Extech Extech 407355 Manual

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Melrose, MA 02176

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Toll Free 1-800-517-8431

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User's Guide

Noise Dosimeter with PC Interface

Model 407355

Introduction

Congratulations on your purchase of the Extech 407355 Personal Noise Dosimeter. The
407355 is designed to test noise exposure in accordance with OSHA, MSHA, DOD,
ACGIH, and ISO standards. Fast and easy on-site surveys help determine noise
reduction requirements. The meter can also be used in SLM (sound level meter) mode
where sound pressure levels are monitored from 70 to 140dB.

The built-in RS-232 PC interface offers the following capabilities:

 In SOUND LEVEL METER (SLM) MODE: The meter can be connected to PC while

taking measurements so that readings can be stored in a file and readings can be
viewed in a variety of display configurations (graph, list, etc.).

 In DOSIMETER mode: The meter can perform a noise survey after which the user

can transfer the survey data to a PC.

Careful use of this device will provide years of reliable service.

Test Equipment Depot - 800.517.8431 - 99 Washington Street Melrose, MA 02176

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Specifications

Display Multi-function LCD
Units of measure dBA (‘A’ weighted decibels) for sound level

% DOSE for accumulated noise exposure

Measurement ranges 70 to 140dBA for sound level (SPL) measurements

0.01 to 99.99 %DOSE for noise exposure surveys
Standards applied ANSI S1.25-1991 A-weighting
ISO-1999
BS 6402: 1983
Criterion level 80, 84, 85, and 90dB (selectable)
Threshold level 70 to 90dB in 1dB steps (selectable)
Exchange rate 3, 4, 5, and 6dB (selectable)
High level detector appears on LCD when measurement exceeds 115dBA
Peak flag PK appears on LCD when measurement exceeds 140dBA
Accuracy ±1.5dB
Frequency weighting ‘A’ weighting
Frequency response 31.5Hz to 8 kHz
Response time F (FAST) and S (SLOW) selectable
Operating Temperature 32 to 122
Operating Humidity 10 to 90% RH
Storage Temperature 14 to 140
Storage Humidity 10 to 75% RH
Battery power Four (4) 1.5V ‘AAA’ batteries
Battery life 40 hours (approx.)
Dimensions 4.2 (L) x 2.4 (W) x 1.3 (H)"

106 (L) x 60 (W) x 34 (H) mm

Weight Approx. 12.3 oz. (350g) with batteries

o

F (0 to 50oC)

o

F (-10 to 60oC)

Descriptions

Display Description

1. FAST Response Time mode

2. SLOW Response Time mode

3. Noise Exposure test active

4. Memory mode alert

5. Noise Exposure test paused

6. Unit of measure for Noise
Exposure test

7. Battery Status Indicator

8. Event memory banks (E1-E5)

9. 115dB limit (headphone) indicator

10. Numerical display digits

11. Unit of measure for sound level readings

12. 140dB PEAK indicator

13. Elapsed time mode for noise exposure tests

1 2 3 4 5 6

7

MEM

E5

8 9 10 11

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Meter Description

1. Microphone (lapel clip not shown)

2. Microphone cable

3. Microphone connector

4. LCD display

5. Push-buttons:
ON-OFF Press to turn the meter ON; Press and hold to turn

the meter OFF.

RESET This button has a variety of uses including clearing stored

data and accessing the Programming mode as described in the
manual.

RUN Press to begin a noise survey test. Also used

as the Left Arrow in the Programming mode

CLOCK Press to view the Date and Time. Also

used as the Right Arrow in Programming mode

MODE Press to select ELAPSED TIMER, SLM

(dBA) mode, or noise survey (%DOSE) mode. Also
used as the Down Arrow in the Programming mode

EVENT Press to select a memory bank (E1

through E5). Also used as the Up Arrow in the
Programming mode

6. RS-232 PC Interface plug

7. RS-232 PC Interface jack

8. Calibration potentiometer

9. Battery compartment screw

10. Belt clip / Battery compartment cover

11. Battery compartment

12. Microphone jack

13. Housing screws (service personnel only)

1
2

3

4

5

6

12

7 8

9

13

10

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Model 407355 Version 2.1 September 2004

Operation

Getting Started

1. Power the instrument by pressing the green button.

2. When the unit is turned on, all display annunciators switch on briefly followed by
‘dOSE’, the Criterion Level (Lc), Threshold Level (Lt), and Exchange Rate (ER)
respectively. These parameters are defined in the Noise Exposure related sections of
this manual.

3. If the meter does not switch on when the power button is pressed, check that the
batteries are installed and are fresh. Refer to the Battery Replacement section of this
manual.

4. To turn the meter OFF, press and hold the green power button; the display will count
down from 3dB to 0dB and then switch off.

5. The 407355 can be used as a Sound Level Meter or a Dosimeter.

Sound Level Meter Operation (dBA)

Press the MODE button repeatedly until the unit of measure is dBA (A-weighted decibels).
In SLM mode the meter operates as a Type 2 sound level meter. The 407355 measures
and displays sound pressure levels from 70 to 140dB. Read the measured sound level on
the LCD. For Sound Level measurements < 68dBA the LCD will display dashed lines. For
readings > 115dBA, the headphone icon appears. For readings > 140dBA, the Peak
Detector PK icon appears.

