Casella USA CEL 240 Series User manual

Casella USA
17 Old Nashua Rd #15
Amherst, NH 03031 USA
TF [phone]
[email protected]
CEL-240 Digital Sound Level Meter
Operator Manual
HB-3331-01

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CEL-240 Instruction Manual. HB3331-01 ENGLISH
Digital Sound LevelMeter
December 07
Introduction
Congratulations on your purchase of the CEL-240 Digital Sound Level Meter. The CEL-
240 has been designed to perform accurate noise measurements through a wide decibel
range. The CEL-240 is a completely digital sound level meter, designed for stable,
reliable performance, fully compliant with international sound level meter standards.
This instruction manual is to help you get the most benefit from your CEL-240 and to
ensure accurate noise measurements.
Diagrams
The illustrations and diagrams of the CEL-240 instrument and display screens are located
at the beginning of this manual and are referenced in the operation of the instrument
below. Please refer to the appropriate diagram at the beginning of this manual.
Figure A: CEL-240 Figure B: Battery Compartment
1. Microphone 1. Battery direction
2. Power button 2. ¼” Tripod socket
3. Display Figure C: Connections
4. Left key 1. USB Socket
5. Right key 2. Auxiliary socket (2.5mm Stereo)
Figure D: Display Figure E: Calibration screen
1. Battery indicator Figure F: Completed calibration
2. Over range indicator Figure G: Contrast adjustment screen
3. decibel level Figure H: Calibration level setting
4. Analogue display bar Figure I: Source input selection
5. Measurement scale Figure J: Time history display

6. Maximum decibel level Figure K: Power off screen
7. Instrument settings
8. Reset
Preparation for Use
Install three AA Alkaline (or NiMH) batteries observing polarity (Figure B).
Always replace batteries when the battery indicator (Figure D.1) shows the batteries are
low to prevent the CEL-240 switching off during monitoring.
The CEL-240 is now ready for operation.
General Operation
1. Switch on bypressing the power button (Figure A.2). The instrumentdisplays the
firmware version (e.g. v1.01) and serial number (e.g. 0108121) followed by the
main measurement screen (Figure D).
2. Calibrate the instrument as required. See ‘Calibration’section.
3. Place the windshield over the microphone prior to any measurement.
4. The CEL-240 will display a bargraph (Figure D) or time history (Figure J)
display. See ‘Instrument Settings’ to change time and frequency weightings, or
type of display.
5. Instantaneous and maximum sound pressure levels are displayed on the
measurement screen with the relevant time and frequency weighting. The
maximum sound pressure level can be reset bypressingthe right key at any
time.
6. Once measurements are complete, switch off the instrument by holding down the
power key(Figure A.2). The power key needs to be held down for 3 seconds to
prevent accidental switch off.
Calibration
It is recommended that an acoustic calibration is performed using a CEL-110/2 or CEL-
110/1 calibrator before and after measurements as follows:- Switch on the acoustic
calibrator (refer to calibrator instruction manual). If the calibrator has 114dB output,
ensure the CEL-240 is set to the 60-130dB range. Place calibrator firmly over the
microphone.
The CEL-240 automatically detects a 1KHz tone from a 94 or 114dB calibrator and
enters calibration mode (Figure E). Press left key to perform a calibration or right
key to exit. Upon successful calibration, the screen will be as in Figure F.
Instrument Settings

When on the measurement screen, settings can be changed using the left key (settings
button) (Figure D.7). Once pressed, an arrow will appear next to the settings
button to show you are in the settings menu. Consecutively pressing the
left button will cycle through setting screens. Pressing the right key will make changes to
the current selection. Current settings are saved when switched off.
1. Time weightings (Fast, Slow or Impulse)
2. Measurement range (30-100dB or 60-130dB)
3. Frequency weightings (Aor C)
4. Display type, either bargraph or time history graph (1 or 5 minute time base)
Time weightings: Use Fast response for comparatively stable noise, or select Slow
response for slowly varying noise. Impulse response may be
selected for more rapidly varying and impulsive noise.
Measurement range: Care should be taken to select the correct measurement range
depending on the noise climate being measured. Ensure the noise
being measured is within the measurement range such that the over
range indicator is not displayed (Figure D.2). Noise levels
below the measurement range are displayed as ‘--.-dB’
Frequency weightings:Frequency weightings are used to represent the human ears
response to noise. The ‘A’ weighting is typically used for general
noise measurements. ‘C’ weighting is used at very high noise
levels.
Display type: The main display can be changed between abargraph (Figure D) to
a time history display (Figure J). The time history shows how the
maximum sound pressure has varied through either a 1 minute or 5
minute time base. Press the right key to select the bargraph
, 1minute , or 5 minute time history . Press
the left key to confirm the changes and return to the
measurement screen.
Configuration Menu
The configuration menu is used to make changes to three specific settings:
•Display contrast
•Calibration level
•Signal input source
To enter the configuration menu, hold down the right key when the CEL-240 is switched
off and press the ‘power’ key. The ‘Contrast’ screen is then displayed (Figure G). Press
the right key to adjust the contrast as appropriate and then press the left key
to accept the changes.

