What Is Low Pressure?
The low pressure test is one in which the sample is held at a pressure below atmospheric to assess function, discharge (corona) and sealing behaviour. It is defined as method M in IEC 60068-2-13.
Purpose of Low Pressure
The purpose is to verify the adequacy of electrical clearances, cooling performance and sealing at low pressure.
Which Products Is Low Pressure Applied To?
- Aviation and high-altitude electronics
- High-voltage equipment
- Pressurised enclosures
- Battery systems
In Which Sectors Is Low Pressure Used?
Standards Related to Low Pressure
- IEC 60068-2-13series of environmental testing methods test
- RTCA DO-160 Section 4
- MIL-STD-810 Method 500
Low Pressure Conditions
- Pressure
- Absolute pressure defined in the specification
- Time
- Holding time defined in the standard
- electrical condition
- Corona and discharge are monitored in high voltage equipment
- Temperature
- If necessary, apply combined
Equipment for Low Pressure
- Vacuum chamber
- Pressure measurement system
- Partial discharge measurement setup
- Function monitoring
Sample Requirements for Low Pressure
- The sample must be installed in its typical mounting configuration
- Clearance distances must be documented
- Function must be checked before the test
- Safety precautions must be taken if high voltage is to be applied
Duration of Low Pressure
Depends on the duration defined in the specification; typically hours.
Low Pressure Procedure
- 1The sample is placed in the chamber and initial measurements are taken.
- 2The pressure is reduced to the defined value.
- 3Operating voltage is applied and discharge monitored if required.
- 4The conditions are maintained for the defined duration.
- 5Pressure is returned to ambient and final measurements are taken.
Low Pressure Acceptance Criteria
The acceptance criterion is defined in the specification: continuity of function, no partial discharge or arcing, and no leakage.
Evaluation of Results
Air's dielectric strength decreases at low pressure, so the adequacy of clearance distances is revealed by this test.
Low Pressure Report
- Standard applied
- Pressure, duration and electrical conditions
- Discharge observation
- Function 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
- Aerospace equipment requirements
- High-voltage equipment standards
Environmental and Climatic Testing — What Does This Testing Field Cover?
The section below describes the field that the Low Pressure 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 Low Pressure
According to which standard is Low Pressure made?
Low Pressure is executed in scope IEC 60068-2-13, RTCA DO-160 Section 4 and MIL-STD-810 Method 500. 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 Low Pressure apply to?
Mainly applied to Aviation and high-altitude electronics, High-voltage equipment, Pressurised enclosures and Battery systems. Whether your product is included in the scope is determined by examining its technical specifications and intended use.
Under what conditions is Low Pressure done?
The determining parameters are: Pressure — Absolute pressure defined in the specification, Time — Holding time defined in the standard and electrical condition — Corona and discharge are monitored in high voltage equipment. 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 Low Pressure?
The sample must be installed in its typical mounting configuration, Clearance distances must be documented and Function must be checked before the test. The number of samples is determined according to the product standard and the scope to be reported.
How long does Low Pressure take?
Depends on the duration defined in the specification; typically hours. 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 Low Pressure result called "appropriate"?
The acceptance criterion is defined in the specification: continuity of function, no partial discharge or arcing, and no leakage.