimization of free energy argument, the relation that predicted the smaller new contact angle is the state most to exist. Stated in mathematical terms, for the Cassie–Baxter state to exist, the following inequality must be true. Cos θ > φ − 1 r − φ A recent alternative criterion for the Cassie–Baxter state asserts that the Cassie–Baxter state exists when the following 2 criteria are met:1) Contact line forces overcome body forces of unsupported droplet weight and 2) The microstructures are tall enough to prevent the liquid that bridges microstructures from touching the base of the microstructures. A new criterion for the switch between Wenzel and Cassie-Baxter states has been developed based on surface roughness and surface energy; the criterion focuses on the air-trapping capability under liquid droplets on rough surfaces, which could tell whether Wenzel's model or Cassie-Baxter's model should be used for certain combination of surface roughness and energy.
Contact angle is a measure of static hydrophobicity, contact angle hysteresis and slide angle are dynamic measures. Contact angle hysteresis is a phenomenon that characterizes surface h
Ultrahydrophobic surfaces are hydrophobic, i.e. difficult to wet. The contact angles of a water droplet on an ultrahydrophobic material exceed 150°; this is referred to as the lotus effect, after the superhydrophobic leaves of the lotus plant. A droplet striking these kinds of surfaces can rebound like an elastic ball, or pancake. In 1805, Thomas Young defined the contact angle θ by analysing the forces acting on a fluid droplet resting on a solid surface surrounded by a gas. Γ S G = γ S L + γ L G cos θ where γ S G = Interfacial tension between the solid and gas γ S L = Interfacial tension between the solid and liquid γ L G = Interfacial tension between the liquid and gasθ can be measured using a contact angle goniometer. Wenzel determined that when the liquid is in intimate contact with a microstructured surface, θ will change to θ W ∗ cos θ W ∗ = r cos θ where r is the ratio of the actual area to the projected area. Wenzel's equation shows that microstructuring a surface amplifies the natural tendency of the surface.
A hydrophobic surface becomes more hydrophobic when microstructured – its new contact angle becomes greater than the original. However, a hydrophilic surface becomes more hydrophilic when microstructured – its new contact angle becomes less than the original. Cassie and Baxter found that if the liquid is suspended on the tops of microstructures, θ will change to θ C B ∗ cos θ C B ∗ = φ – 1where φ is the area fraction of the solid that touches the liquid. Liquid in the Cassie-Baxter state is more mobile than in the Wenzel state, it can be predicted whether the Wenzel or Cassie-Baxter state should exist by calculating the new contact angle with both equations. By a minimization of free energy argument, the relation that predicted the smaller new contact angle is the state most to exist. Stated mathematically, for the Cassie-Baxter state to exist, the following inequality must be true. Cos θ < /A recent alternative criteria for the Cassie-Baxter state asserts that the Cassie-Baxter state exists when the following 2 criteria are met: 1) Contact line forces overcome body forces of unsupported droplet weight and 2) The microstructures are tall enough to prevent the liquid that bridges microstructures from touching the base of the microstructures.
Contact angle is a measure of static hydrophobicity, contact angle hysteresis and slide angle are dynamic measures. Contact angle hysteresis is a phenomenon; when a pipette injects a liquid onto a solid, the liquid will form some contact angle. As the pipette injects more liquid, the droplet will increase in volume, the contact angle will increase, but its three phase boundary will remain stationary until it advances outward; the contact angle the droplet had before advancing outward is termed the advancing contact angle. The receding contact angle is now measured by pumping the liquid back out of the droplet; the droplet will decrease in volume, the contact angle will decrease, but its three phase boundary will remain stationary until it recedes inward. The contact angle the droplet had before receding inward is termed the receding contact angle; the difference between advancing and receding contact angles is termed contact angle hysteresis and can be used to characterize surface heterogeneity and mobility.
