VIacoustics ACCULAB RSS-101 Service manual

2021 RSS Manual all models.doc. Page 1 // 02/12/21
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2512 Star Grass Circle
Austin, TX 78745
(512-531-6442)
ACCULAB REFERENCE SOUND SOURCE MANUAL
For Laboratory and Field Noise Measurement Applications since 1982
ISO 6926 / ANSI S12.5 / AHRI-250 /AMCA 300 Compliant
CONTENTS:
SPECIFICATIONS ........................................................................................................................................2
CAUTION........................................................................................................................................................3
OPERATING INSTRUCTIONS: .................................................................................................................4
MAINTENANCE............................................................................................................................................ 5
NOMINAL SOUND POWER DATA...........................................................................................................8
CORRECTIONS...........................................................................................................................................13

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SPECIFICATIONS
NOMINAL ACOUSTICAL PERFORMANCE OVERVIEW
(See Nominal Sound Power Data section for tabular data)
Unit Type
RSS-
101
RSS-
400
RSS-500
RSS-
600
RSS-
700
RSS-101U
Applicability
Standard
SPL
Higher
SPL
Lower
Frequency
Ultra
SPL
Low
SPL
Ultrasound
A-Wtd PWL
dB re 1pW
86
93
86
105
65
*10kHz -
100kHz
PWL values assume 60 Hz AC power
Units used with 50 Hz AC power will have lower power output

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CAUTION
1. Keep hands and fingers, loose hanging clothing, jewelry, and access badges on lanyards
well clear of fan wheel. Clear a 6' (2m) diameter area of dust and loose paper objects since
air flows out of the fan wheel perimeter onto the room floor during normal RSS operation.
2. Plug into appropriate power source (check specific unit specifications). The fan will start
immediately. Extension cord length vs. minimum wire size: 100'- #16; 200'-#14 (115V).
3. The RSS motor is thermally protected (TP): If fan wheel ever fails to turn after electric
power is applied, DISCONNECT electric power before investigating. Operation may be
continuous for ambient air temperatures below 40º C. Run acoustical tests according to your
program requirements. Nominal Sound Power data in 1/3-octave and octave bands is found on
the next page. Check your current calibration report for data of your specific unit.
4. Disconnect the RSS from electrical power when not in use.
5. Place RSS in its shipping container when not in use for extended periods.(Storage on its
side or in the RSS case will unload and prevent distortion of the resilient feet during long-term
storage).
WARNING: STAY CLEAR OF UNIT WHEN OPERATING!

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OPERATING INSTRUCTIONS:
UNPACKING-
Before placing the RSS into use, please observe the following Precautions.
1. Remove the RSS from the case by pulling it upward by its frame, never the fan wheel.
2. Place it upright on its rubber feet on a firm floor or bench. The feet isolator bolt heads
should protrude above the steel plate by 1/8” – 3/16”. Adjust as needed
3. Inspect fan wheel for uniformity and firmness of shaft attachment. Use 4 mm Allen key
supplied to torque both wheel hub set screws to 30 inch-pounds if in doubt. (Access Allen
screw heads between fan wheel blades). Before plugging into AC power check that the fan
wheel turns freely and evenly by hand.
ACOUSTICAL APPLICATION-
Set the RSS on its feet at the desired location. Maintain its spacing from vertical surfaces
according to your applicable acoustical test requirements. The floor under the RSS should be
firm and not prone to act as a "sounding board" which can emit vibration induced sounds. The
spring-isolated feet should prevent this for wood joist floors. If the RSS is set on an elevated
flat horizontal surface that “baffle” surface should be at least 3' (1m) square or round to assure
that the calibrated sound power is emitted into the test area. That baffle should not be so light
(e.g. thin sheet metal) as to act as a sounding board despite the isolator spring action. If
vibration induced sound is still found to be radiated from such a thin sheet, then use additional
cushioning such as small foam rubber pads 1/2" to 1" thick under the feet of the RSS or use a
more massive baffle plate in place of, or over, the sheet metal.
Check RPM with a tachometer or strobe and compare to the nominal values in this manual or
the calibration documentation for your specific unit. If possible, operate the RSS on a variac
and adjust the input voltage as to match the nominal or calibrated RPM for the unit.
Generally, the RPM of an RSS will drop slightly after warming up for about 5 minutes. If the
stabilized RPM is lower than expected, then the AC line voltage source may be too low, or if
an extension cord is used, it may need to be shorter or have heavier gauge wire.
Operation at other RPM values can be corrected according to Corrections section of this
document.
WARNING: STAY CLEAR OF UNIT WHEN OPERATING!

