Watertightness
Under water resistance is understood that quality of materials, components, complex devices or clothing that sufficiently prevents the penetration of water.
It is possible to make something completely waterproof, but mostly uneconomical or has other disadvantages. For example, protective clothing that is comfortable to wear - such as a raincoat or mountain boots - should be impervious to normal rain, but still be breathable . It is also seldom necessary for clothing to strive for complete impermeability to heavy rain .
Standards: International Protection Codes (IP ##) for technical devices. Water column for textiles (millimeters) .
Clocks and technical devices
Clocks and technical devices can be protected against moisture and water to varying degrees by means of an appropriate construction method, although this mainly depends on the planned type of use or location. Naturally, better protection also increases the manufacturing and maintenance costs of a product.
Clocks
General
Waterproof wristwatches are wristwatches whose original case is resistant to water penetration to a specified depth. A wristwatch can be described as “waterproof” if it is resistant to sweat, water droplets and rain and if no water penetrates for 30 minutes when diving to a depth of one meter. Similarly, the "waterproof" ( English water-resistant ) at watchcases understood. Watches with this marking should be resistant to (hand) washing, splashing water, etc. This refers to normal use under conditions where water pressure and temperatures do not vary significantly (see DIN 8310 September 2010, NIHS 92-20 and ISO 2281). A wristwatch called waterproof is never completely airtight, i.e. completely protected against the ingress of water, but the mass flow into the watch is below a specified value of 50 µg / min for defined test conditions (cf. DIN 8310 December 1984). In everyday life, this means that water can penetrate the watch, e.g. B. if it lies in the water for a long time or is exposed to high water pressure . Simple watches are splash-proof , which means that they can survive in a puddle for a few seconds, but not for a long time. In the case of more expensive products, it is therefore indicated for which pressure and how long they are designed. However, it should be noted that movement (e.g. swimming) increases the pressure on the watch. The indication of 3 bar means that the watch can withstand a pressure of 3 bar for a limited time (see DIN 8310 September 2010). Such a classification is also given for diving watches , whereby separate requirements or test conditions apply here (cf. DIN 8306 September 1983 and ISO 6425), whereby one can speak of a "diving watch" if the watch is used at least one hour in 100 Meters of water depth remains waterproof.
| Pressure (water column) | classification | comment |
|---|---|---|
| 3 bar ≈ 3 atm (≈ 20 m) | The clock keeps water splashes out |
The watch can withstand a pressure of 3 bar (corresponds to 30 m water column or approx. 3 atmospheres) for a limited time |
| 5 bar ≈ 5 atm (≈ 40 m) | Showering is possible | The watch has been tested for water resistance up to 5 bar, which corresponds to the pressure of an assumed water column of 50 meters. This makes it suitable for everyday use such as B. bathing, showering or washing hands. |
| 10 bar ≈ 10 atm (≈ 90 m) | The watch can be used for swimming | The watch has been tested for water resistance up to 10 bar, which corresponds to the pressure of an assumed water column of 100 meters. This makes it suitable for z. B. Frequent swimming or snorkeling. |
| 20 bar ≈ 20 atm (≈ 190 m) | Diving watch | The watch has been tested for water resistance up to 20 bar, which corresponds to the pressure of an assumed water column of 200 meters. Watches in this group are suitable , for example, for snorkeling and device- free freediving at shallow depths. |
The meter specification does not refer to a diving depth, but to the test pressure that was used as part of the water resistance test. (ISO 2281) According to a judgment by the Frankfurt am Main Higher Regional Court, test pressure specifications in meters are deliberately misleading advertising statements. This information is therefore not permitted. Instead, information such as “waterproof to 3 atm” or “waterproof to 3 bar” should be used.
Limitations on watches
When swimming or under a jet of water (e.g. when showering or washing hands) pressure peaks can occur. The watch is stressed significantly more at the affected areas than the immersion depth would suggest. It is only possible to speak of a watertight watch from the classification 5 bar / 50 m (showering possible). From the classification 10 bar / 100 m , the watch can also be used while swimming.
Watertightness is not a permanent property, as the built-in sealing elements deteriorate in their function and in daily use or can be damaged by impact and fall. It is therefore advisable to carry out maintenance and check the seals and leaks every one to two years.
If a watch is exposed to large differences in temperature, e.g. when sunbathing and then jumping into cooler water, condensation can form in the case. This does not have to mean a water leak, but the moisture must be removed immediately.
Salt water causes increased corrosion - also of rubber seals - of every watch, including diving watches. Therefore, rinsing with fresh water is recommended after being in salt water.
Technical Devices
In the case of technical devices and especially measuring instruments , even a small amount of moisture inside - which can also result from condensation - can impair the function or cause measurement errors . Therefore, for more sophisticated devices, a limit is specified for the humidity and also for the conditions during storage. Electrical contacts in particular are at risk, which can result in leakage currents or the failure of magnetic contacts .
For electrotechnical installations or electronic devices that are used industrially, the so-called "IP protection classes" according to DIN EN 60529 and DIN 40 050 Part 9. The associated IP code consists of a two-digit combination that indicates the respective degree of protection, e.g. B. IP54. The first digit specifies the degree of protection for contact and foreign object protection (0–6), the second digit the protection against water and moisture (0–8).