Surfaces that are not homogeneous will have domains. The slide angle is another dynamic measure of hydrophobicity and is measured by depositing a droplet on a surface and tilting the surface until the droplet begins to slide. Liquids in the Cassie-Baxter state exhibit lower slide angles and contact angle hysteresis than those in the Wenzel state. A simple model can be used to predict the effectiveness of a manmade micro- or nano-fabricated surface for its conditional state, contact angle and contact angle hysteresis; the main factor of this model is the contact line density, Λ, the total perimeter of asperities over a given unit area. The critical contact line density Λc is a function of body and surface forces, as well as the projected area of the droplet. Λ C = − ρ g V 1 / 3 ( ( 3 + ( 1
Electrical resistivity and conductivity
Electrical resistivity and its converse, electrical conductivity, is a fundamental property of a material that quantifies how it resists or conducts the flow of electric current. A low resistivity indicates a material that allows the flow of electric current. Resistivity is represented by the Greek letter ρ; the SI unit of electrical resistivity is the ohm-metre. For example, if a 1 m × 1 m × 1 m solid cube of material has sheet contacts on two opposite faces, the resistance between these contacts is 1 Ω the resistivity of the material is 1 Ω⋅m. Electrical conductivity or specific conductance is the reciprocal of electrical resistivity, it represents a material's ability to conduct electric current. It is signified by the Greek letter σ, but κ and γ are sometimes used; the SI unit of electrical conductivity is siemens per metre. In an ideal case, cross-section and physical composition of the examined material are uniform across the sample, the electric field and current density are both parallel and constant everywhere.
Many resistors and conductors do in fact have a uniform cross section with a uniform flow of electric current, are made of a single material, so that this is a good model. When this is the case, the electrical resistivity ρ can be calculated by: ρ = R A ℓ, where R is the electrical resistance of a uniform specimen of the material ℓ is the length of the specimen A is the cross-sectional area of the specimenBoth resistance and resistivity describe how difficult it is to make electrical current flow through a material, but unlike resistance, resistivity is an intrinsic property; this means that all pure copper wires, irrespective of their shape and size, have the same resistivity, but a long, thin copper wire has a much larger resistance than a thick, short copper wire. Every material has its own characteristic resistivity. For example, rubber has a far larger resistivity than copper. In a hydraulic analogy, passing current through a high-resistivity material is like pushing water through a pipe full of sand—while passing current through a low-resistivity material is like pushing water through an empty pipe.
If the pipes are the same size and shape, the pipe full of sand has higher resistance to flow. Resistance, however, is not determined by the presence or absence of sand, it depends on the length and width of the pipe: short or wide pipes have lower resistance than narrow or long pipes. The above equation can be transposed to get Pouillet's law: R = ρ ℓ A; the resistance of a given material is proportional to the length, but inversely proportional to the cross-sectional area. Thus resistivity can be expressed using the SI unit "ohm metre" (i.e ohms divided by metres and multiplied by square metres }. For example, if A = 1 m2 ℓ = 1 m the resistance of this element in ohms is numerically equal to the resistivity of the material it is made of in Ω⋅m. Conductivity, σ, is the inverse of resistivity: σ = 1 ρ. Conductivity has SI units of "siemens per metre". For less ideal cases, such as more complicated geometry, or when the current and electric field vary in different parts of the material, it is necessary to use a more general expression in which the resistivity at a particular point is defined as the ratio of the electric field to the density of the current it creates at that point: ρ = E J, where ρ is the resistivity of the conductor material, E is the magnitude of the electric field, J is the magnitude of the current density,in which E and J are inside the conductor.
Conductivity is the inverse of resistivity. Here, it is given by: σ = 1 ρ = J E. For example, rubber is a material with large ρ and small σ—because a large electric field in rubber makes no current flow through it. On the other hand, copper is a material with small ρ and large σ—because a small electric field pulls a lot of current through it; as shown below, this expression simplifies to a single number when the electric field and current density are constant in the material. When the resistivity of a material has a directional component, the most general definition of resistivity must be used, it starts from the tensor-vector form of Ohm's law which relates the electric field inside a material to the electric current flow. This equation is general, meaning it is valid in all cases, including those mentioned above. However, this definition is the most complicated, so it is only directly used in anisotropic cases, where the more simple definitions cannot be applied. If the material is not anisotropic
The IP Code, International Protection Marking, IEC standard 60529, sometimes interpreted as Ingress Protection Marking and rates the degree of protection provided against intrusion, accidental contact, water by mechanical casings and electrical enclosures. It is published by the International Electrotechnical Commission; the equivalent European standard is EN 60529. The standard aims to provide users more detailed information than vague marketing terms such as waterproof. For example, a cellular phone rated at IP68 is "dust resistant" and can be "immersed in 1.5 meters of freshwater for up to 30 minutes". An electrical socket rated IP22 is protected against insertion of fingers and will not be damaged or become unsafe during a specified test in which it is exposed to vertically or nearly vertically dripping water. IP22 or IP2X are typical minimum requirements for the design of electrical accessories for indoor use; the digits indicate conformity. The digit 0 is used; the digit is replaced with the letter X when insufficient data has been gathered to assign a protection level.