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MAINTENANCE
FAN WHEEL SECURITY-After several hours of operation, inspect fan wheel for security of
attachment to the shaft. There are two Allen-head screws, which secure the fan wheel to the 1/2"
shaft. The first indication of looseness of these screws is a slight "rattling" sound emitted from the
wheel during start-up or normal operation. Use the 4mm Allen key (attached to one of the motor
bolts) to tighten these screws per the "FAN WHEEL REPLACEMENT" procedure, below.
FAN WHEEL CONDITION-The fan wheel geometry and RPM precisely determine the sound level
emitted by the RSS. Fan wheel distortions and dust accumulation can alter the sound output. Dust
can be removed with a dry clean brush. Be careful not to dislodge the ½” surge band located around
the top inside of the fan wheel. Substantial fan wheel and surge band repairs may alter the sound
field, and recalibration is advised.
FAN WHEEL REMOVAL-It is strongly advised that the fan wheel not be removed from the motor
shaft. However, if maintenance procedures necessitate this, then proceed carefully as follows. Be
aware that removal may require some effort since a burr may have been formed under an Allen screw
on the motor shaft.
Extreme caution is necessary to avoid damaging the fan wheel, Allen screws and motor
shaft. Loosen the Allen screws two turns counterclockwise. Press the fan wheel upward by hand with
a few pounds (1 kG) force. If it does not come off immediately, then insert a 3/8" (9 - 12 mm)
diameter rod down into the shaft hole and tap it lightly with a hammer while a second person lifts
upward on the Fan wheel with 10 lbs (5 kG) force. When clear of the motor shaft, the wheel can be
slipped upward and to the side to clear the frame. Retain and replace the lock washer spacer on the
shaft. This spacer prevents contact of the Fan wheel to the motor support.
FAN WHEEL REPLACEMENT-
1. With a fine machinist’s file, clear any burrs left by tightened Allen screws from the shaft's
curved (not flat) surface.
2. Verify that the Allen screws are backed out far enough to clear both shaft flats.
3. Align the wheel with an Allen screw facing each flat. Slip the Fan wheel down the 1/2" motor
shaft with lessthan 2 lbs (1 kG) force. If it binds, do not force it further
4. Remove it, thoroughly file all shaft burrs smooth.
5. Back out the Allen screws to clear the entire wheel bore
6. By hand, pass the back end of a 1/2” (12.7mm) drill bit up through motor end of the wheel
bore.
7. Center the hub on the drill spiral. Rotate the drill to clear hub bore burrs
8. Try installing the Fan wheel on the shaft again. If it still does not go onto the shaft smoothly
try step 4 and 6 again.
Align the fan wheel to face one set screw at the large shaft flat while the other screw falls on
the lesser ground flat. Press the down on the fan wheel with about 2 pounds (1 kg) force and turn in
the Allen screw on the larger flat of the shaft while rapidly rotating the fan wheel fore and aft a few
degrees to assure that this Allen screw is seating on the flat's lowest point.
Torque this Allen screw to at least 30 to 40 inch-pounds (0.35 to 0.45 kg-m). Turn in the
second Allen screw and torque it to 20 to 30 inch-pounds (0.25 to 0.35 kg-m). Caution: Allen key
must be fully inserted into the Allen screw head for this final torque. Improper key seating or torque
applied beyond these values will damage the Allen screw**
WARNING: STAY CLEAR OF UNIT WHEN OPERATING!

