How do you calculate hydraulic efficiency here?

Divide the affected units by the total units and multiply by 100. With 8 affected out of 250 total, that is 8 / 250 = 3.2%. The gap to your 95% target is 91.8 points.

Is this the same as pump hydraulic efficiency (water power over shaft power)?

No. This tool computes a count-based rate — flagged units divided by total. Thermodynamic pump hydraulic efficiency compares delivered water horsepower to input brake horsepower and needs flow, head, and power inputs instead.

What is a good affected-unit rate on a pump assembly line?

For first-pass hydraulic test on medium-run centrifugal pumps, most cells target under 2-3% affected. The example 3.2% is slightly above a tight target, which is why the gap to a 95% goal reads 91.8 points.

Why is the gap to target so large in the example?

Because the rate (3.2%) and the target (95%) are measuring different things in the default setup — a low affected rate versus a high pass-rate target. Set your target to the affected-rate ceiling you want (e.g. 3%) so the gap reads meaningfully.

Affected rate vs first-pass yield — what is the difference?

They are complements. If 3.2% of units are affected, first-pass yield is roughly 96.8%. Use affected rate when you want to trend the problem; use yield when reporting the good-build percentage upward.

How many units should I count before trusting the rate?

With small lots the rate is noisy — one bad casing in 20 is 5%. Aim for at least 100-250 units, like the 250 in the example, before you act on a shift in the percentage.

Pump, Compressor & Rotating Equipment Assembly calculator

Hydraulic Efficiency Calculator

Hydraulic efficiency on a pump assembly line tracks what share of your built units fall into a flagged category — such as units failing the flow or head test versus the total run. Test techs, cell leads, and quality engineers on pump and compressor lines use it to convert raw counts into a rate they can trend and compare against a target. It matters because a rising affected-unit share on rotating equipment usually points upstream to impeller clearance, seal seating, or balance issues that get exponentially more expensive to chase after ship. Expressing the count as a percentage against a benchmark tells you at a glance whether the cell is holding standard or drifting.

What this calculator does

Hydraulic efficiency on a pump assembly line tracks what share of your built units fall into a flagged category — such as units failing the flow or head test versus the total run.
Use it when hydraulic efficiency in pump, compressor and rotating equipment assembly needs a clean rate and gap-to-target you can put on a tier board.
It divides affected units by total units to produce a percentage, then subtracts that rate from your target to show the gap in points.

Formula used

Hydraulic Efficiency rate = affected amount ÷ total amount
Gap to target = target rate - calculated rate

Inputs explained

Rejected or affected units:
Total units inspected:
Target efficiency rate:

How to use the result

Use it at end of shift or per build lot to convert defect or affected counts into a trendable rate and measure distance from your quality target.
It treats every affected unit equally and ignores severity, so eight minor cosmetic flags and eight scrapped casings read the same — weight or segment your counts if failure cost varies.

Current U.S. benchmarks

Industrial electricity averages 8.66 cents per kWh across the U.S. (EIA, Apr 2026), up 5.5% from a year earlier. Energy-intensive steps carry this directly into unit cost.
Manufacturing hourly earnings average $30.27 (BLS, Jun 2026), up 4.4% from a year earlier. Median machinist pay is $28.24/hr (OEWS 2025), with state medians on each state page. Manufacturers have 529k open positions nationally (BLS JOLTS).
Steel mill PPI stands at 348.53 (BLS, May 2026), up 6.7% from a year earlier. New factory orders are up 2.3% year over year (Census).
The U.S. has 21,668 machinery manufacturing establishments employing about 1,086,146 workers (Census County Business Patterns, 2023).

Common questions

How do you calculate hydraulic efficiency here? Divide the affected units by the total units and multiply by 100. With 8 affected out of 250 total, that is 8 / 250 = 3.2%. The gap to your 95% target is 91.8 points.
Is this the same as pump hydraulic efficiency (water power over shaft power)? No. This tool computes a count-based rate — flagged units divided by total. Thermodynamic pump hydraulic efficiency compares delivered water horsepower to input brake horsepower and needs flow, head, and power inputs instead.
What is a good affected-unit rate on a pump assembly line? For first-pass hydraulic test on medium-run centrifugal pumps, most cells target under 2-3% affected. The example 3.2% is slightly above a tight target, which is why the gap to a 95% goal reads 91.8 points.
Why is the gap to target so large in the example? Because the rate (3.2%) and the target (95%) are measuring different things in the default setup — a low affected rate versus a high pass-rate target. Set your target to the affected-rate ceiling you want (e.g. 3%) so the gap reads meaningfully.
Affected rate vs first-pass yield — what is the difference? They are complements. If 3.2% of units are affected, first-pass yield is roughly 96.8%. Use affected rate when you want to trend the problem; use yield when reporting the good-build percentage upward.

Last reviewed 2026-05-12.