Meaning of the first digit of the IP protection class
The first digit indicates how resistant the housing is to foreign objects. There are the following six levels:
- 0 - No protection.
- 1 - Protected against solid foreign bodies with a diameter of 50 mm or more.
- 2 - Protected against solid foreign objects with a diameter of 12.5 mm or more.
- 3 - Protected against solid foreign objects with a diameter of 2.5 mm or more.
- 4 - Protected against solid foreign bodies with a diameter of 1.0 mm or more.
- 5 - Protected against dust in harmful quantities.
- 6 - Dustproof.
Meaning of the second digit of the IP protection class
The second digit indicates how waterproof the case is. There are eight levels here.
- 0 - No protection.
- 1 - Protection against dripping water.
- 2 - Protection against falling dripping water when the housing is inclined up to 15 °.
- 3 - Protection against falling spray water up to 60 ° from the vertical.
- 4 - Protection against splashing water on all sides.
- 5 - Protection against water jets (nozzle) from any angle.
- 6 - Protection against powerful water jets.
- 7 - Protection against temporary immersion.
- 8 - Protection against permanent immersion.
Example of protection class IP68 : For the meaning of protection class IP68, let's look at the two digits one after the other. The first digit, the six, means according to the first table: The device is dustproof. The second digit, the eight, means according to the second table: Protection against permanent immersion. It follows that a device with protection class IP68 is dust and waterproof.
Clothing and textiles
Garments (and also some shoes), if they are not made of 100% waterproof material, are often made waterproof by impregnation (spraying), which has to be renewed periodically.
DIN EN 20811: 1992, also known as ISO 811, regulates the way in which the resistance to the penetration of water is determined. The following “hydrostatic water pressure test” must be carried out: The outside of the material is exposed to water. The water pressure starts at zero and increases by 10 mm per second, the time is measured until the third drop can be seen on the top, or the pressure corresponding to the time.
According to the European standard EN 343: 2003 ("protective clothing against rain"), a product with a water column from 800 mm is "waterproof (class 2)" and from 1300 mm "waterproof (class 3)". The Eidgenössische Materialprüfanstalt (EMPA) in St. Gallen, Switzerland assumes that a functional material is waterproof from a water column of 4,000 mm. When sitting on a damp surface, a pressure is built up that corresponds to a water column of approx. 2,000 mm. When kneeling in a crouch, a water column of approx. 4800 mm presses on the clothing. Materials such as Gore-Tex , Texapore O2 or Sympatex have a water column of 10,000 mm to 30,000 mm.
Shoes
Shoes are made hydrophobic and therefore water-repellent by caring for them with shoe polish . However, due to the seams and the flexing movement when walking, every leather shoe becomes water-permeable at some point. Only plastic or rubber can provide permanent protection, but is less comfortable to wear due to the lack of breathability (see rubber boots , ski boots and vapor barrier ). Membranes such as B. Sympatex, can be incorporated into shoes and make them waterproof, and depending on the membrane laminate and the temperature gradient, a certain breathability is maintained.
Bags, packs and rucksacks
For various water sports , but also for the outdoor use of entertainment electronics or cell phones, waterproof bags and pack sacks are suitable to keep moisture and dirt particles away. Waterproof bicycle bags are made of polyester or Cordura fabric coated with plastic and the seams are welded to improve tightness.
However, there is no standardized classification for the waterproofness of bags. As an aid, some manufacturers test their products according to the international industrial standard IEC 60529 (see protection class ), while others develop their own classifications with the help of typical application examples in order to create transparency with regard to the possibilities and limits of the use of waterproof bags.
House building
In house construction, the roof serves to protect against precipitation, but does not have to be waterproof. It is sufficient if the shape of the roof tiles allows the water to flow downwards. Penetration of small water or ice particles is only to be expected in very strong winds or so-called drifting snow . On the other hand, waterproofing a flat roof is more difficult.
Individual evidence
- ^ Helmut Kahlert , Richard Mühe , Gisbert L. Brunner , Christian Pfeiffer-Belli: wrist watches: 100 years of development history. Callwey, Munich 1983; 5th edition, ibid 1996, ISBN 3-7667-1241-1 , p. 506.
- ↑ The drop of water in the waterproof watch. In: Deutsche Uhrmacher-Zeitung. 1943, pp. 148-150.
- ↑ Infringement of competition: Misleading advertisement for a wristwatch with reference to water resistance. Judgment of the OLG Frankfurt 6th civil senate of April 10, 2008, AZ 6 U 34/07.
- ↑ Ortlieb.de: Materials from the manufacturer Ortlieb. ( Memento from April 26, 2014 in the Internet Archive ) Manufacturer's description. Retrieved April 25, 2014.
- ↑ Ortlieb.de: 2D and 3D high-frequency welding. ( Memento from April 26, 2014 in the Internet Archive ) Manufacturer's description. Retrieved April 25, 2014.
- ↑ Aquapac.de: Water resistance test criteria of the Aquapac brand. aquapac.de. Retrieved April 25, 2014.