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CASELLA USA 

 

 

 

CEL-240 DIGITAL SOUND LEVEL METER 
FREQUENTLY ASKED QUESTIONS

 

 

Casella USA 

Page 3 of 6 

(800) 366-2966 

31 Jan 2008 

[email protected]

 

 

FAQ’s:  COMPARISON OF MODELS 

 

What models are there in the range? 

A single model variant is available – the 

CEL-240

. It is a completely new design compared to the 

earlier CEL-231 & 254 models in the original 200 series. 

 
What are the main features & benefits of the CEL-240? 

The main differences between the CEL-240 and the earlier 231/254 instruments are the use of digital 
signal processing (DSP) technology and a low power consumption microprocessor that is unique in 
such  a  low  cost  instrument.  The  meter  features  the  instantaneous  sound  level  plus  the  maximum 
hold  feature  on  all  screens  plus  a  real  time  bar  graph  display.  This  makes  the 

CEL-240

  model 

extremely useful in circumstances where the noise levels are fluctuating and where the time history 
trending graph will be useful for seeing changing noise levels of short events. A simple digital output 
is also available to link to a personal computer for basic data logging applications. 
 

 

FAQ’s:  OPERATION 

 
 
How long will standard alkaline batteries last in a CEL-240? 

A set of 3 x AA alkaline cells can power a 

CEL-240

 for more than 

35 hour’s

 continuous operation at 

normal room temperature.  Lower temperatures will reduce useful battery life.  Good quality alkaline 
batteries are recommended for longest running time. 
 

Can rechargeable batteries be used in a CEL-240? 

A set of 3 x AA NiMH rechargeable batteries can be used instead of alkaline batteries and battery life 
will be around the same time at normal room temperature.  The rechargeable batteries will operate 
successfully  down  to  lower  temperatures  than  an  alkaline  battery  set.  NiMH  batteries  must  be 
recharged  outside  the 

CEL-240

  and  can  be  used  repeatedly  in  these  instruments.  When  NiMH 

batteries  are  run  down  they  can  be  recharged  in  a  few  hours  and  used  again  up  to  the  number of 
recharge cycles recommended by the battery manufacturer. Typically this will be around 300 – 500 
charge cycles. 
 

How can the instrument be powered from an external source? 

The 

CEL-240

  is  designed  to  be  powered  from  an  external  supply  via  the  USB  connector  that  is 

available on the bottom of the meter. This takes the usual 5Vdc supply from the USB port of a laptop 
or desktop computer via a suitable cable. 

 
Can the microphone of a CEL-240 be removed? 

The  microphone  unit  of  a 

CEL-240

  is  not  removable  therefore  remote  operation  is  not  normally 

possible.  In  special  circumstances  it  may  be  possible  to  fit  a  length  of  plastic  tubing  of  ¼”  internal 
diameter  over  the  end  of  the  microphone  in  order  to  place  the  open  end  near  to  a  machine  noise 
source that would be dangerous to approach so closely. 
 

Can the CEL-240 be used for outdoor measurements? 

The 

CEL-240

 is not designed for extended use outdoors since it is not completely sealed against the 

likely wind and rain that would spoil such measurements. 

Summary of Contents for CEL 240 Series

Page 1: ...trument be powered from an external source Can the microphone of a CEL 240 be removed Can the CEL 240 be used for outdoor measurements How quickly does the digital display update during measurements Is the time history trace stored in the CEL 240 What outputs are available from the CEL 240 What are the characteristics of the ac output What are the characteristics of the dc signal What are the char...

Page 2: ...vice versa Both models feature ANSI type 2 accuracy for overall measurements The new CEL 350 dBadge dosimeter adds a small badge style dosimeter with cable less microphone to the range for added convenience CEL 400 Series The mid range sound level meters are the CEL 430 450 and 490 providing recording of level against time or level against frequency The 450 and 490 instruments are fitted with para...

Page 3: ...s are recommended for longest running time Can rechargeable batteries be used in a CEL 240 A set of 3 x AA NiMH rechargeable batteries can be used instead of alkaline batteries and battery life will be around the same time at normal room temperature The rechargeable batteries will operate successfully down to lower temperatures than an alkaline battery set NiMH batteries must be recharged outside ...

Page 4: ... The C setting is recommended for making audio recordings since it has a better wider and flatter frequency response than the A weighting The ac signal is available on the 2 5 mm jack socket at a level of up to 0 85 V rms for full scale deflection This means that for a sound level of 100 dB measured on the Lo range of the meter the output would be 0 85 V rms A signal at half the range FSD would ou...

Page 5: ...er to see what is happening Use the Fast response to more accurately follow the changing noise levels as they rise and fall Use the Impulse response only when the regulations require it What exchange rates or Q values are available in the CEL 240 There is no specific exchange rate available in the meters since this function is only associated with instruments that can measure the time average nois...

Page 6: ... with a personal computer running the optional dB24 software FAQ s APPLICATIONS What markets is the instrument designed for There are three main markets for the CEL 240 a simple meter for monitoring noise exposure in the workplace a general purpose sound level meter for many environmental nuisance sources a short term noise meter for quick measurements on specific noise sources How are these marke...

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