Flowserve Twin Screw Rotary - Manual (Page 10)

TWIN SCREW PUMPS. ORIGINAL USER INSTRUCTIONS. ENGLISH. 71569243 – 07/10
Page 7 of 53
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1.8 Specific machine performance
For performance parameters see section 1.5 Duty
conditions. When the contract requirement specifies
these to be incorporated into User Instructions these
are included here. Where performance data has been
supplied separately to the purchaser these should be
obtained and retained with these User Instructions if
required.
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 units driven by equipment other than
electric motors or units contained within enclosures,
see the accompanying information sheets and
manuals.
TWIN SCREW pump size Sound Pressure Level
dbA @ 1 m (3.3 ft)
Pump Speed
r/min
Sound Power Level
dBA re 1 pW
NA 77 1750 91
NC 70 1750 84
ND 82 1750 96
NE 84 1750 98
NF 86 1750 100
NFX 86 1750 100
NG 86 1750 100
NH 87 1750 101
NI 87 1750 101
NII 87 1750 101
NIM 87 1750 101
NIJ 87 1750 101
NJ 88 1750 102
NL 88 1750 102
NLX 85 1150 99
NM 86 1150 100
NP18 87 1150 101
NP24 87 1150 101