"...average reduction in noise of 2.5 dB at high idle and 6.5 dB at low idle."
Subject:
Sound Testing Results
Summary of Suppressor Performance Data:
"The results showed an average reduction in noise of 2.5 dB at high idle and 6.5 at low idle. . . We were very impressed by the results at low idle..."
The following data sheets are for the tests performed using the Wilkes and Mclean inline hydraulic noise and shock suppressor. The suppressor was attached to the output hose of a Vickers Inc., nine piston pump (Model No. PVE19R-30-C-10-339). The goal for the sound test was to reduce the sound inside the cab to well below 85dB. The test followed the ISO 6394 International Standard for measurements of airborne noise emitted by earth-moving machinery at the operator's position in a stationary test condition.
The results showed an average reduction in noise of 2.5dB at high idle and 6.5dB at low idle. We were very impressed by the results at low idle and will keep this product in mind when other sound problems show up.
Sound Testing Data With Sound Suppressor Installed
Date: May 13, 1998
Low wind
70 degrees Started time: 6:30 am
End Time: 9:00 am
High Idle 2193 RPM
Operating Pressure is 2500 psi
Initial Readings without Sound Suppressor Installed:
Left Ear
Right Ear
Average
.
87.2
88.5
87.9
.
Pressure
Left Ear
Right Ear
Average
Difference
2500
85.4
85.1
85.25
2.65
2400
84.5
84.9
84.70
3.20
2300
85.4
84.2
84.80
3.10
2200
85.0
85.3
85.15
2.75
2100
85.9
84.8
85.35
2.55
2000
86.0
85.6
85.80
2.10
1900
85.0
84.4
84.70
3.20
1800
85.7
85.3
85.50
2.40
1700
84.4
85.4
84.90
3.00
1600
84.9
85.0
84.95
2.95
1500
85.0
84.5
84.75
3.15
1400
84.3
84.7
84.50
3.40
1300
85.6
84.9
85.25
2.65
1200
86.3
86.4
86.35
1.55
1100
86.1
86.2
86.15
1.75
High Idle Average Sound Level Sound Level vs. Pressures
Low Idle 1104 RPM Operating Pressure is 2500 psi
Initial Readings without Sound Suppressor Installed
Left Ear
Right Ear
Average
.
83.9
87.7
85.8
.
Pressure
Left Ear
Right Ear
Average
Difference
2500
79.4
79.2
79.30
6.50
2400
77.7
80.2
78.95
6.85
2300
77.3
80.5
78.90
6.90
2200
78.5
79.1
78.80
7.00
2100
79.0
80.4
79.70
6.10
2000
78.7
79.4
79.05
6.75
1900
78.7
79.8
79.25
6.55
1800
78.6
80.1
79.35
6.45
1700
77.7
80.8
79.25
6.55
1600
77.2
78.6
77.90
7.90
1500
78.8
80.0
79.40
6.40
1400
79.8
81.3
80.55
5.25
1300
77.7
81.3
79.50
6.30
1200
81.8
81.2
81.50
4.30
1100
79.1
79.3
79.20
6.60
Low Idle with Sound Suppressor Sound Level (dB) vs. Pressure (psi)
