How many helmets do I need to test from a lot of 100?

For visual and dimensional checks, you need to sample 13 helmets. For performance tests, you need to sample 3 helmets. (Table 1 & Table 2)

What happens if one helmet fails a performance test?

The entire lot is considered to not conform to the requirements, as the acceptance number for performance tests is zero. (Clause 4.2.1)

If I have a lot of 200 helmets, how many can fail the visual inspection?

For a lot size of 151-300, the sample size is 20 and the acceptance number is 1. Therefore, if more than one helmet in the sample is defective, the lot is rejected. (Table 1)

IS 9695

: 1980

Code of practice for provision and maintenance of water supplies and firefighting

CurrentSpecializedTesting MethodFire Safety · Fire Fighting

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This code of practice provides guidelines for the provision and maintenance of water supplies for firefighting purposes. It covers sources of water, pumping arrangements, water storage requirements, and the layout and maintenance of water mains and hydrants. The standard aims to ensure a reliable and adequate water supply is available for combating fires in various premises.

Code of practice for provision and maintenance of water supplies and firefighting

Quick Reference Values

Sample size for lot size 51-150 (Visual Insp.)13

Acceptance number for lot size 51-150 (Visual Insp.)1

Sample size for lot size 51-150 (Performance Test)3

Acceptance number for lot size 51-150 (Performance Test)0

Sample size for lot size 301-500 (Visual Insp.)32

Acceptance number for lot size 301-500 (Visual Insp.)2

Sample size for lot size 301-500 (Performance Test)5

Acceptance number for lot size 301-500 (Performance Test)0

Practical Notes

This is a procedural standard for quality control and must be used in conjunction with the relevant performance specification standard for the specific type of helmet (e.g., IS 2925 for industrial helmets).

Note the two separate sampling plans: a larger sample size for non-destructive visual and dimensional checks (Table 1) and a smaller size for destructive performance tests (Table 2).

The acceptance number for all performance tests is zero, indicating that no failure is permitted in any of the helmets sampled for these tests.