Altitude Testing Explained: Pressure, Temperature, MIL-STD-810H Method 500.6 and IEC 60068-2-13

Date: 07/04/2026 Categories: Technical articles Views: 11098

Low Pressure + Temperature + Test Tailoring

Altitude Testing Starts with Pressure—not an Altitude Label

Use this guide to distinguish steady low-pressure exposure from operational altitude, rapid decompression and combined temperature-pressure testing. It explains how MIL-STD-810H Method 500.6 and IEC 60068-2-13 differ, what must be tailored, and what chamber capability should be verified before a test plan is approved.

MIL-STD-810HFour low-pressure procedures under Method 500.6

IEC 60068-2-13Test M for specimens exposed to low air pressure

Selection principleSpecify pressure, temperature, rate, load and operation

Altitude testing in one minute

Altitude testing reduces the chamber's absolute pressure to reproduce the air density associated with transport, storage or operation at elevation. Temperature may be controlled at the same time when the product's real environment or governing procedure requires it. The test can expose cooling limitations, electrical arcing, seal leakage, enclosure deformation, lubricant behavior and functional instability that remain hidden at normal atmospheric pressure.

Altitude is a referenceThe chamber controls pressure. A height in metres or feet is an approximate way to communicate that pressure under a selected atmospheric model.

The profile is not universalTarget pressure, temperature, transition rate, dwell, specimen state and acceptance criteria come from the applicable requirement and test tailoring.

Capability is procedure-specificA chamber that holds steady low pressure may not perform rapid or explosive decompression, powered monitoring or coupled thermal profiles.

Procurement warning: “Up to 30,000 m” does not define a test system. Ask for the absolute-pressure endpoint, controllable transition rate, temperature-pressure operating envelope, loaded workspace, interfaces, records and safety functions.

Absolute pressure, gauge pressure and simulated altitude

Low-pressure environmental testing should be specified in absolute pressure—normally kPa absolute, hPa or mbar. Gauge pressure describes pressure relative to the surrounding atmosphere and can therefore create ambiguity when used for altitude simulation. A requirement of 11.6 kPa means approximately 11.6 kPa absolute, not “11.6 kPa below atmospheric pressure.”

Pressure-to-altitude conversion is useful for planning, but it varies with the atmospheric model and assumed conditions. The pressure value and tolerance stated by the governing document should control the test.

Approximate altitude	Reference absolute pressure	Planning use
Sea level	101.3 kPa	Ambient baseline
3,000 m / 9,840 ft	About 70.1 kPa	High-ground operation or transport
4,500 m / 14,760 ft	About 57.5 kPa	Severe terrestrial elevation
7,620 m / 25,000 ft	About 37.6 kPa	Aircraft/cargo profile reference
12,192 m / 40,000 ft	About 18.8 kPa	High-altitude aviation reference
15,240 m / 50,000 ft	About 11.6 kPa	Air-transport and decompression reference
30,480 m / 100,000 ft	About 1.0 kPa	Very-low-pressure capability reference

These values are approximate planning references, not a replacement for the pressure table, tolerance and atmospheric model cited by the approved test procedure.

MIL-STD-810H Method 500.6: four procedures with different equipment demands

MIL-STD-810H is an environmental-engineering and laboratory-test standard. Its official scope emphasizes tailoring realistic environmental conditions to the materiel life cycle rather than imposing one universal profile. Method 500.6 therefore needs the test authority to select the applicable procedure, pressure, temperature, duration, transition and item configuration.

Procedure	What it evaluates	Chamber capability to verify
I — Storage / Air Transport	Survival of the item in its storage or transport configuration during low-pressure exposure	Pressure endpoint, controlled reduction/recovery, dwell stability, packaging clearance and post-test inspection
II — Operation / Air Carriage	Performance while the item operates at the selected pressure and associated condition	Powered feedthroughs, monitoring channels, heat-load capacity, observation and traceable data
III — Rapid Decompression	Response to a defined fast pressure loss representing a relevant life-cycle event	Valve and vacuum-system flow, start/end pressure, timed transition, data rate and safety interlocks
IV — Explosive Decompression	Response to the shortest justified decompression event for the applicable platform or compartment	Project-specific high-flow architecture, containment, structural design, high-speed recording and hazard controls

Important: Procedures III and IV are not obtained merely by setting a lower final pressure. Their pressure-change time is part of the event. Standard controlled evacuation equipment must not be represented as rapid/explosive-decompression capable unless the complete transition is demonstrated.

