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Defense Standard 00-035 Part 3: Climatic Environmental Testing

The Defense Standard (DEF STAN) 00-035 part 3 evaluates equipment subjected to environmental climatic, mechanical, and chemical conditions. As an ISO-17025 accredited compliance test lab, we realize the importance of environmental climatic testing. Meeting the environmental DEF STAN 00-035 Part 3 requirements can be difficult. We understand the challenges and guide companies through the process. 

When products do not meet specific requirements, Keystone Compliance assists with the troubleshooting process. We create an accurate test plan to eliminate expensive over-testing. Lastly, Keystone’s engineers proudly take a consultative approach throughout the entire test program.

Request a quote to learn why we are one of the fastest-growing compliance test labs in the country. Contact us to receive more information on DEF STAN 00-035 Part 3 environmental testing.

Summary of DEF STAN 00-035 Part 3

DEF STAN 00-035 Part 3 evaluates the ability of a material to withstand the effects of specific climatic environments. Though this standard reproduces the effects of relevant environments. However, the defensive standard 00-035 part 3 does not necessarily duplicate the actual environmental conditions.

Within this standard, the test methods are grouped into sections relating to commonly encountered environments. The groups consist of mechanical, climatic, and chemical.

DEF STAN 00-035 is generally applicable to packages, materials, and subcomponents.

This page will specifically cover the climatic environmental testing portion of the defensive standard 00-035 part 3. Please follow the links below for more information on mechanical or chemical environmental testing.



DEF STAN 00-035 Part 3: CHEMICAL

DEF STAN 00-035 Part 3 General Test Procedures

For many test procedures in DEF STAN, the test specimen must be pre-conditioned. All conditioned specimens must begin the test in the condition when in the natural environment.

When no other conditions are specified, but where the environment needs to be controlled, the conditions below are used.

Temperature: 20 C

Air Pressure: 101.3 kPa

Relative Humidity: 65%

When test conditions are specified, the test facility conditions fall within the following ranges below. Variations in temperature and humidity are kept to a minimum. For large specimens, the temperature range is extended beyond the specified limits below.

Temperature: 15 C to 35 C

Air Pressure: 86 kPa to 106 kPa

Relative Humidity: 25% to 75%

Climatic Testing

Temperature Testing

CL1 – Constant High Temperature and Low Humidity. Constant high temperature and low humidity testing evaluate the integrity of a material when subjected to constant hot and dry environments.

Test CL2 now incorporates both the constant hot and dry test procedure that previously existed as Test CL1.

CL2 – High Temperature and Low Humidity. Units subjected to this test must survive and operate in hot and dry conditions.

Cyclic temperature testing is intended to simulate the thermal environment that results from exposure to natural elements. The cycles are based on a 24 cycle. Fixed temperature testing replicates the highest typical temperature. This test excludes fluctuations found in the natural environment.

CL4 – Constant Low Temperature. CL4 testing determines the ability of a material to operate in constant low-temperature environments.

CL5 now includes both constant cold and diurnal cyclic testing.

CL5 – Low-Temperature. DEF STAN 00-035 Part 3 Low-temperature testing determines the ability of a material to survive and operate in cold environments.

Similar to CL2, cyclic testing is intended to simulate exposure to natural elements. Fixed temperature testing replicates the lowest typical temperature. This excludes fluctuations found in the natural environment.

CL6 – High Humidity and High Temperature. High humidity testing evaluates equipment integrity when in warm humid environments. This test applies to material directly exposed to a naturally warm, humid environment. These are typically found in wet tropical areas.

This test provides information on cyclic and fixed humidity testing similar to those in CL2 and CL4.

CL7 – Constant High Temperature and High Humidity. Constant high temperature determines a material’s integrity when subjected to constant warm and wet environments.

CL6 now incorporates both the constant hot and humid as well as diurnal cyclic tests that exist in CL6.

CL11 – Pressure and Temperature. This test assesses the effect of material exposure to pressure and combined pressure-temperature conditions. The pressure and temperature test encompasses both static and dynamic variations in air pressure. These are combined with static and dynamic variations in temperature.

CL11 replaces several procedures that existed in a previous version of this standard. These consist of CL11, CL12, CL15, CL20, and CL21.

Thermal Shock Testing

CL14 – Thermal Shock and Rapid Rate of Change in Temperature. Thermal shock testing determines the ability of a material to survive and operate when exposed to a rapid change in temperature. The test is used to simulate rapid changes in temperature in air and rapid temperature changes when transferred from air to water.

This test utilizes either one or two chambers. When using one chamber, the procedure must be capable of achieving rapid temperature change. When using two chambers, the shock is achieved by transferring the specimen from one chamber to the other.

Altitude Testing

CL15 – Air Pressure. This test evaluates the effects on the material, including packages, of exposure to air pressure above standard atmospheric conditions. Materials can experience changes in air pressure in the following ways:

  • Gat tight citadels of surface ships
  • Submarine compartments while submerged
  • In aircraft compartments when subjected to ground pressure.

CL20 – Rapid Change of Pressure. The purpose of this test is to demonstrate the ability of a material to survive changes in air pressure. These changes in air pressure are associated with the rapid climb and descent of guided weapons and high-performance aircraft.