There are no hyphens in a genuine IP code. IPX-8 is thus an invalid IP code; this page contains a combination of IEC 60529 and other standards, such as ISO 20653. The original documents are available for purchase, have important and specific requirements that cannot be reprinted due to copyright restrictions; this includes drawings specifying the required test equipment, such as the shape of water nozzles used for water jet testing. Additional standards are referenced that may contain important information. One must refer to the latest revision of the required standard when conducting tests for agency certification; this table shows what each part of the IP code represents. The first digit indicates the level of protection that the enclosure provides against access to hazardous parts and the ingress of solid foreign objects; the second digit indicates the level of protection that the enclosure provides against harmful ingress of water. The ratings for water ingress are not cumulative beyond IPX6.
A device, compliant with IPX7, covering immersion in water, need not be compliant with IPX5 or IPX6, covering exposure to water jets. A device which meets both tests is indicated by listing both tests separated by a slash, e.g. IPX5/IPX7. Further letters can be appended to provide additional information related to the protection of the device: The letter K is specified in DIN 40050-9, not in IEC 60529. IP codes with the letter "K" are from ISO 20653:2013 Road Vehicles-Degrees of protection, which states that it is in accordance with IEC 60529 except for the "K" tests, which describe special requirements for road vehicles; the test specifies a spray nozzle, fed with 80 °C water at 8–10 MPa and a flow rate of 14–16 L/min. The nozzle is held 10–15 cm from the tested device at angles of 0°, 30°, 60° and 90° for 30 seconds each; the test device sits on a turntable. The IPx9 specification in IEC 60529 has details for testing larger specimens that will not fit on a turntable test fixture; the IP69K test specification was developed for road vehicles those that need regular intensive cleaning, but it finds use in other areas.
German standard DIN 40050-9 extended the older IEC 60529 rating system with an IP69K rating for high-pressure, high-temperature wash-down applications. DIN 40050-9 has been replaced by ISO 20653:2013 Road Vehicles-Degrees of protection; such enclosures must not only be dust-tight, but it must be able to withstand high-pressure and steam cleaning. By 2013 IEC 60529 added level 9 water ingress testing, with IPx9 being the same spray test as IP69K adding a drawing of a fixture to verify the water pressure. In the USA, the National Electrical Manufacturers Association defines NEMA enclosure types in NEMA standard number 250; the following table outlines. Ratings between the two standards are not directly equivalent: NEMA ratings require additional product features and tests not addressed by IP ratings; the inclusion of an Ingress Protection rating has become common for use in the consumer electronics market with devices such as mobile phones, tablet computers and cameras now being sold as water resistant and dustproof.
Some manufacturers have produced IP rated smartphones, aimed at consumers who are concerned about their handsets getting submerged in liquids or getting covered in dust. With the availability of portable devices, the desire to get outside with active lifestyles, portable speakers have become popular with the rugged consumer market for those who enjoy outdoor recreation, extreme sports as well. EN 62262 – IK code on resistance to mechanical impacts MIL-STD-810 U. S. Military connector specifications for military equivalents Reference Chart - Downloadable PDF reference chart for offline use. Water Resistant mark on wrist watches 2001 edition of the standard
Water Resistant mark
Water Resistant is a common mark stamped on the back of wrist watches to indicate how well a watch is sealed against the ingress of water. It is accompanied by an indication of the static test pressure that a sample of newly manufactured watches were exposed to in a leakage test; the test pressure can be indicated either directly in units of pressure such as bar, atmospheres, or as an equivalent water depth in metres. An indication of the test pressure in terms of water depth does not mean a water-resistant watch was designed for repeated long-term use in such water depths. For example, a watch marked 30 metres water resistant cannot be expected to withstand activity for longer time periods in a swimming pool, let alone continue to function at 30 metres under water; this is because the test is conducted only once using static pressure on a sample of newly manufactured watches. As only a small sample is tested there is likelihood that any individual watch is not water resistant to the certified depth or at all.