The calibration level screen will then be displayed (Figure H). This screen is used to set
the exact reference level used by the acoustic calibrator. Refer to the calibration
certificate for the acoustic calibrator for the calibrator output level.
The ‘Signal input source’ screen (Figure I) will then be shown. NOTE: this option is for
the use of acoustic laboratories only. This allows the signal input to be routed from either
the inbuilt microphone or from an external signal generator connected via the auxiliary
2.5mm headphone socket. Press the right key to switch between microphone
input or Alternating Current input . The default power up selection
is for microphone input. Press the left key to confirm any changes.
Specification
General
Designed to provide functionality with respect to the following international standards:
IEC 61672-1 2002-5 (Electro-Acoustics – Sound Level Meters) Group ‘X’
instruments, Performance Class 2.
ANSI S1.4 Type 2A Specification for Sound Level Meters
Range: Display range: 30-130dB(A) RMS, available in 2 ranges, 30-100dB and
60-130dB. Linear operating range 10dB above noise floor.
RMS Frequency Weightings
A and C filter weightings, satisfying IEC 61672-1: 2002 Class 2, ANSI S1.4 Type 2A.
Noise Floor
Total noise floor typically <33dB(A).
Frequency Response
Overall frequency response as per IEC 61672-1: (2002) Class 2, ANSI S1.4 Type 2A.
Time Weightings
Fast, Slow and Impulsive according to IEC 61672-1: (2002), ANSI S1.4 Type 2A.
Reference Conditions
20oC air temperature, 65% Relative Humidity, 101.325kPa atmospheric pressure.
Nominal reference level = 114.0dB at 1kHz. Free field perpendicular incidence.
Operating Environmental Conditions
Humidity: 5 to 90%RH in the absence of condensation.
Temperature range: 0 to 40oC.
Pressure: 65 to 108kPa

Effects of Humidity: Less than ±0.5dBover the range 30to 90% relative
humidity (non-condensing), relative to the value at
reference conditions.
Storage EnvironmentalConditions
Humidity: 0 to 90%RH in the absence of condensation.
Temperature range: -20 to +60oC.
Pressure: 65 to 108kPa
Microphone
Internal electret capsule 10mV/Pa nom +/-3dB within ½” preamplifier.
Calibration
Auto calibration by application of 1kHz @ 114or 94dB calibrator (CEL-110/2 or CEL-
110/1). ±1dBcalibration range.
PowerSupply
External DC: 5VDC (via USB 5 pin mini B)
Batteries: 3x AA, Rechargeable NiMH or Alkaline cells
Battery Life: Typically 35hours
Power consumption: ~65mA
Electromagnetic Compatibility
Instrumentation is designed and tested to comply with the following EMC and ESD
Standards:-
IEC 61000-4-2 Testing and Measuring Techniques - Electrostatic discharge
immunity tests.
IEC 61000-4-3 Electromagnetic compatibility(EMC) - Radiated electromagnetic
field tests.
IEC 61000-4-6 Electromagnetic compatibility (EMC) - Immunity to conducted
disturbances induced byradio frequencyfields. Tested at 10V/m or
greater.
Effects of AC PowerFrequency Fields
Less than ±0.5dB change in 74dB(A) 925Hz reference level when subjected to 160A/m
AC magnetic field at 50and 60Hz.
Display
128x128 Mono Graphics LCD, 0.5 secondsupdaterate.
Connectivity
USB: USB 2.0 via ‘mini B’ socket. For SPL output (software required) weighted as per
selected frequency and time weightings.
AUX Socket (2.5mm stereo):

AC output provided for DAT tape / PC wav file recording or headphone
applications. Approx 0.5V RMS Full Scale Deflection (FSD) ‘A’ weighted output
on selected range. Minimum load impedance 22kΩ. (Optional DC Output via
internal configuration, 0 to 3.3V DC for FSD on selected range. Output
corresponds to selected weighting, 2kΩOutput impedance).
AC input used for electrical calibration, switched on via configuration menu.
Service and Warranty
The manufacturer undertakes to rectify any defect in the instrument directly attributable
to faulty design or assembly and which becomes apparent during the warranty period. In
order to take advantage of this warranty, the instrument must be returned, carriage paid,
to the manufacturer’s factory or accredited agent, where necessary repairs will be carried
out.
The warranty period runs for 24 months from the date of receipt of goods, with
exceptions on certain specialised components supplied by other manufacturers that may
be warranted for shorter or longer periods by their actual manufacturers. In all such cases,
the benefit of these undertakings will be passed on to the user. CASELLA CEL’s liability
is limited to items of their own manufacture, and they do not accept liability for any loss
resulting from the operation or interpretation of the results from this equipment. To
obtain repair under warranty, the instrument should be packed and returned in it’s
original packing or an equivalent either to CASELLA CEL’s local agent, or in the case of
U.K. domestic sales, to the CASELLA CEL Service Department at Bedford., UK. Please
include the following information:
Instrument Type(s), Serial Number(s) and Firmware Version Number(s), Customer name
and address, Contact name and phone number, details of any PC and Software involved,
including Version Number(s), reason for returning the equipment with a detailed
description of the fault and a list of any error messages that may have been displayed.
For calibration, service or technical support enquires please contact:
E-mail: [e-mail]
Telephone: [phone]
CASELLA CEL
Regent House,
Wolseley Road,
Kempston,
Bedford,
MK42 7JY, U.K.
Phone: [phone]

Fax: [phone]
E-mail: [e-mail]
Web: www.casellacel.com
CASELLA USA
17Old Nashua Road,
# 15, Amherst,
NH 03031,
U.S.A.
Toll Free: [phone]
Fax: [phone]
E-mail: [e-mail]
Web: www.casellaUSA.com
CASELLA ESPANAS.A.
Polígono Európolis
Calle C, nº4B
28230 Las Rozas - Madrid
Spain
Phone: + 34 91 640 75 19
Fax: + 34 91 636 01 96
E-mail: [e-mail]
Web: www.casella-es.com