ST-21D

Integrating Algorithms for Occupational Noise

ST-21D Sound Level Meters fully comply with the latest Class 2 IEC 61672:2013 standard. Advanced integrating algorithms designed to withstand industrial conditions.

Equates continuous sound level and sound exposure after choosing a time period, an ideal tool for occupational noise measurements, such as those required by the Controls of Noise at Work Regulations or OSHA Occupational Noise standards. At the front line, ensure the protection of hearing and occupational safety for employees.

Class 2 Sound Level Meter

Designed for Environmental & Occupational Noise Measurements
High Precision
IEC 61672:2013 Class 2 Standard
±0.7 dB High Accuracy
Smart Integration
Measures and Displays Leq Value
Adjustable A/C/Z Frequency Weightings
Built-In Datalogger
Download raw data directly on your computer via USB cable

Integrating Algorithms for
Occupational Noise

ST-21D Sound Level Meters fully comply with IEC 61672:2013 standard. The meter measures and displays the equivalent continuous sound level and sound exposure within the selected time period, ideal for occupational noise measurements.

Integrating Algorithms for
Occupational Noise

ST-21D Sound Level Meters fully comply with IEC 61672:2013 standard. The meter measures and displays the equivalent continuous sound level and sound exposure within the selected time period, ideal for occupational noise measurements.

Data Logging & Precision Recording

Suitable for both measuring noise in real-time as well as capturing noise exposure over time. Condenser microphone for high accuracy and long-term stability. Built-in memory for recording sound and measurement results (including Start/Stop Time, %Dose, TWA). Low power consumption and USB port charging allow long-hour usage. 

Data Logging & Precision Recording

Suitable for both measuring noise in real-time as well as capturing noise exposure over time. Condenser microphone for high accuracy and long-term stability. Built-in memory for recording sound and measurement results (including Start/Stop Time, %Dose, TWA). Low power consumption and USB port charging allow long-hour usage. 

Feature

• IEC 61672-1:2013 Class 2 Standard
• 28-133 dB measurement range
• ±0.7 dB high accuracy
• 0.1 dB resolution
• 20-12.5k Hz frequency range
• A, C, Z frequency weightings
• Fast, Slow, Impulse, Peak time weightings
• RS232 Data Output / USB computer interface
• Data Logging & Record functions
• Measurement Report Printing
• Optional: Portable High-Speed Printer Kit

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Feature

• IEC 61672-1:2013 Class 2 Standard
• 28-133 dB measurement range
• ±0.7 dB high accuracy
• 0.1 dB resolution
• 20-12.5k Hz frequency range
• A, C, Z frequency weightings
• Fast, Slow, Impulse, Peak time weightings
• RS232 Data Output / USB computer interface
• Data Logging & Record functions
• Measurement Report Printing
• Optional: Portable High-Speed Printer Kit

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Where does Scarlet Sound Level Meter Apply

Construction
Orchestras
Road Construction
Airport
Police Force
Any Fields Care About Noise Dose
Specifications
ModelST-21D
Fulfils StandardIEC 61672:2013 Class 2
Dimensions310×72×32 mm
Normal frequency20 Hz~12.5 kHz
Measurement range28~133 dB
Measurement LevelZ(FLAT): 38 ~ 130dB / C peak: 145dB / Z(FLAT): peak: 145dB
Main Parameters of MeasurementLFp, LSp, LIp, Leq,t, Lpeak, Leq,T, LFmax, LFmin, LSmax, LSmin, LImax, LImin, SEL, Lex8h, LAVG, TWA, DOSE, Ln1, Ln2, Ln3, Ln4, Ln5, SD,Ts, Tm, Volt, E.
Display128×64 OLED
Weight0.4kg
ApplicationSound level meter/ Noise Dosimeter/Data logging & Precision recording(Opt)
Power Supplybattery 4×AAA or external power supply

A Class 1 Sound Level Meter is a noise measurement instrument that meets the requirements of IEC 61672-1:2002 (or an equivalent such as BS EN 61672-1:2003) to Class 1 performance.
This standard specifies two levels of performance, Class 1 and Class 2, with Class 1 being effectively more accurate. Within the standard are a set of performance criteria that an instrument must meet and each of these has a tolerance associated with it. The tolerances for Class 1 are tighter than for Class 2. For example, at the reference frequency of 1kHz, the tolerance limits for Class 1 are +/- 1.9dB and for Class 2 the tolerance is +/- 2.2dB.
A simple sound level meter that meets the standard may only provide Sound Pressure measurements whereas a much more sophisticated instrument may provide for the measurement of Sound Pressure, Leq and Peak Sound Pressure.For example, the Noise at Work Regulations which are used in the UK requires, as a minimum, the measurement of LAeq and LCPeak.

Whether you need a Class 1 or a Class 2 sound level meter will depend largely upon the application that you will be using the instrument for.
If you are working to an environmental noise standard then this may specify that the instrument should be Class 1. For example, ISO 20906:2009 “Unattended monitoring of aircraft sound in the vicinity of airports” states that “..shall conform to the electroacoustical performance specifications of IEC 61672-1 for a class 1 sound level meter.”
The Class 1 sound level meter tend to measure lower levels due the sensitivity of the microphone capsule. This is particularly relevant for environmental noise surveys where low noise levels are being measured. Finally, you may choose Type 1 for important legal applications as the evidence from the more accurate meter may be more convincing, even when the regulations do not demand it. Class 1 sound level meter is preferred for the design of cost-effective noise controls.

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