Related Manuals for Cirrus CR:270 Series
Summary of Contents for Cirrus CR:270 Series
- Page 1 CR:270 Series User Manual Page 1 CR:270 Series Sound Level Meters User Manual This manual, the software to which it relates, the program code and drawings are all: © Copyright Cirrus Research plc 1989-2015...
- Page 2 The content of this manual, any illustrations, technical information and descriptions within this document were correct at the time of going to print. Cirrus Research plc reserves the right to make any changes necessary, without notice, in line with the policy of continuing product development and improvement.
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Page 3: Table Of Contents
CR:270 Series User Manual Page 3 Overview........................4 Recommended Accessories ..................... 4 Quick Start ........................5 First time use....................... 6 Fundamental Precautions....................6 CR:270 Controls ......................7 Weighting ........................7 Range .......................... 7 Response ........................8 Display ......................... 8 Max Hold ........................ -
Page 4: Overview
The CR:270 series have all the features necessary to make a wide variety of Industrial noise measurements, and they comply with the Standard IEC 804 (BS 60804) for Inte... -
Page 5: Quick Start
CR:270 Series User Manual Page 5 Quick Start Power On dB(A) Check Battery 50-100 Range Set Switches for Calibration Response Display Calibrate Instrument Max Hold Check Range Sound Level Average Select Sound Level Function Peak Level Peak(C) Reset Record Measurement... -
Page 6: First Time Use
Page 6 CR:270 Series User Manual First time use. The instrument should be inspected for any signs of damage. The two batteries type 6F22 (NEDA 1604 or PP3) should be fitted into the battery compartment. See section 8 for details of changing the batteries. -
Page 7: Cr:270 Controls
CR:270 Series User Manual Page 7 CR:270 Controls Weighting This is the lowest position slide switch, Marked OFF dB(C) dB(A). The CR:274 and CR:273 instruments feature dB(Lin) in the place of dB(C). The left hand position OFF disconnects all power from the instrument and empties the Leq store. -
Page 8: Response
Page 8 CR:270 Series User Manual In the right position, marked >80 the instrument measures levels in the range 80 to 140dB. Thus, the total measuring range is about 32 to 140dB(A) for an instrument fitted with the MK:202 Microphone Capsule, and 27 to 140dB(A) for an instrument fitted with the MK:224 Microphone Capsule. -
Page 9: Reset All
CR:270 Series User Manual Page 9 If Leq display mode is selected the Leq measurement is reset. If PEAK(C) display mode is selected the peak level is reset. If SPL display mode is selected the Max Hold is reset. Reset All This button, when pressed, simultaneously resets the Leq measurement, the PEAK(C) &... -
Page 10: Cr:273 & Cr:274 Additional Functions
Page 10 CR:270 Series User Manual CR:273 & CR:274 Additional Functions General Overview The CR:273 & CR:274 sound level meters makes use of virtually the same functions and controls as the CR:271 & CR:272. The only functional difference is that the CR:273 & CR:274 has an... -
Page 11: Turning Off Octave Filters
CR:270 Series User Manual Page 11 Turning off Octave filters To turn off the octave filters press on the OCTAVE FILTER button for 5 seconds. When the octave filters are turned off the red LED's in the upper most label will all be extinguished. -
Page 12: Summary
Page 12 CR:270 Series User Manual Note: Some models of the CR:27x have a low battery annunciator . This is to make the instrument more internationally compatible. Summary Function Annunciator Cause Possible Action Overload Amplifier overload Move UP one range... -
Page 13: Calibration
CR:270 Series User Manual Page 13 Calibration It is vital that the calibration of ANY sound level meter is checked before and after each measurement. If this is done, it is reasonable to assume that the calibration during the measurement was correct. If this is NOT done, you will not subsequently be able to be certain that the instrument calibration was correct and you can never be certain the sound level was as measured. - Page 14 If this cannot be achieved the microphone or instrument may be at fault and a check should be made with Cirrus Research. As 'A' and 'C' weightings all have nominal zero correction loss at 1kHz, the reading on these two positions should be nominally the same.