Test procedure CL11 now supersedes tests CL12, Cl15, CL20, and CL21.

CL21 – Low Air Pressure and Air Transportation. Low air pressure testing assesses the effect on the material of exposure to low pressure and air transportation conditions. This test applies to:

  • Material carried or installed in pressurized or unpressurized regions of service aircraft.
  • Material stored and operated at high ground elevations.
  • Material contained in enclosures with internal atmospheres below standard atmospheric pressure.
  • Demonstrate compliance of material with low-pressure requirements.

Test procedure CL11 now supersedes tests CL12, Cl15, CL20, and CL21.

Icing/Freezing Rain Testing

CL23 – Impact Icing. The DEF STAN 00-035 impact icing test evaluates equipment integrity when exposed to impact icing conditions. There are three main reasons for performing this test:

  • To demonstrate the performance of exposed forward-facing material during flight through ice-forming conditions.
  • To demonstrate the performance of an anti-icing or de-icing system.
  • To ensure ice accretion or subsequent shedding of ice does not present a hazard to the safe operation of an aircraft or other deployed material.

To perform this test, the unit is placed in an icing tunnel. Additionally, the device is mounted at the angles of incidence. The specimen is operated at the phase of the test that is most adverse.

At the end of the test, the unit is examined for any damage.

CL24 – Freeze Thaw. The purpose of freeze-thaw testing is to evaluate the integrity of a material when it is subjected to cycles of freezing and thawing. The repeated cycles can produce an alternating mix of ice and water. This may cause induced stress or interference between moving parts.

The freeze-thaw test applies to materials that can experience temperature cycling. These conditions are most of the time found in milder climates.

The number of cycles performed for this test is chosen before testing. The unit under testing is sprayed with water to produce ice accreditation up to a specified depth. This is usually between 3mm to 6mm deep.

Sand and Dust Testing

CL25 – Dust and Sand. The dust and sand compliance test procedure assesses the effects of dust and sand-laden atmospheres. More specifically, the procedure applies to any material that can be carried or located externally.

This DEF STAN 00-035 method is generally concerned with wind-blown dust and wind-blown sand conditions. However, it also includes procedures for settling or turbulent dust.

There are two primary modes by which dust or sand degrade material.

The first is abrasive erosion of exposed surfaces. Particles moving at high speeds can act as damaging abrasives on surfaces. The degree of surface abrasion will depend on the velocity of the particles relative to the surface.

The second is penetration into the material. Once any protection has been breached, the penetration of material can exercise several damaging results. These include jamming and increased friction of mechanisms.

Water/Rain Testing

CL16 – Wind. The purpose of wind testing is to determine the ability of a material to maintain its integrity when exposed to wind conditions. The DEF STAN wind test applies to material deployed at ground locations or on naval platforms. This test is used when satisfactory structures cannot be designed using a recognized code of practice.

The wind tests include four procedures. Two of these tests are intended for the evaluation of material operation performance. The third test procedure is applicable for the evaluation of material survival. The last procedure applies to the evaluation of the performance of cooling systems.

CL27 – Driving Rain. The DEF STAN 00-035 driving rain test evaluates the integrity of a material to exposure to driving rain. The unit under testing will remain operational during or following the exposure. This driving rain test does not evaluate the erosion resistance of a material.

Each nozzle will deliver a cone of water droplets. The distance of the nozzles and the direction of the spray are specified to provide a consistent intensity of the test. Specimens required to operate during exposure to driving rain are operated at the necessary stages of the test.

CL28 – Water Drip. Water drip testing assesses material integrity when subjected to water drips. Dripping water comes from overhead surfaces and results from condensation in unconditioned avionics bays of aircraft.

In most cases, material drip-proofness is established from consideration of driving rain or immersion. The water drip test is also considered if the material is in a different operating state when subjected to water.

The effectiveness of any protection is assessed by a visual inspection of water ingress. If the material is required to operate, a necessary performance evaluation is conducted.

CL29 – Immersion and Pressurized Water Chamber. Immersion and pressurized water chamber testing determine the capacity of a material to operate while it is submerged. This portion of the DEF STAN 003-035 standard is conducted either using a water tank or a pressurized water chamber.

The immersion test is performed with the material arranged in each orientation in which it is most likely to become immersed.

If the unit under testing is normally able to recover from dripping water conditions, then a recovery period is utilized. This recovery period does not normally exceed 24 hours.

The recommended test severities can range from 30 minutes of immersion to typically less than two hours. The water temperature is stated to be less than 35 C. Lastly, the submersion depth is generally around 1.5 m.

Expert DEF STAN 00-035 Part 3 Environmental Climatic Test Laboratory

Keystone Compliance has a full lab of test equipment which permits us to provide short lead times on scheduling. In addition to environmental defense standard testing, Keystone has a full scope of expertise including EMC/EMI, shielding effectiveness, and package testing. 

Have a question about DEF STAN 00-035 part 3 testing? Contact us to discuss the best course of action. Request a quote to see why so many companies trust Keystone for their environmental regulatory compliance test needs.

For more information on Defense Standard regulatory compliance testing, please follow the links below:



DEF STAN 00-035 Part 3: CHEMICAL