How to Check whether a Sound Level Meter is Class 1

The current requirements for sound level meters are set out in the BS EN 61672 (identical to the IEC) series of standards. The Specifications are given in Part 1, Part 2 sets out the requirements for Pattern Evaluation Tests (type approval) and Part 3 describes the procedures for Periodic Testing (laboratory calibration).

Mandatory Requirements

It is a mandatory requirement of BS EN 61672: 3 to state on a calibration certificate whether evidence is available, from an independent testing organisation responsible for pattern approvals, to demonstrate that the model of sound level meter successfully completed the applicable pattern-evaluation tests given in BS EN 61672:2.

Controlled Conditions

The procedures in BS EN 61672: 3 are acoustic and electrical tests carried out under controlled laboratory conditions (80 – 105 kPa, 20 – 26°C and 25 – 70% relative humidity). It cannot be assumed that because an individual instrument passes the periodic tests from BS EN 61672: 3 that that model of instrument satisfies all the requirements of BS EN 61672:1.

Complying with the Standards

BS EN 61672: 2 sets out the requirements for Pattern Approval to demonstrate that a particular model of sound level meter achieves the requirements set out in BS EN 61672: 1 for Class 1 and Class 2 sound level meters. BS EN 61672: 1 and BS EN 61672: 2 address the acoustic and electrical performance under a range of environmental and electromagnetic conditions. They also set out the information that must be supplied with the sound level meter in order for it to comply with the standard.

Providing Evidence

In order to determine whether a particular model of sound level meter has been fully evaluated as being Class 1 or Class 2 (in accordance with BS EN 61672) the primary question to ask suppliers is therefore “can you provide evidence, from an independent testing organisation responsible for pattern approvals, that this model of sound level meter successfully completed the (Class 1 or 2) pattern-valuation tests given in BS EN 61672:2”.

Factors to Consider

Factors to be considered when evaluating evidence received in response to this request include:-

  • Does it refer specifically to BS EN or IEC 61672: Part 1;
  • Does it state that the instrument was approved or not approved;
  • Does it demonstrate that the testing was carried out by an independent testing organisation responsible for pattern approvals;
  • Does it state that the instrument successfully completed the applicable pattern evaluation tests given in BS EN or IEC 61672: Part 2; and
  • Was the testing carried out for the exact instrument in the configuration that you will be using it (e.g. with third octaves or other options installed and with or without weather protection for the microphone).