IP Ratings

Degrees of Protection Provided by Enclosures (IP Code)

This standard describes a system for classifying the degrees of protection provided by the enclosures of electrical equipment, such as ruggedized handheld computers. The adoption of this classification system, wherever possible, will promote uniformity in methods of describing the protection provided by the enclosure and in the tests to prove the various degrees of protection. This standard has been prepared by the IEC Technical Committee.

Elements of the IP Code and their meanings

Ingress
Protection
IP
1st
Digit
#
2nd
Digit
#

1st Digit Degree of protection against solid objects
0non-protected
150.0 mm diameter
212.5 mm diameter
32.5 mm diameter
41.0 mm diameter
5dust-protected
6dust-tight
2nd Digit Degree of protection against water
0non-protected
1vertically dripping
2dripping (15-degrees)
3spraying
4splashing
5jetting
6powerful jetting
7temporary immersion
8continuous immersion

MIL-STD-810F Method 500.4 - Low Pressure

Low-pressure (altitude) chamber tests are performed to determine if materiel can withstand, and operate in, a low-pressure environment, and withstand rapid pressure changes. Examples of some problems that could occur as a result of exposure to reduced pressure are:

  1. Rupture or explosion of sealed containers.
  2. Change in physical and chemical properties of low-density materials.
  3. Erratic operation or malfunction of equipment resulting from arcing or corona.
  4. Overheating of equipment due to reduced heat transfer.
  5. Failure of hermetic seals.

High temperatures may temporarily or permanently impair the performance of the test item by changing the physical properties or dimensions of the material composing it. Examples of some other problems that could occur as the result of high temperature exposure are as follows:

  1. Parts binding from differential expansion of dissimilar materials.
  2. Materials changing in dimension, either totally or selectively.
  3. Gaskets displaying permanent set.
  4. Closure and sealing strips deteriorating.
  5. Fixed-resistance resistors changing in values.
  6. Electronic circuit stability varying with differences in temperature gradients and differential expansion of dissimilar materials.
  7. Transformers and electromechanical components overheating.
  8. Shortened operating lifetime.
  9. High pressures created within sealed cases.
  10. Discoloration, cracking or crazing of organic materials.

MIL-STD-810F Method 502.4 - Low Temperature

Low temperatures have adverse effects on almost all basic materiel. As a result, exposure of test items to low temperatures may either temporarily or permanently impair the operation of the test item by changing the physical properties of the material composing it. Therefore, low temperature test must be considered whenever the test item will be exposed to temperatures below standard ambient. Examples of some problems that could occur as the result of exposure to cold are:

  1. Hardening and embrittlement of materials.
  2. Binding of parts from differential contraction of dissimilar materials and the different rates of expansion of different parts in response to temperature transients.
  3. Changes in electronic components (resistors, capacitors, etc.).
  4. Stiffening of shock mounts.
  5. Cracking and crazing, embrittlement, change in impact strength, and reduced strength.
  6. Static fatigue of restrained glass.
  7. Condensation and freezing of water.

Temperature shock tests are conducted to determine if materiel can withstand sudden changes in the temperature of the surrounding atmosphere without experiencing physical damage or deterioration in performance. As a result of exposure to sudden temperature changes, operation of the test item may be affected either temporarily or permanently. Examples of problems that could occur as a result of exposure to sudden changes in temperature are:

  1. Shattering of glass.
  2. Binding or slackening of moving parts.
  3. Separation of constituents.
  4. Stiffening of shock mounts.
  5. Changes in electronic components.
  6. Electronic or mechanical failures due to rapid water or frost formation.
  7. Differential contraction or expansion of dissimilar materials.
  8. Deformation or fracture of components.
  9. Cracking of surface coatings.
  10. Leaking of sealed compartments.