Dosimeter Operation (Accumulated Noise Exposure - %DOSE)

1. Program the Response Time (Fast or Slow), Criterion Level (Lc), Exchange Rate (ER),
and Threshold Level (Lt) manually (see Programming section) or through the supplied
software (see PC Interface section).

2. Use the MODE button to select %DOSE as the unit of measure.

3. Select an unused Event Bank (E1 through E5) using the EVENT button.

4. Attach the meter to the user’s belt buckle, breast pocket, or where convenient

5. Clip the microphone as close as possible to the user’s ear (shirt collar, for example)
using the lapel clip.

6. Route the cable as to not hinder the working movements of the user.

7. Press the RUN button to begin measuring accumulated noise exposure. The Clock
display icon will switch on.

8. Press the RUN button momentarily to PAUSE the test (PAUSE display icon will switch
on). Press the RUN button again to resume the test (PAUSE icon will switch off).

9. Use the MODE button at any time to view the elapsed time of the test. Press the
MODE button until the TIME display icon appears. Now the elapsed time will appear in
hours and minutes. Press the RUN button again to return to the %DOSE display.

10. To end the noise survey, press and hold the RUN key for 3 seconds. Read the
accumulated noise exposure value on the LCD.

11. Testing notes:

 Never shout into the microphone as this will affect the test.
 To obtain reliable data, the user’s activities must reflect a typical working day.
 For best results, test over the course of several days and average the %DOSE

Refer to the dosimetry parameter descriptions below:

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Model 407355 Version 2.1 September 2004

Test Equipment Depot - 800.517.8431 - 99 Washington Street Melrose, MA 02176

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Event Select

Press the EVENT button to enter the EVENT mode. Each time the EVENT button is
pressed the LCD increments the Event bank (E1 through E5). Each bank is a memory
location. The user can store (or write over) the data in any of these locations. Each bank
location (E1, for example) is displayed on the LCD along with the stored data. If data is
present in a bank, the bank ID blinks. To erase data in a bank, press and hold the RESET
button until the display ID stops blinking.

% DOSE

The unit of measure, % DOSE, is used to quantify noise exposure measured during a
work shift. 100% dose is the maximum allowable noise exposure in accordance with
OSHA, MSHA, DOD, ACGIH, and ISO standards. Most standards specify Criterion
Level, Exchange Rate, Response Time, and Frequency weighting for the dosimeter as
discussed next.

CRITERION LEVEL (Lc)

To take an on-site noise exposure survey in accordance with standards such as OSHA
and MSHA, the dosimeter’s Criterion Level must first be set. The 100% DOSE
parameter discussed above is determined by the following equation: 100% DOSE =
Criterion Level for 8 hours. Each country has a unique Criterion Level (most countries,
including the U.S., use 90dB). The Criterion level is selectable (80, 84, 85, or 90dB).
Select the appropriate level per the Programming section of this manual.

EXCHANGE RATE (ER)

Exchange rate is best illustrated by example; refer to the following example: Since
100% DOSE = Criterion Level for 8 hours, a person would receive 50% DOSE in 4
hours if the noise level equals the Criterion Level setting. Now consider a Criterion
Level of 90dB, a noise measurement of 95dB (5dBA higher than the Criterion Level),
and an Exchange Rate of 5dB; in this example a 100% DOSE would be received in
only 4 hours. This is because with a 5dB Exchange Rate, a 5dB increase in sound level
is considered a doubling of the DOSE. Other Exchange Rates can be selected (3, 4, 5,
or 6dB). Refer to the local regulations or standards.

FAST (F) SLOW (S) RESPONSE TIME

Set the response time to Fast (F) to capture quick bursts of sound such as discharging
firearms, fireworks, hammering, and other impulse noises. Use the Slow (S) setting if
the noise under test is more of a continuous drone or background din. The Slow setting
is typically specified by OSHA and MSHA standards for use in noise surveys. Refer to
the Programming section of this manual to set the response time.

THRESHOLD LEVEL (Lt)

The threshold level is the sound level at which the 407354 begins to integrate noise into
the exposure test. For example, if the threshold level (Lt) is set to 85dB, the meter will
integrate all noise that equals or exceeds 85 dB. Sound levels below this threshold
would not be included in the dose calculation. See the Programming section to change
the level. The Threshold Level can be set from 70 to 90dB in 1 dB steps.

PEAK FLAG

When sound levels above 140dB are present the meter displays the PK symbol

HIGH LEVEL INDICATOR

When sound levels above 115dB are present the meter displays the headphone
symbol

Real Time Clock

Press the CLOCK key to display the current Day and Time accompanied by the TIME icon
blinking. Note that the DATE and TIME settings are saved when the meter is turned off. To
set the TIME and DATE refer to the Programming section.

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Model 407355 Version 2.1 September 2004