9 noise level, Typical sound pressure level l, At 1 m reference 20 µ pa, dba – Flowserve NMD User Manual
Page 9
NMD, NMAD USER INSTRUCTIONS ENGLISH 71576436 - 11/09
Page 9 of 40
1.9 Noise level
Attention must be given to the exposure of
personnel to the noise, and local legislation will
define when guidance to personnel on noise
limitation is required, and when noise exposure
reduction is mandatory. This is typically 80 to 85
dBA.
The usual approach is to control the exposure time
to the noise or to enclose the machine to reduce
emitted sound. You may have already specified a
limiting noise level when the equipment was
ordered, however if no noise requirements were
defined, then attention is drawn to the following table
to give an indication of equipment noise level so that
you can take the appropriate action in your plant.
Pump noise level is dependent on a number of
operational factors, flow rate, pipework design and
acoustic characteristics of the building, and so the
values given are subject to a 3 dBA tolerance and
cannot be guaranteed.
Similarly the motor noise assumed in the “pump and
motor” noise is that typically expected from standard
and high efficiency motors when on load directly
driving the pump. Note that a motor driven by an
inverter may show an increased noise at some
speeds.
If a pump unit only has been purchased for fitting
with your own driver then the “pump only” noise
levels in the table should be combined with the level
for the driver obtained from the supplier. Consult
Flowserve or a noise specialist if assistance is
required in combining the values.
It is recommended that where exposure approaches
the prescribed limit, then site noise measurements
should be made.
The values are in sound pressure level L
pA
at 1 m
(3.3 ft) from the machine, for “free field conditions
over a reflecting plane”.
For estimating sound power level L
WA
(re 1 pW) then
add 17 dBA to the sound pressure value.
Typical sound pressure level L
pA
at 1 m reference 20 µPa, dBA
3 550 r/min
2 900 r/min
1 750 r/min
1 450 r/min
Motor size
and speed
kW (hp)
Pump
only
Pump and
motor
Pump
only
Pump and
motor
Pump
only
Pump and
motor
Pump
only
Pump and
motor
<0.55(<0.75)
72
72
64
65
62
64
62
64
0.75 (1)
72
72
64
66
62
64
62
64
1.1 (1.5)
74
74
66
67
64
64
62
63
1.5 (2)
74
74
66
71
64
64
62
63
2.2 (3)
75
76
68
72
65
66
63
64
3 (4)
75
76
70
73
65
66
63
64
4 (5)
75
76
71
73
65
66
63
64
5.5 (7.5)
76
77
72
75
66
67
64
65
7.5 (10)
76
77
72
75
66
67
64
65
11(15)
80
81
76
78
70
71
68
69
15 (20)
80
81
76
78
70
71
68
69
18.5 (25)
81
81
77
78
71
71
69
71
22 (30)
81
81
77
79
71
71
69
71
30 (40)
83
83
79
81
73
73
71
73
37 (50)
83
83
79
81
73
73
71
73
45 (60)
86
86
82
84
76
76
74
76
55 (75)
86
86
82
84
76
76
74
76
75 (100)
87
87
83
85
77
77
75
77
90 (120)
87
88
83
85
77
78
75
78
110 (150)
89
90
85
87
79
80
77
80
150 (200)
89
90
85
87
79
80
77
80
200 (270)
1
1
1
1
85
87
83
85
300 (400)
87
90
85
86
1 The noise level of machines in this range will most likely be of values which require noise exposure control, but typical values are inappropriate.
Note: for 1 180 and 960 r/min reduce 1 450 r/min values by 2 dBA. For 880 and 720 r/min reduce 1 450 r/min values by 3 dBA.