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Pump Noise Calculator

The full chain in one pass: brake power → dBA at BEP (1–2 stage vs multistage curves), part-load correction, octave-band split, distance attenuation (free field, −6 dB per doubling), multi-source energy sum with driver and gearbox — then an OSHA traffic light with the allowed exposure time. A pumpXSolver engineering tool.

Active stage-count curve OSHA 90 dBA line Current duty

Results

Octave bands — pump @ duty, 1 m

① Pump source — stages & power

② Duty & site — load and distance

Duty flow, % of BEP70 %
Staircase: +4/+3/+2/+1 dB deep part-load · 0 at BEP · +2 in runout

③ Other sources — dBA @ 1 m, 0 = off

How it works

Each link of the chain is simple; the value is in running them in the right order — power to level, level to duty correction, duty level to bands, and every source combined the energy way before the exposure verdict.

1 · Sound pressure level and the power correlation

$$L_p \;=\; 20\,\lg\frac{p}{p_0}\;\;[\text{dB}], \qquad p_0 = 20\;\mu\text{Pa}, \qquad L_{tot} \;=\; 10\,\lg\sum_i 10^{L_i/10}$$
SymbolMeaningUnit
\(L_p\)sound pressure level (dBA = A-weighted)dB
\(L_i\)level of the i-th incoherent sourcedB
\(r\)distance from the sourcem
\(C_i,\,T_i\)actual / permitted exposure time at level ih
\(BHP\)brake (shaft) power at BEPhp / kW

The overall dBA at BEP comes from a brake-power correlation digitized onto two curves — 1–2 stage and multistage (≥ 3) — log-interpolated between anchor points. Figure-read precision is about ±2 dBA; treat single digits accordingly. Off-BEP duty shifts the level along a staircase: +4/+3/+2/+1 dB deep part-load, 0 in the 75–125% band, +2 in runout.

2 · Octave bands

$$L_{band} \;=\; L_{overall} - \Delta_{band}$$

Nine standard bands from 31.5 Hz to 8 kHz. Corrections (subtract from the pump's overall level): 1–2 stage — 4, 6, 4, 3, 4, 5, 6, 9, 12 dB; multistage — 11, 9, 7, 5, 3, 3, 3, 7, 12 dB. Multistage pumps carry less low-frequency energy, which is why their low-band corrections are larger.

3 · Distance attenuation

$$L_p(r_2) \;=\; L_p(r_1) - 20\,\lg\frac{r_2}{r_1}$$

Free-field radiation from a point-like source: −6 dB per doubling of distance. Indoors the reverberant field flattens this — treat the free-field number as the optimistic bound.

4 · Combining sources

$$L_{tot} = 10\,\lg\bigl(10^{L_1/10} + 10^{L_2/10} + \dots\bigr)$$

Levels add by energy, never arithmetically: two equal sources give +3 dB, a 10 dB-different pair adds just +0.4 dB. Example: 82 + 88 + 91 dBA → 93.1 dBA. The tool sums the pump at duty with the driver and gearbox levels you enter (0 switches a source off).

5 · OSHA exposure judgement

$$\text{Dose} \;=\; \sum_i \frac{C_i}{T_i} \;<\; 1 \quad\text{is compliant}, \qquad T = \frac{8}{2^{(L-90)/5}}\;\text{h}$$
Workplace levelAllowed timeStatus
< 85 dBAfull shift🟢 below the action level
85 – 90 dBAfull shift + hearing conservation program🟡 action level
90 – 115 dBA90→8 h · 95→4 h · 100→2 h · 105→1 h · 110→0.5 h · 114→0.3 h🟡 hearing protection required
≥ 115 dBA15 min/day at 115; above it, none🔴 ceiling

Each −5 dB doubles the allowed time. The verdict reports the allowed hours and the dose your shift length implies.

Worked anchor — the page opens on it

A 329 BHP double-suction pump at 70% of BEP flow, a 91 dBA gearbox and an 82 dBA turbine on the same foundation. The digitized curve reads 85.3 dBA @ BEP (the handbook figure-read is 87 — same answer within the ±2 dBA reading precision). Part-load adds +1 dB → 86.3; the energy sum with 82 and 91 gives 92.7 dBA @ 1 m vs the handbook's 93 by the figure-read path. OSHA: above the 90 dBA PEL → 🟡 hearing protection, allowed exposure ≈ 5.5 h/day (an 8 h shift ≈ 145% dose). Octave split of the pump level: 82, 80, 82, 83, 82, 81, 80, 77, 74 dB from 31.5 Hz to 8 kHz.