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Page 15: Replacing The Batteries
Types of batteries The CR:270 series should be used with high quality batteries. These should be either Alkaline or Zinc Chloride type. Alkaline batteries will give a longer life than the lower cost Zinc Chloride batteries. -
Page 16: Selection Of Hearing Protection
Page 16 CR:270 Series User Manual Selection of Hearing Protection Prescription of hearing defenders, either ear plugs, muffs or defenders may be an important part of a noise measurement and control programme. Because of the wide range of hearing defenders that are available, as well as the different methods of determining suitable units, this is often a complex and time consuming process. -
Page 17: Example Of The Octave Band Method
CR:270 Series User Manual Page 17 Example of the Octave Band Method The noise levels measured from a machine are: (or L in dB(A)) measured over one (or more) complete cycle: 103.2 dB(A) Octave Band Centre 1000 2000 4000 8000... -
Page 18: Example Of The Hml Method
Page 18 CR:270 Series User Manual Therefore, in this example, the ear protection reduces the noise level from 103.2 dB(A) to 82 dB(A). Example of the HML Method The noise levels measured from a machine are: or L (A weighted Leq) 103.2 dB(A) -
Page 19: Rating Plate Information
CR:270 Series User Manual Page 19 Rating Plate Information The CR:27x meets IEC 651 (BS EN 60651) and IEC804 (BS EN 60804) Types 1 or 2, depending on the microphone fitted. The specifications IEC 651 and IEC 804 require that this manual provides detailed information to verify that the specifications are met. - Page 20 Page 20 CR:270 Series User Manual Peak is fitted IEC 804 11.2.9 & IEC 651 11.2.7 The effect of vibrations is such that 5g in any direction will not cause a reading on scale. IEC 804 11.2.10 & IEC 651 11.2.8 The unit is unaffected by a field of 80 A/m IEC 804 11.2.11 &...
- Page 21 CR:270 Series User Manual Page 21 IEC 804 11.2.20 & IEC 651 11.2.21 The warm up period is 4 minutes although it is normally ready within 60 secs. IEC 804 11.2.21 The settling time before valid Leq readings are obtained is one minute.
- Page 22 Page 22 CR:270 Series User Manual IEC 1260 7c Not applicable IEC 1260 7d The nominal midband frequencies for the filters are known as 31.5Hz ,63Hz, 125Hz, 250Hz, 500Hz, 1000Hz, 2000Hz, 4000Hz, 8000Hz, 16000Hz. IEC 1260 7e The filters are derived from the 'Base-two' formula. Exact centre frequencies are 31,25Hz, 62.50Hz, 125.00Hz, 250.00Hz, 500.00Hz, 1000.0Hz, 2000,0Hz, 4000.0Hz,...
- Page 23 CR:270 Series User Manual Page 23 IEC 1260 7s The permanent presence of LCD display battery annunciator indicates that the batteries are not sufficient to run the instrument correctly. IEC 1260 7t The filter is integral to the CR:273 and CR:274 IEC 1260 7u The instrument is fully functional 10 seconds after switch on.
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Page 24: Specification
Page 24 CR:270 Series User Manual Specification The range of measurement for Leq and SPL measurement with a standard assembly is:- CR:272 & CR:274 32 to 140 dB(A) 50 to 140 dB(C) CR:271 & CR:273 27 to 140dB(A) 47 to 140dB(C) The range of measurement for Peak measurement with a standard assembly is:- CR:272 &... -
Page 25: Ce Certificate Of Conformity
CR:270 Series User Manual Page 25 CE Certificate of Conformity Cirrus Research plc Hunmanby UK CE Certificate of Conformity Manufacturer: Cirrus Research plc Acoustic House, Bridlington Road Hunmanby, North Yorkshire, YO14 0PH United Kingdom Telephone +44 1723 891655 Equipment Description... -
Page 26: Warranty Information
14. In the event of any dispute on the terms of the warranty Cirrus Research plc will accept pendulum arbitration by the United Kingdom Institute of Acoustics Ltd. -
Page 27: Cirrus Research Offices
Page 27 Cirrus Research Offices The addresses given below are the Cirrus Research plc offices. Cirrus Research plc also have approved distributors and agents is many countries worldwide. For details of your local representative, please contact Cirrus Research plc at the address below. Contact details for Cirrus Research authorised distributors and agents are also available from the Internet Web site at the address shown below.
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