MIL-STD-202H.pdf - 第47页

MI L - S TD - 202 - 107 T ABL E I . T her m al s ho c k t es t c ond i t i o ns ( ai r ) 1 / . Te st co ndit ion N um ber of cy cl e s Te s t c o n di t i on N um ber of cy cl e s T est c o n dit ion Number of cycle s St…

MIL-STD-202-107

4.2. PROCEDURE.

4.2.1 Environmental chambers. Specimens shall be placed so that there is substantially no obstruction to the flow

of air across and around the specimen. When special mounting is required, it shall be specified. The specimen shall

be subjected to the specified test condition of table I. The first five cycles shall be run continuously. After five cycles,

the test may be interrupted after the completion of any full cycle, and the specimens allowed to return to room

ambient temperature before testing is resumed. One cycle consists of steps 1 through 4 of the applicable test

condition. Specimens shall not be subjected to forced circulating air while being transferred from one chamber to

another. Whether single or multiple chambers are used, the effective total transfer time from the specified low

temperature to the specified high temperature, or the reverse, shall not exceed 5 minutes. Direct heat conduction to

the specimen should be minimized. In the case of multiple chambers, the transfer time shall be defined as the time

between withdrawal from the low temperature chamber and introduction into the high temperature chamber or the

reverse.

NOTE: In single compartment chambers, in which the temperature extremes of steps 1 and 3 are achieved without

physical movement of the specimens, steps 2 and 4 are not applicable.

4.2.2 Liquid baths. Specimens shall be immersed in a suitable liquid that shall be approved by the qualifying

activity (see table IV), at the temperature in step 1 of the specified test condition (see table III) for the time specified in

table V. Immediately upon the conclusion of step 1, the device shall be transferred to a suitable liquid at the

temperature specified in step 2 of the specified test condition. The device shall remain at the high temperature for the

time specified in table V. These two steps, step 1 and 2, constitute one cycle of the applicable test condition. Repeat

the required number of cycles without interruption as specified in table III. Transfer time from low to high temperature

and from high to low temperature shall be less than 10 seconds.

4.3 Measurements. Specified measurements shall be made prior to the first cycle and upon completion of the final

cycle, except that failures shall be based on measurements made after the specimen has stabilized at room

temperature following the final cycle.

5. DETAILED REQUIREMENTS

5.1. Summary. The following details are to be specified in the individual specification:

a. Recovery time if other than 5 minutes (see 4.1.1).

b. Special mounting, if applicable (see 4.2).

c. Type test (air or liquid) and test condition (see 4.2).

d. Transfer time if other than specified in 4.2.1 or 4.2.2.

e. Measurements before and after cycling (see 4.3).

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MIL-STD-202-107

TABLE I. Thermal shock test conditions (air) 1/.

Test

condition

Number of

cycles

Test

condition

Number of

cycles

Test

condition

Number of

cycles

Step A 5 B 5 C 5

A-1 25 B-1 25 C-1 25

A-2 50 B-2 50 C-2 50

A-3 100 B-3 100 C-3 100

Temperature Time Temperature Time Temperature Time

°C

-55 +0, -3

25 +10, -5

85 +3, -0

25 +10, -5

See table II

5 minutes

maximum

°C

-65 +0, -5

25 +10, -5

125 +3, -0

25 +10, -5

See table II

5 minutes

maximum

°C

-65 +0, -5

25 +10, -5

200 +5, -0

25 +10, -5

See table II

5 minutes

maximum

Test

condition

Number of

cycles

Test

condition

Number of

cycles

Test

condition

Number of

cycles

Step D 5 E 5 F 5

D-1 25 E-1 25 F-1 25

D-2 50 E-2 50 F-2 50

D-3 100 E-3 100 F-3 100

Temperature Time Temperature Time Temperature Time

°C

-65 +0, -5

25 +10, -5

350 +5, -0

25 +10, -5

See table II

5 minutes

maximum

°C

-65 +0, -5

25 +10, -5

500 +5, -0

25 +10, -5

See table II

5 minutes

maximum

°C

-65 +0, -5

25 +10, -5

150 +3, -0

25 +10, -5

See table II

5 minutes

maximum

1/ When method 102, condition A, B or D has been specified use condition A.

When method 102, condition C has been specified use condition B

TABLE II. Exposure time in air at temperature extremes.

Weight of specimen

Minimum time

(for steps 1 and 3)

1 ounce (28 grams and below)

Above 1 ounce (28 grams) to .3 pound (136 grams), inclusive

Above .3 pounds (136 grams) to 3 pounds (1.36 kilograms), inclusive

Above 3 pounds (1.36 kilograms) to 30 pounds (13.6 kilograms), inclusive

Above 30 pounds (13.6 kilograms) to 300 pounds (136 kilograms), inclusive

Above 300 pounds (136 kilograms)

Hours

1/4 (or as specified)

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MIL-STD-202-107

TABLE III. Thermal shock conditions (liquid).

Test

condition

Number

of cycles

Test

condition

Number

of cycles

Test

condition

Number

of cycles

Test

condition

Number

of cycles

Step AA 5 BB 5 CC 5 DD 5

AA-1 15 BB-1 15 CC-1 15 DD-1 15

AA-2 25 BB-2 25 CC-2 25 DD-2 25

Temperature Time Temperature Time Temperature Time Temperature Time

°C

-0 +2, -10

100 +10, -2

See

table V

°C

-65 +0, -10

125 +10, -0

See

table V

°C

-65 +0, -10

150 +10, -0

See

table V

°C

-65 +0, -10

200 +10, -0

See

table V

TABLE IV. Suggested thermal fluids. 1/ 2/

Test

condition

AA, AA-1, AA-2

fluids

BB, BB-1, BB-2

Fluids

CC, CC-1, CC-2

fluids

DD, DD-1, DD-2

fluids

Step 1 FC40 4/ or

Water 3/

FC77 4/ FC77 4/ FC77 4/

D02

D02-TS 6/

D/80

D02

D02-TS 6/

D/80

D02

D02-TS 6/

D/80

D02

D02-TS 6/

D/80

Step 2 FC40 4/

Water 3/

FC70

FC40 4/

FC70

FC40 4/

FC70 4/

UCON-WS 5/

UCON-WS} 5/

D02

D02-TS 6/

D03

D02

D02-TS 6/

D03

D02

D02-TS 6/

D03

D05

LS/230 6/

LS/215

1/ See 4.2.2.

2/ Ethylene glycol shall not be used as a thermal shock test fluid.

3/ Tap water is indicated as an acceptable fluid for this temperature range. Its suitability chemically shall be

established prior to use. A mixture of water and alcohol may be used to prevent freezing at the low

temperature extreme. The water shall not be allowed to boil at the upper temperature extreme.

4/ FC77, FC70, FC40 are the registered trademark of 3M.

5/ UCON-WS process fluid is the registered trademark of Union Carbide Corporation.

6/ D02, D02-TS, D03, D05, D/80, LS/215 and LS/230 are the registered trademark of Ausimont (Division of

Montedison).

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