MIL-STD-202H.pdf - 第66页

MI L - S TD - 202 -1 10 CO NT E N T S PARAGRAPH PAG E FOREW ORD … ………………………………………………………. ii 1. SCOPE 1 1.1 Purpose …… ………………… …………………. …… .. …………. 1 2. APPLICABLE D O C U M EN T S 1 3. DEFINTIONS 1 4. GENERAL RE Q UI R E…

MIL-STD-202-110

FOREWORD

1. This standard is approved for use by all Departments and Agencies of the Department of Defense.

2. This entire standard has been revised. This revision has resulted in many changes to the format, but the most

significant one is the splitting the document into test methods. See MIL-STD-202 for the change summary.

3. Comments, suggestions, or questions on this document should be emailed to std202@dla.mil or addressed to:

Commander, Defense Logistics Agency, DLA Land and Maritime, ATTN: VAT, P.O. Box 3990, Columbus, OH

43218–3990. Since contact information can change, you may want to verify the currency of this address

information using the ASSIST Online database at https://assist.dla.mil.

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MIL-STD-202-110

CONTENTS

PARAGRAPH PAGE

FOREWORD…………………………………………………………. ii

1. SCOPE 1

1.1 Purpose………………………………………….……..…………. 1

2. APPLICABLE DOCUMENTS 1

3. DEFINTIONS 1

4. GENERAL REQUIREMENTS 1

4.1 Apparatus ……………………………………………..…………. 1

4.1.1 Test facility……………………………………………………….. 1

4.1.1.1 Dust requirements.. …………………………………………….. 1

4.2. Procedure……..………………..….…………….………………. 2

5. DETAILED REQUIREMENTS 2

5.1 Summary……………..…………………………..………………. 2

6. NOTES 3

6.1 Supersession data………………………………………………. 3

iii

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MIL-STD-202-110

METHOD 110

SAND AND DUST

1. SCOPE

1.1 Purpose. The dust test is used during the development, test, and evaluation of equipment to ascertain their

ability to resist the effects of a dry dust (fine sand) laden atmosphere. This test simulates the effect of sharp edged

dust (fine sand) particles, up to 150 microns in size, which may penetrate into cracks, crevices, bearings, and joints,

and cause a variety of damage such as fouling moving parts, making relays inoperative, forming electrically

conductive bridges with resulting "shorts" and acting as a nucleus for the collection of water vapor, and hence a

source of possible corrosion and malfunction of equipment. This test is applicable to all mechanical, electrical,

electronic, electrochemical, and electromechanical devices for which exposure to the effects of a dry dust (fine sand)

laden atmosphere is anticipated.

2. APPLICABLE DOCUMENTS

This section not applicable to this standard.

3. DEFINTIONS

This section not applicable to this standard.

4. GENERAL REQUIREMENTS

4.1. Apparatus.

4.1.1 Test facility. The test facility shall consist of a chamber and accessories to control dust concentration,

velocity, temperature, and humidity of dust-laden air. In order to provide adequate circulation of the dust laden air, no

more than 50 percent of the cross-sectional area (normal to air flow) and 30 percent of the volume of the chamber

shall be occupied by the test item(s). The chamber shall be provided with a suitable means of maintaining and

verifying the dust concentration in circulation. A minimum acceptable means for doing this is by use of a properly

calibrated smoke meter and standard light source. The dust-laden air shall be introduced into the test space in such

a manner as to allow it to become approximately laminar in flow before it strikes the test item.

4.1.1.1 Dust requirements. The dust used in this test shall be a fine sand (97-99% by weight SiO

) of angular

structure, and shall have the following size distribution as determined by weight, using the

U.S. Standard Sieve Series.

a. 100 percent of this dust shall pass through a 100-mesh screen.

b. 98 ±2 percent of the dust shall pass through a 140-mesh screen.

c. 90 ±2 percent of the dust shall pass through a 200-mesh screen.

d. 75 ±2 percent of the dust shall pass through a 325-mesh screen.

"140-mesh silica flour" as produced by the Ottawa Silica Company, Ottawa, Illinois, or equal, is satisfactory for use in

the performance of these tests.

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