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MOTOR ELECTRICAL SYSTEM-The electric motor is a capacitor start induction motor with an
internally switched starting capacitor and with internal thermal protection. Service cord replacement
is allowed. Use 16 gauge or heavier flexible copper service cords not more than 12 feet (3.5 m) long.
Bayonet terminals are used. If installing replacement cord has lug nut connectors, use extreme
caution in applying torque to the terminal screw connector-nuts. Rotation of the terminal studs will
cause internal motor shorts and motor burnout. Jumper connections internal to the motor (e.g. red vs.
black) shall not be changed during inspections or service wire replacement because the direction of
rotation will change. The direction of fan wheel rotation (counter - clockwise looking down into
the unit) is mandatory for proper calibration.
MOTOR SECURITY-The motor bolts and lock nuts need not normally be inspected unless repair or
inspection requiring removal of the motor is performed. Upon re-assembly, torque the motor bolts and
lock nuts to 8 ft-lb. (1.1 kg-m) before placing the RSS into routine use.
MOTOR LUBRICATION- Oil ports are not provided. This RSS motor has ball bearings that should
operate quietly for at least 10 years. After 10 years if any squeaking sound is heard from the bearings,
the motor end bells may be removed, and the bearings lubricated by massaging new grease into the
bearing races.
CARRYING FRAME-The frame of the RSS is reinforced with lateral braces to prevent frame
bending in shipment. The motor and fan should stand erect + 3 degrees within the frame. If the motor
bolts have loosened, then realign and tighten bolts per "MOTOR SECURITY" above. If the motor
support or frame is bent, but the motor/fan wheel axis tilt is less than 4 degrees, no corrective action
is necessary. Larger deformations or bent frame members should be corrected by good metal (steel)
shop practices after removal motor/fan wheel as a unit by unfastening the four motor bolts. Take
precautions to NOT apply any deforming forces to fan wheel during removal, storage, and
replacement. Store motor/fan wheel on a short 1-1/2" thick board since fan wheel radius is 1-1/2"
greater than motor shaft height. Replace motor/fan wheel per “MOTOR SECURITY".
SPRING ISOLATOR FEET: Each retainer bolt head projects above and clears the frame plate by
1/8” to 3/16” when the RSS stands on its feet. Adjust by rotating the bolt if needed.
PERIODIC ACOUSTICAL CHECK AND CALIBRATION: The RSS should produce a constant
sound field indefinitely as long as proper electrical power is applied, and no damage has occurred to
the unit. However, significant fan wheel or motor damage and/or dust accumulation can alter the
sound power output. Dust can be removed as described in FAN WHEEL CONDITION.
Periodic acoustic checks of the RSS as described in ISO 6926/ANSI S12.5 section 5.6.3 at least
every 6 months or any time the unit appears to have incurred damage. Units that are regularly
transported to field locations may need to have the period check performed more frequently.
Recalibration according to ISO 6926 is advised when fan wheel or surge band damage have been
repaired, when fan wheel RPM deviates constantly more that 1 % from the RPM reported at the
calibration voltage or when more than ten (10) years have elapsed since the last calibration.
Calibration should be performed in a laboratory operating in accordance with ISO 6926/ANSI S12.5,
Free Field over a Reflecting Plane.
SERVICE DIFFICULTY, SHIPPING AND FACTORY REPAIRS: In case of difficulties, contact
VIacoustics for further help and instructions. Do NOT load this bare-framed instrument surrounded
by only bubbles or pellets, as the fan wheel can be damaged in this environment. It is recommended
that RSS units be shipped in the robust carrying case/shipping container provided by VIacoustics.
WARNING: STAY CLEAR OF UNIT WHEN OPERATING!

