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Summary of Contents for G.R.A.S. 67SB
- Page 1 Instruction Manual 67SB Blast Probe According to ANSI S12.42 www.gras.dk LI0056 – Revision 28 May 2015...
- Page 2 Revision History Any feedback or questions about this document are welcome at gras@gras.dk. Revision Date Description 23 June 2011 First publication 20 April 2012 Revision. Added: In-situ calibration. 8 August 2012 Changed part number GU0212 references to GR1462. 28 May 2015 Tripod thread corrected to 1/4”...
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Page 3: Table Of Contents
Contents Introduction .................. 4 The 67SB Package ................ 5 Measurement Setups ..............6 Removing and Installing the Microphone ..........7 Disconnecting the Two Parts of the Tube ............7 Removing the Microphone Assembly ............8 Reinstalling the Microphone Assembly ............9 Calibration ................. -
Page 4: Introduction
Introduction The 67SB Blast Probe According to ANSI S12.42 is designed to meet the require- ments of a blast probe suitable for high-level impulse measurements as outlined in ANSI S12.42. The 67SB complies with ANSI S12.42 and IEC 61094-1. The 67SB consists of a sturdy aluminium tube and a flush-mounted 1/8-inch externally polarized pressure microphone (40DP) as sensor. -
Page 5: The 67Sb Package
The 67SB Package The 67SB Blast Probe According to ANSI S12.42 is delivered as a preassembled pack- age. The following table list all items delivered with the 67SB. Fig. 2 shows the 67SB in its travel case. Included Items Part Number Blast Probe According to ANSI S12.42 (includes microphone and... -
Page 6: Measurement Setups
±60 V/120 V to the preamplifier. The connection is via a 7-pin male LEMO at the rear end of the tube. The 40DP can handle a peak sound pressure of 174dB. The 67SB uses an externally polarized microphone and is not CCP compatible. G.R.A.S. -
Page 7: Removing And Installing The Microphone
Removing and Installing the Microphone This section describes how to remove and install the microphone, for example, when you need to calibrate it. The main user-accessible parts of the blast probe are shown in Fig. 5. The two tube parts are held in place with a short M2 hex screw (item 3) and an O-ring in a recess inside the front part (Item 1). -
Page 8: Removing The Microphone Assembly
Removing the Microphone Assembly The microphone is secured inside the front tube by a clamp and an M2 hex screw. When positioned in the clamp with the M2 hex screw tightened, the microphone assembly is properly secured. A guard ring below the protective grid ensures seating against the inner surface and that the diaphragm is flush with the outer surface of the probe. -
Page 9: Reinstalling The Microphone Assembly
Reinstalling the Microphone Assembly The steps for reinstalling the microphone assembly are basically the reverse of the steps for removing the assembly. The diaphragm of the microphone must be flush with the outer surface of the probe tube when mounted, as required by the ANSI S12.42 standard. The following ensures that this requirement is met: • The guard ring must be situated correctly on the microphone assembly. -
Page 10: Calibration
With the GR1462 External Calibration Adapter, you can calibrate the microphone in the 67SB without dismounting it. The adapter is mounted as shown in Fig. 9. An O-ring inside the adapter ensures a proper fit over the microphone. The correction factor is 0.04 dB. -
Page 11: Separate Calibration
Separate Calibration You can calibrate the microphone in-situ as described on page 10, but you can also calibrate it separately. In this case, no correction factor is needed. To calibrate the microphone, you must remove it from the probe tube: 1. -
Page 12: Technical Specifications
Technical Specifications Typical Performance The following diagram demonstrates the time domain of an impulse as measured by the 67SB. The peak measurement of 6000 Pa in this example is approximately 170 dB. Time Domain of Impulse 7000 6000 5000 4000 3000 2000... -
Page 13: Ordering Information
<0.1 dB (0 - 100 % RH) Ordering Information Included Items Part Number Blast Probe According to ANSI S12.42 (includes microphone and 67SB preamplifier in the probe housing, and a travel case) 1.5 mm Hex key YY0012 Calibration plug GR1423... -
Page 14: Accessories
Accessories The following items are optional for the 67SB and can be ordered separately. Item Part Number 1-Channel LEMO Power Module with gain, filters, and SysCheck 12AK generator 3 m LEMO extension cable AA0008 10 m LEMO extension cable AA0009 Intelligent Pistonphone...
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