IEC 60068-2-13:2021 Test M

IEC 60068-2-13:2021 specifies low-air-pressure test methods for specimens that may encounter reduced pressure during transport, storage or service. The 2021 fifth edition aligns its severities with the IEC 60721 family and adds guidance on selecting exposure duration.

Use IEC 60068-2-13 when the requirement cites Test M or an IEC low-pressure severity. Do not automatically replace it with a MIL-STD-810H procedure: the documents have different structures, tailoring practices and acceptance contexts. When temperature, humidity and low pressure must be combined, verify the specific combined-environment method and the chamber's permitted operating envelope rather than assuming Test M alone defines the full sequence.

Question	MIL-STD-810H Method 500.6	IEC 60068-2-13:2021
Primary framework	Life-cycle environmental tailoring for materiel	Standardized Test M low-air-pressure method
Low-pressure procedures	Storage/transport, operation, rapid decompression and explosive decompression	Low-air-pressure exposure using the applicable selected severity and duration
Pressure profile	Tailored to platform, life-cycle profile and requirements	Selected from or defined with the applicable IEC/product requirement
Powered operation	Depends on selected procedure and approved test plan	Depends on specimen requirement and referenced specification
Rapid/explosive decompression	Addressed by Procedures III and IV	Not a substitute for Method 500.6 decompression procedures
Pass/fail	Defined by materiel requirements and test plan	Defined by the relevant product specification or agreed acceptance criteria

Pressure, altitude and temperature relationship

Altitude testing relationship between absolute pressure temperature and simulated height

Absolute pressure is the controlled test variable; simulated altitude is a planning reference, while temperature follows the approved test profile.

When temperature and pressure must run together

Reduced air density changes heat transfer and electrical behavior. A powered electronic assembly can run hotter at altitude even when the air temperature remains unchanged. Seals, lubricants and materials can also respond differently when temperature and pressure change together. Combined control is justified when the real service condition, failure mechanism or governing procedure requires the interaction.

Powered electronicsObserve component temperature, voltage regulation, signal integrity and protection behavior while reduced convection limits heat removal.

High-voltage assembliesEvaluate insulation margin and discharge risk using the approved electrical-safety procedure and instrumented specimen.

Sealed equipmentCheck enclosure deformation, leakage, venting, display fogging and post-test function through the pressure cycle.

Avionics and UAV systemsRun operating checks at the temperature-pressure points defined for the equipment category and platform.

Automotive electronicsEvaluate high-altitude function under the climatic and electrical conditions referenced by the applicable vehicle/component requirement.

BatteriesApply the cited transport or product procedure with a documented hazard assessment and appropriate containment, monitoring and emergency controls.

Do not combine stresses by assumption. If the requirement specifies separate temperature conditioning and low-pressure exposure, reproduce that sequence. Simultaneous operation can create a different stress and must be authorized by the governing plan.

Related standards: identify the exact clause before configuring equipment

Document	Relevant use	Procurement caution
RTCA DO-160G Section 4	Temperature and altitude conditions for airborne equipment	State the applicable category and complete profile; do not claim blanket DO-160 compliance
UN Manual of Tests and Criteria, 38.3 T.1	Lithium cell/battery altitude simulation for transport	T.1 uses ≤11.6 kPa for at least 6 h at 20 ±5°C; battery safety and the rest of 38.3 remain separate requirements
IEC 60068-2-39	Combined temperature or temperature/humidity with low air pressure	Check the cited edition, sequence and severity rather than treating it as Test M
GB/T 2423.21	Chinese low-air-pressure environmental test method	Use the edition required by the customer or laboratory
GJB 150.2A	Low-pressure (altitude) testing for the applicable Chinese military project	Confirm procedure, profile, reporting and project authorization
ASTM D6653 / ISO 2873	Reduced-pressure testing for packaging or complete filled transport packages	Package size, load, pressure cycle and observation requirements govern chamber selection

Chamber selection checklist

The right chamber is defined by the complete test profile, not by nominal litres or ultimate pressure alone.

Selection item	What to specify	Why it changes the design
Working space	Loaded specimen envelope, mass, fixture, shelves, cable routing and service clearance	Determines usable airflow, access, structure and pumping volume
Pressure	Starting pressure, endpoint, tolerance, dwell, reduction and recovery rates	Sizes pumps, valves, piping, control range and pressure sensor
Temperature	High/low endpoints, rate, stabilization and simultaneous pressure points	Determines refrigeration, heating and thermal compensation under reduced density
Powered load	Voltage, current, heat output, operation sequence and monitored parameters	Affects feedthroughs, heat-load capacity, sensors and safety
Decompression	Procedure, start/end pressure and maximum transition time	Conventional evacuation may not satisfy rapid or explosive decompression
Data	Temperature, absolute pressure, specimen channels, sampling rate, CSV and communication protocol	Defines controller, acquisition and report traceability
Safety	Stored energy, chemistry, vent gas, flammables, pressure release and emergency response	Determines containment, detection, interlocks and permitted specimen operation
Acceptance	Calibration points, load condition, FAT duration, third-party witness and report language	Prevents disagreement after manufacture and before shipment

For combined thermal and altitude work, review the DERUI altitude temperature test chamber. For the full product category and alternative configurations, compare the altitude test chamber range.