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CALIBRATION
Periodic acoustic checks of the RSS as described in ISO 6926/ANSI S12.5 section 5.6.3 at least
every 6 months or any time the unit appears to have incurred damage. Units that are regularly
transported to field locations may need to have the periodic check performed more frequently. A
periodic check both before and after transporting the RSS assures that the RSS continues to operate
at its calibrated sound power.
The periodic check should be conducted using at least four (4) fixed measurement positions relative
to the RSS in the same test environment. If the standard deviation of the average of the sound
pressure levels at the measurement positions of the periodic check measurements over time exceeds
the values shown below, the RSS should be re-calibrated per ISO 6926/ANSI S12.5
1/3 OB Center
Frequency (Hz)
Maximum Standard Deviation
of Repeatability (dB)
50 Hz - 80 Hz
2.3
100 Hz –160 Hz
1.1
200 Hz –20 kHz
(or max frequency of
use)
0.6
Recalibration according to ISO 6926 is advised when fan wheel or surge band damage has been
repaired, when fan wheel RPM deviates constantly more that 1 % from the RPM reported at the
calibration voltage or when more than ten (10) years have elapsed since the last calibration.
Calibration should be performed in a laboratory that is accredited per ISO 17025 and conducting the
calibration in accordance with ISO 6926/ANSI S12.5, Free Field over a Reflecting Plane.

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NOMINAL SOUND POWER DATA
Nominal Sound Power (PWL): RSS 101 Series
1/3 Octave Band
(Hz)
Sound Power
(dB re 1 pW)
Octave Band
(Hz)
Sound Power
(dB re 1 pW)
50
74.4
63
77.2
63
72
80
69.7
100
70.2
125
75.9
125
71.2
160
71.8
200
72.5
250
77.2
250
72.5
315
72.3
400
72.2
500
77.5
500
73.1
630
72.9
800
73.1
1000
79.5
1000
75
1250
75.7
1600
75.5
2000
79.3
2000
74.9
2500
73
3150
72.4
4000
76.8
4000
71.8
5000
71.7
6300
70.7
8000
73.7
8000
69
10000
65.5
12500
62.2
16000
64.7
16000
59.1
20000
56.9
A-Weighted PWL: 85.0 dB(A) re 1 pW
OTHER SPECIFICATIONS
Size: 240 x 240 x 410 mm (10" x 10" x 16")
Weight: 12 kg (26 lbs.)
RPM: 3570
Electrical Source: 115 V AC, single phase, 60 Hz, 5.6 A

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Nominal Sound Power (PWL): RSS 400 Series
1/3 Octave Band
(Hz)
Sound Power
(dB re 1 pW)
Octave Band
(Hz)
Sound Power
(dB re 1 pW)
50
79.1
63
82.7
63
76.6
80
77.7
100
78.9
125
84.2
125
79.6
160
79.8
200
80.3
250
84.9
250
80.1
315
79.9
400
79.9
500
84.5
500
79.4
630
80
800
81.2
1000
87.5
1000
83
1250
83.6
1600
84
2000
88
2000
83
2500
82.3
3150
81.4
4000
85.5
4000
80.6
5000
80.3
6300
79.4
8000
82.5
8000
77.7
10000
75.1
12500
72.2
16000
74.8
16000
69.2
20000
67.1
A-Weighted PWL: 93.4 dB(A) re 1 pW
OTHER SPECIFICATIONS
Size: 240 x 240 x 410 mm (10" x 10" x 16")
Weight: 12 kg (26 lbs.)
RPM: 3460
Electrical Source: 115 V AC, single phase, 60 Hz, 5.6 A

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Nominal Sound Power (PWL): RSS 500 Series
1/3 Octave Band
(Hz)
Sound Power
(dB re 1 pW)
Octave Band
(Hz)
Sound Power
(dB re 1 pW)
50
63
80
72.9
72.7
72.6
63
77.5
100
125
160
72.3
71.9
71.8
125
76.8
200
250
315
71.9
72.4
73.0
250
77.2
400
500
630
73.5
73.5
75.1
500
78.8
800
1000
1250
76.5
77.2
76.4
1000
81.5
1600
2000
2500
75.1
73.9
72.8
2000
78.8
3150
4000
5000
72.5
72.1
71.9
4000
76.9
6300
8000
10000
70.9
68.7
66.1
8000
73.8
12500
16000
20000
63
61
59
16000
66
A-Weighted PWL: 85.7 dB(A) re 1 pW
OTHER SPECIFICATIONS
Size: 330 x 330 x 380 mm (13" x 13" x 15")
Weight: 13 kg (29 lbs.)
RPM: 1725
Electrical Source: 115 V AC, single phase, 60 Hz, 5.8 A