Temperature shock tests are conducted to determine if materiel can withstand sudden changes in the temperature of the surrounding atmosphere without experiencing physical damage or deterioration in performance. As a result of exposure to sudden temperature changes, operation of the test item may be affected either temporarily or permanently. Examples of problems that could occur as a result of exposure to sudden changes in temperature are:

  1. Shattering of glass.
  2. Binding or slackening of moving parts.
  3. Separation of constituents.
  4. Stiffening of shock mounts.
  5. Changes in electronic components.
  6. Electronic or mechanical failures due to rapid water or frost formation.
  7. Differential contraction or expansion of dissimilar materials.
  8. Deformation or fracture of components.
  9. Cracking of surface coatings.
  10. Leaking of sealed compartments.

MIL-STD-810F Method 506.4 - Rain

The rain test is conducted to determine the effectiveness of protective covers or cases in preventing the penetration of rain, and the capability of the test item to satisfy its performance requirements during and after exposure to rain. Examples of some problems that could occur as a result of exposure of materiel to moisture and rain are:

  1. Degradation of strength.
  2. Corrosion of metals.
  3. Deterioration of surface coatings.
  4. Malfunction of electrical components.

MIL-STD-810F Method 507.4 - Humidity

Moisture can cause physical and chemical deterioration of material to include surface effects such as corrosion, and biologic growth; changes in material properties due to moisture penetration, and electrical or mechanical performance effects due to condensation. Typical problems that can result from exposure to a warm, humid environment include:

  1. Swelling of materials due to moisture absorption.
  2. Loss of physical strength.
  3. Changes in mechanical properties.
  4. Degradation of electrical and thermal properties in insulating materials.
  5. Electrical shorts due to condensation.
  6. Binding of moving parts due to corrosion or fouling of lubricants.
  7. Oxidation and/or galvanic corrosion of metals.
  8. Loss of plasticity.
  9. Accelerated chemical reactions.

MIL-STD-810F Method 510.4 - Sand and Dust

This test method is divided into two procedures. The small-particle procedure (dust, fine sand) is performed to ascertain the ability of equipment to resist the effects of dust particles which may penetrate into cracks, crevices, and joints. The blowing sand test is performed to determine whether materiel can be stored and operated under blowing and conditions without experiencing degradation of its performance, effectiveness, reliability, and maintainability due to the abrasion (erosion) or clogging effect of large, sharp-edged particles. Examples of some problems that could occur as a result of exposure of material to blowing sand and dust are:

  1. Abrasion of surfaces.
  2. Penetration of seals.
  3. Erosion of surfaces.
  4. Degradation of electrical circuits.
  5. Clogging of openings and filters.
  6. Physical interference with mating parts.
  7. Fouling of moving parts.

MIL-STD-810F Method 512.4 - Immersion

Experience has shown that a temperature differential between the test item and the water can affect the outcome (leakage) of an immersion test. Increasing the test item temperature above the water temperature for the immersion test usually includes heating of the test item to establish a pressure differential (while cooling) to determine if the seals or gaskets leak under relatively low-pressure differential, and to induce expansion/contraction of materials. Although desired, establishing a specific temperature differential for fording tests is often impractical due to the size of the materiel. Also, consider materiel adjacent to heat-producing equipment such as engines, and use temperatures indicative of actual exposure.

MIL-STD-810F Method 514.5 - Vibration

Vibration testing is performed to determine the resistance of equipment to vibrational stresses expected in its shipment and application environments. Vibration can cause:

  1. Wire chafing.
  2. Loosening of fasteners.
  3. Intermittent electrical contacts.
  4. Touching and shorting of electrical parts.
  5. Seal deformation.
  6. Component fatigue.
  7. Display / Touch Panel misalignment.
  8. Cracking and rupturing.
  9. Excessive electrical noise.

MIL-STD-810F Method 516.5 - Shock

Shock tests are performed to assure that materiel can withstand the relatively infrequent, non-repetitive shocks or transient vibrations encountered in handling, transportation, and service environments. Shock tests are also used to measure an item's fragility, so that packaging may be designed to protect it, if necessary. Mechanical shocks will excite an equipment item to respond at both forced an natural frequencies. This response, among other things, can cause:

  1. Failures due to increased or decreased friction, or interference between parts.
  2. Changes in dielectric strength, loss of insulation resistance, variations in magnetic and electrostatic field strength.
  3. Permanent deformation due to overstress.
  4. More rapid fatiguing of materials.

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