What Is Rain?
The rain test is one in which the sample is exposed to artificial rain at a defined flow rate, drop size and wind speed. Unlike IP tests, it also includes the effect of wind.
Purpose of Rain
The purpose is to verify that equipment operating outdoors prevents water ingress from rain and wind-driven water, and maintains its function.
Which Products Is Rain Applied To?
- Defence and field equipment
- Aviation exterior components
- Outdoor electronic enclosures
- Vehicle-mounted equipment
In Which Sectors Is Rain Used?
Standards Related to Rain
- MIL-STD-810 Method 506
- RTCA DO-160 Section 10
- IEC 60529degree of protection provided by enclosures (IP code) test
Rain Conditions
- rainfall rate
- Defined in the standard; Typically 1.7 mm/min in MIL-STD-810
- wind speed
- Defined in the standard; drops gain a horizontal component
- Droplet size
- Standard defined range
- Time
- Defined time for each surface
Equipment for Rain
- Rain test chamber
- Spray nozzle array
- Wind-generating fan
- Flow rate and speed measurement
Sample Requirements for Rain
- The sample must be placed in its actual mounting orientation
- Function and insulation must be measured before the test
- All surfaces must be exposed
- The enclosure interior must be clean and dry
Duration of Rain
Depends on the number of surfaces; typically half to one working day.
Rain Procedure
- 1Rainfall rate, drop size and wind speed are set.
- 2The sample is placed in the chamber.
- 3Rain is applied for the defined duration onto each surface.
- 4The sample surface is dried.
- 5The enclosure is opened to check for water ingress.
- 6Function and insulation are re-measured.
Rain Acceptance Criteria
The acceptance criterion is defined in the specification: no ingress of water into the enclosure in a quantity that would disrupt function, and continuity of function.
Evaluation of Results
Due to the wind effect, gasket and cover joints are critical points. The location of water ingress is recorded for design improvement.
Rain Report
- Standard applied
- Rainfall rate, drop size, wind speed and duration
- Exposed surfaces
- Water ingress observation and functional results
Accreditation
EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.
Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.
Scope and authorisationsRelated Regulations
- Defence and aviation equipment specifications
Environmental and Climatic Testing — What Does This Testing Field Cover?
The section below describes the field that the Rain test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.
Environmental testing shows whether a product withstands ambient factors such as temperature, humidity, pressure, solar radiation, dust, water and corrosive atmospheres. The aim is not to break the product but to bring forward, in ACCELERATED form, the conditions it will meet over its life.
Test profiles are derived from the product's real exposure, and that derivation is the actual engineering work of the field. A device operating in an enclosed office and one mounted on a pole are not tested with the same profile. The IEC 60068 series defines general methods, MIL-STD-810 military profiles, RTCA DO-160 aviation profiles and the ISO 16750 series location-based automotive profiles. A test applied without a profile selection produces both unnecessary cost and false confidence.
Temperature tests simulate three separate phenomena and all three produce different failure modes. Steady high/low temperature tests whether the material can operate at that temperature. Temperature CYCLING creates fatigue at joints between materials with different expansion coefficients — solder cracks appear here. Thermal SHOCK intensifies this effect through an abrupt transition.
There is a distinction in humidity testing too. Steady damp heat shows the diffusion of moisture into the material and its effect on insulation properties. Cyclic damp heat creates condensation: water droplets form on the cooling surface, and this is far more aggressive than dry humidity. Water ingress into enclosures, increased leakage current and corrosion usually appear in the cyclic test.
Dust and water protection is a separate body of work and is expressed by the IP code. The point to note here is that an IP test is not a DURABILITY test: it shows that protection is provided under defined and short-duration conditions, not resistance to long-term immersion or pressure washing.
The most common mistake in this family is translating a test result directly into a LIFE PREDICTION. Accelerated tests are designed for comparison and design verification; a reliable conversion between hours in a chamber and years in the field can only be established with a material-specific acceleration model calibrated against field data.
Functional monitoring determines the value of the test. Keeping a product in a temperature chamber and then switching it on does not show what happened DURING the test. In critical applications the product is operated throughout the test and its parameters are monitored; intermittent faults that appear and disappear can only be caught this way.
Method groups in this field
Temperature
Dry heat, cold, change of temperature and thermal shock; steady and cyclic profiles.
Humidity
Steady damp heat and cyclic damp heat; cycles with condensation are more aggressive.
Water and dust
IP protection tests: dripping, spraying, jets, immersion and dust tightness.
Radiation and ageing
Accelerated ageing by xenon arc and fluorescent UV, solar radiation simulation.
Pressure and altitude
Low pressure (altitude) and rapid pressure change tests.
Corrosive atmosphere
Salt spray, mixed flowing gas corrosion (simulating industrial atmospheres), mould and fungus tests.
Commonly confused in this field
- Test duration cannot be converted into field life; a conversion made without an acceleration model is misleading.
- Temperature cycling and steady temperature produce different failure modes; neither replaces the other.
- If the product is not operated during the test, intermittent faults remain invisible; functional monitoring determines the value of the test.
- IP protection is not evidence of durability; it shows protection under defined and short-duration conditions.
- A test applied without profile selection both increases cost and gives false confidence.
- The mounting and orientation arrangement affects the result; the report must document it.
Which decisions these results support
- Design verification and qualification
- Declaration of the protection class and operating temperature range
- Reproducing field failures in the laboratory and root cause analysis
- Supplier component approval
- Decisions on warranty period and storage conditions
Related Tests
Frequently Asked Questions About Rain
According to which standard is Rain made?
Rain is executed in scope MIL-STD-810 Method 506, RTCA DO-160 Section 10 and IEC 60529. The limit values and acceptance criteria to be applied are defined in the product standard; The version valid for your product is confirmed in writing at the offer stage.
Which products does Rain apply to?
Mainly applied to Defence and field equipment, Aviation exterior components, Outdoor electronic enclosures and Vehicle-mounted equipment. Whether your product is included in the scope is determined by examining its technical specifications and intended use.
Under what conditions is Rain done?
The determining parameters are: rainfall rate — Defined in the standard; Typically 1.7 mm/min in MIL-STD-810, wind speed — Defined in the standard; drops gain a horizontal component and Droplet size — Standard defined range. The full terms are in the "Test Conditions" section on the page and vary depending on the product standard.
What kind of sample is needed for Rain?
The sample must be placed in its actual mounting orientation, Function and insulation must be measured before the test and All surfaces must be exposed. The number of samples is determined according to the product standard and the scope to be reported.
How long does Rain take?
Depends on the number of surfaces; typically half to one working day. This duration belongs to the experiment itself; sample preparation, queuing and reporting are also evaluated. A realistic schedule for your product is given in the offer.
What is the Rain result called "appropriate"?
The acceptance criterion is defined in the specification: no ingress of water into the enclosure in a quantity that would disrupt function, and continuity of function.