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Nominal Sound Power (PWL): RSS 600 Series
1/3 Octave Band
(Hz)
Sound Power
(dB re 1 pW)
Octave Band
(Hz)
Sound Power
(dB re 1 pW)
50
63
80
83.9
85.6
87.8
63
90.8
100
125
160
90.7
91.0
91.2
125
95.7
200
250
315
90.7
90.4
90.7
250
95.4
400
500
630
90.2
90.0
91.5
500
95.4
800
1000
1250
93.1
94.1
93.8
1000
98.4
1600
2000
2500
93.2
93.6
94.1
2000
97.5
3150
4000
5000
93.6
92.7
91.7
4000
90.0
6300
8000
10000
91.1
89.7
88.3
8000
94.6
12500
16000
20000
86
84
81
16000
89
A-Weighted PWL: 104.4 dB(A) re 1 pW
OTHER SPECIFICATIONS
Size: 330 x 330 x 380 mm (13" x 13" x 15")
Weight: x kg (X lbs.)
RPM: 3450
Electrical Source: 230 V AC, single phase, 60 Hz, 10.4 A

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Nominal Sound Power (PWL): RSS 700 Series
1/3 Octave Band
(Hz)
Sound Power
(dB re 1 pW)
Octave Band
(Hz)
Sound Power
(dB re 1 pW)
50
63
80
62
60
60
63
66.0
100
125
160
59.3
58.6
58.4
125
63.5
200
250
315
58.2
57.8
57.8
250
62.7
400
500
630
57.9
57.8
57.4
500
62.5
800
1000
1250
57.5
58.4
57.5
1000
62.6
1600
2000
2500
57.2
56.9
56.5
2000
61.6
3150
4000
5000
55.4
53.9
52.5
4000
58.9
6300
8000
10000
50.9
48.5
45.8
8000
53.6
12500
16000
20000
43
41
37
16000
46.0
A-Weighted PWL: 67.8 dB(A) re 1 pW
OTHER SPECIFICATIONS
Size: 250 x 250 x 250 mm (l0" x 10" x 10")
Weight: X kg (x lbs.)
RPM: 1725
Electrical Source: 115 V AC, single phase, 60 Hz, 2.6 A

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CORRECTIONS
Nominal values are corrected for Reference Meteorological Conditions of 23.0 C, 101.325 kPa and 50%
RH and have been adjusted for air absorption at the time of the calibration per ISO 3745/ANSI S12.55
Equation 19 and ISO 9613-1:1993. Actual RSS sound power level emitted at a test site will depend on
temperature, barometric pressure, and humidity at the test site. Adjustments to the calibrated sound power
can be calculated as described in ISO 3745 Equation 16 and ISO 9613-1.
The table below may be used to correct for variance between RPM read from a tachometer or
strobe and the RPM stated in calibration documentation. Or, if available, a variable transformer
may be used adjust the input AC voltage as to obtain the RPM stated in calibration
documentation.
Frequency Range:
12 –40 Hz
50 –160 Hz
200 –10,000 Hz
test RPM - cal RPM
Correction, dB
+30
+o.1
+o.2
+o.3
+20
+o.1
+o.2
+o.2
+10
-0-
+o.1
+o.1
Cal RPM ( )
-0-
-0-
-0-
-10
-0-
-o.1
-o.1
-20
-o.1
-o.2
-o.2
-30
-o.1
-o.2
-o.3
1. Measure the RPM with an optical tachometer or strobe
2. If the observed RPM that occurred during your test departed more than 10 RPM from the value at
calibration, then correct the sound power values according to the following table. The emitted sound
power of the RSS unit increases at higher fan RPM and decreases at lower fan RPM.