Build the test plan before the chamber program

Identify the authority.
Record the exact standard edition, method, procedure/category, product requirement and customer deviations.
Define the specimen state.
State packaging, orientation, load, powered operation, heat output, monitoring and preconditioning.
Write the complete profile.
List temperature and absolute pressure setpoints, rates, dwell, cycles and permitted interruptions.
Define observations.
Specify electrical, thermal, mechanical, leakage and visual parameters before, during and after exposure.
Approve safety controls.
Complete the hazard review, interlock matrix, emergency response and access restrictions.
Agree on evidence.
Fix calibration points, sampling, curve export, deviations, photographs, FAT and final report requirements.

Good test evidence connects five items: the approved requirement, chamber identification, calibrated instruments, recorded environmental profile and specimen result. A controller screenshot alone does not demonstrate full conformity.

Common failure modes altitude testing can reveal

Thermal overloadReduced convection raises internal component temperature or changes protection behavior during powered operation.

Electrical dischargeReduced dielectric strength can expose insulation clearance or high-voltage design weaknesses.

Seal and enclosure responseDifferential pressure can cause leakage, deformation, venting, window fogging or damaged seals.

Fluid and lubricant behaviorLower pressure and temperature can affect evaporation, viscosity, bubbles and fluid delivery.

Sensor or control driftPressure-sensitive components, cooling control and sampled signals can deviate from ambient baselines.

Packaging damageSealed packages or flexible containers can expand, leak or rupture during reduced-pressure transport simulation.

These are possible failure mechanisms, not guaranteed outcomes. Product-specific acceptance criteria must define what constitutes a failure.

Frequently asked questions

Is simulated altitude the same as vacuum?

Altitude testing uses partial vacuum to reduce absolute pressure, but “vacuum” alone does not define the environmental profile. Altitude work normally requires controlled pressure, transition, dwell and often temperature or powered operation.

Should a test requirement use metres, feet or kPa?

Record the altitude reference if it helps users understand the scenario, but program and verify the absolute pressure required by the governing document. Include tolerance and atmospheric model where applicable.

Does MIL-STD-810H Method 500.6 define one standard altitude?

No. The profile is tailored from the item life cycle, platform and approved requirement. Do not select a universal pressure, duration or rate for every item.

What is the main difference between Method 500.6 and IEC 60068-2-13?

Method 500.6 sits within MIL-STD-810H's life-cycle tailoring framework and includes four procedures, including decompression events. IEC 60068-2-13 is Test M for low-air-pressure exposure using the applicable selected severity and duration. Use whichever document the requirement cites.

Can a standard altitude chamber perform rapid decompression?

Not automatically. Rapid decompression requires the specified starting and ending pressures to be reached within the required time. Pumping capacity, valve flow, piping, chamber volume, load and data rate must be engineered and demonstrated together.

When should temperature and pressure run simultaneously?

Run them together only when the governing method, actual service environment or approved failure-mechanism analysis requires combined stress. Otherwise follow the specified separate conditioning and exposure sequence.

Does UN 38.3 T.1 require temperature-altitude cycling?

T.1 is an altitude-simulation exposure at ≤11.6 kPa for at least six hours at 20 ±5°C. It should not be confused with T.2 thermal testing or T.4 shock. The complete UN 38.3 sequence and battery safety controls remain applicable.

What information should be sent for a chamber quotation?

Send the exact standard and procedure, loaded specimen dimensions and mass, temperature-pressure sequence, decompression rate, powered interfaces, heat load, safety hazards, utilities, records and FAT requirements.

Primary references

Consult licensed/current standards and the approved product requirement for complete procedures. This article is an equipment-selection and planning guide, not a substitute for the standards.

Turn the altitude requirement into a chamber specification

Send DERUI the standard edition, procedure, specimen envelope, powered load, temperature-pressure profile, transition time, safety conditions and FAT points. The engineering review will confirm whether a standard altitude-temperature chamber or a special decompression configuration is required.

Review the Altitude Temperature Chamber

Prepare these details