The test for qualifying a diving watch for repeated usage in a given depth includes safety margins to take factors into account like aging of the seals, the properties of water and seawater changing water pressure and temperature, as well as dynamic mechanical stresses encountered by a watch. Every diving watch has to be tested for water resistance or water-tightness and resistance at a water overpressure as it is defined; the International Organization for Standardization issued a standard for water-resistant watches which prohibits the term waterproof to be used with watches, which many countries have adopted. This standard was introduced in 1990 as the ISO 2281:1990 and only designed for watches intended for ordinary daily use and are resistant to water during exercises such as swimming for a short period, they may be used under conditions where temperature vary. However, whether they bear an additional indication of overpressure or not, they are not intended for submarine diving; the ISO 2281 standard specifies a detailed testing procedure for each mark that defines not only pressures but test duration, water temperature, other parameters.
Besides this ISO 2859-2 Sampling plans indexed by limiting quality for isolated lot inspection and ISO 2859-3 Sampling procedures for inspection by attributes – Part 3: Skip-lot sampling procedures concerning procedures regarding lot sampling testing come into play, since not every single watch has to be tested for ISO 2281 approval. ISO 2281 water resistance testing of a watch consists of: Resistance when immersed in water at a depth of 10 cm. Immersion of the watch in 10 cm of water for 1 hour. Resistance of operative parts. Immersion of the watch in 10 cm of water with a force of 5 N perpendicular to the crown and pusher buttons for 10 minutes. Condensation test; the watch shall be placed on a heated plate at a temperature between 40 °C and 45 °C until the watch has reached the temperature of the heated plate. A drop of water, at a temperature between 18 °C and 25 °C shall be placed on the glass of the watch. After about 1 minute, the glass shall be wiped with a dry rag. Any watch which has condensation on the interior surface of the glass shall be eliminated.
Resistance to different temperatures. Immersion of the watch in 10 cm of water at the following temperatures for 5 minutes each, 40 °C, 20 °C and 40 °C again, with the transition between temperatures not to exceed 1 minute. No evidence of water intrusion or condensation is allowed. Resistance to water overpressure. Immersion of the watch in a suitable pressure vessel and subjecting it within 1 minute to the rated pressure for 10 minutes, or to 2 bar in case where no additional indication is given; the overpressure is reduced to the ambient pressure within 1 minute. No evidence of water intrusion or condensation is allowed. Resistance to air overpressure. Exposing the watch to an overpressure of 2 bar; the watch shall show no air-flow exceeding 50 μg/min. No magnetic or shock resistance properties are required. No negative pressure test is required. No strap attachment test is required. No corrosion test is required. Except the thermal shock resistance test all further ISO 2281 testing should be conducted at 18 °C to 25 °C temperature.
Regarding pressure ISO 2281 defines: 1 bar = 105 Pa = 105 N/m2. This has since be replaced by the ISO 22810:2010 standard, which covers all activities up to specified depth and clears up ambiguities with the previous standard. In practice, the survivability of the watch will depend not only on the water depth, but on the age of the sealing material, past damage and additional mechanical stresses; the standards and features for diving watches are regulated by the ISO 6425 – Divers' watches international standard. This standard was introduced in 1996. ISO 6425 defines such watches as: A watch designed to withstand diving in water at depths of at least 100 m and possessing a system to control the time. Diving watches are tested in static or still water under 125% of the rated pressure, thus a watch with a 200-metre rating will be water resistant if it is stationary and under 250 metres of static water. ISO 6425 testing of the water resistance or water-tightness and resistance at a water overpressure as it is defined is fundamentally different from non-dive watches, because every single watch has to be tested.
Testing diving watches for ISO 6425 compliance is voluntary and involves costs, so not every manufacturer present their watches for certification according to this standard. ISO 6425 testing of a dive