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Summary of Contents for GRAS 50GI
- Page 1 G R A S SOUND & VIBRATION Skovlytoften 33, 2840 Holte, Denmark www.gras.dk gras@gras.dk...
- Page 2 Intensity Probe Type 50GI CCP Intensity Probe Type 50GI Revision 6 June 2014 G.R.A.S. SOUND & VIBRATION Page 2...
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Page 3: Table Of Contents
Intensity Probe Type 50GI CONTENTS Introduction ........... . . 3 Description . -
Page 4: Introduction
Measurements with Pairs of Pressure Sensing Microphones, 1993 for Class 1 sound intensity probes. Fig. 1.1 The CCP Intensity Probe Type 50GI Main Features The CCP Intensity Probe Type 50GI is a simple-to-use and reliable probe designed with the fol- lowing features: • Complete Sound Intensity Probe for noise source location and sound power measurements • Easy connection to analyzer equipment with IEPE (CCP) inputs • Complete ready-to-use kit delivered in a carrying case... -
Page 5: Delivered Components
• Preamplifiers Type 26CB-Set (see section 2.2) • Four solid spacers of various lengths and a spacer cup (see section 2.3) • Probe handle. As shown in Fig. 2.1, the Type 50GI is delivered in a carrying case complete with microphones, preamplifiers, and standard accessories. Fig. 2.1 The components delivered with the Type 50GI. See also Fig. 2.2. G.R.A.S. SOUND & VIBRATION... - Page 6 Intensity Probe Type 50GI G.R.A.S. SOUND & VIBRATION Page 6...
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Page 7: Microphones
The microphones (Fig. 2.3) are ½″ prepolarized free-field condenser microphones with high sensitivity and a uniquely-designed pressure equalization system that ensures extremely well- defined phase characteristics. The microphones and preamplifiers are mounted onto the end of the telescopic arm of the Probe handle. To cover the full frequency range from 30 Hz to 10 kHz, the Type 50GI is delivered with four solid interchangeable spacers for spacing the microphones at 12 mm, 25 mm, 50 mm, and 100 mm. Fig. 2.3 Showing similar pairs of phase-matched ½″ microphone cartridges: Above: Type 40GK which includes spacers and three adapters for ¼″... -
Page 8: Spacers
RA0264 GR0040 RA0266 RA0265 RA0263 With ¼" Mics. Type 40BI and 6mm spacer (GU0020) Fig. 2.5 Showing the various spacers and the spacer cup supplied with the Type 50GI 12 mm (RAA0266) 12mm (GU0005) 25mm (RAA0265) 25mm (GU0004) 50mm (GU0003) -
Page 9: Assembly
Intensity Probe Type 50GI Assembly Assembling the Probe The Intensity Probe can be assembled in either a straight setup or a symmetrical setup: • The straight setup (Fig. 3.1), is for intensity measurements close to surfaces and general source location measurements. • The symmetrical configuration (Fig. 3.2), is ideal for sound power measurements, for ex- ample according to international standard ISO 9614-2 “Acoustics - Determination of sound power levels of noise sources using sound intensity”... - Page 10 Intensity Probe Type 50GI Straight setup (Fig. 3.1) ¼″″ CCP Preamplifier Type 26CB Symmetrical setup (Fig. 3.2) Straight Adapter Right-angled Adapter RA0003 Type 40GI ¼″ CCP Preamplifier Type 26CB Spacer RA0266 Matched pair of microphones Type 40GI Spacer Cup GR0040 Right-angled Adapter RA0001 ¼″ CCP Preamplifier Type 26CB Fig.
- Page 11 Intensity Probe Type 50GI 7. Now assemble the probe head by pressing the free end of the spacer (mounted on the one microphone) into the spacer cup mounted on the other microphone: Push together Spacer cup Spacer Microphone Fig. 3.4 Assembling the probe head (shown for the symmetrical setup) 8. Mount the probe head by sliding either of the preamplifiers into the clamp (which can be...
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Page 12: Using The Windscreen
Fig. 3.7 Example of completely assembled Probe Type 50GI (symmetrical setup with 25-mm spacer) Using the Windscreen The Sound Intensity Probe Type 50GI includes an elliptical windscreen (AI0001) which can be used whenever making outdoor measurements or when making indoor measurements in the presence of bulk air movements. Use it only when measurements are influenced by wind. It gives good protection at wind speeds greater than 0.5 m/s and can reduce pressure fluctuations... -
Page 13: Calibration
Intensity Probe Type 50GI Calibration Checking the Sensitivity and P-I Index using a Pistonphone 4.1.1 Checking the Sensitivity Check the sensitivity of the microphones using a Pistonphone Type 42AP (recommended) or Type 42AA. Refer to the manual supplied with the pistonphone for instructions on using the pistonphone. -
Page 14: Checking The Probe's P-I Index Using An Intensity Calibrator
Intensity Probe Type 50GI Checking the Probe’s P-I Index using an Intensity Calibrator The P-I (Pressure Intensity) index of the sound intensity microphone pair and preamplifiers can be checked using the Intensity Calibrator Type 51AB - proceed as follows: 1. Mount the intensity microphones on their preamplifiers. 2. Connect the preamplifier outputs to the sound-intensity analyzer 3. Insert the microphones into the holes at the ends of the Intensity Calibrator, making sure to push then all the way in. -
Page 15: Typical Application Setup
Intensity Probe Type 50GI Typical Application Setup Connect the probe to the Sound Intensity Analyzer via the appropriate adapter cable. 080021 Example of DUT: washing mashine Sound Intensity analyzer 080028 Fig. 5.1 Example of application setup: measuring the sound intensity of a washing mashine 080001 G.R.A.S. SOUND & VIBRATION Page 15... -
Page 16: Specifications
Intensity Probe Type 50GI Specifications 2 x Sound intensity microphone Type 40GK:½″ free-field Frequency response and phase matching: IEC 61043 Class 1 1 x ¼″ CCP Preamplifier Type 26CB-Set: Phase-matched Weight: 0.3 kg (0.7 lbs) Frequency range: with 100-mm spacer: 30 Hz - 1 KHz with 50-mm spacer: 80 Hz - 1.5 KHz with 25-mm spacer: 120 Hz - 5 KHz with 12-mm spacer: 200 Hz - 10 KHz See also Product Data for Type 40GK and Type 26CB. G.R.A.S. SOUND & VIBRATION Page 16... -
Page 17: Optional Accessories
Intensity Probe Type 50GI Accessories Accessories included Microphone set Type 40GK comprising: 2 x ½″ Free-field Sound Intensity Microphone Type 40GI Spacer, 100 mm RA0263 Spacer, 50 mm RA0264 Spacer, 25 mm RA0265 Spacer, 12 mm RA0266 Straight adapter RA0003 Angled adapter RA0001 1 x ¼″ CCP Preamplifiers Type 26CB-Set 3-m cable (supplied...
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