How do you calculate the refrigerant charge estimate risk score?

Multiply each rating by its weight and sum: severity x 0.40 + occurrence x 0.35 + detection x 0.25. With severity 6, occurrence 4 and detection 3, the score is 2.4 + 1.4 + 0.75 = 4.55.

How is this different from a standard RPN?

A classic FMEA RPN multiplies severity, occurrence and detection, which lets one extreme rating swamp the result. This weighted-sum keeps the score on the same 1-10 scale and deliberately weights severity heaviest (0.40), giving a more stable, comparable ranking across charge failure modes.

Why is severity weighted highest at 0.40?

A refrigerant charge error that destroys a compressor or voids a warranty is far worse than one that is merely common or hard to catch. Weighting severity at 0.40 versus 0.25 for detection forces the score to reflect consequence first, so high-impact charge errors rise to the top of the action list.

What is a good refrigerant charge risk score?

There is no fixed pass mark; scores are for ranking. A 4.55 is mid-range on a 1-10 scale. The practical rule is to set an action threshold for your line, often anything above the top third, and to always act on high-severity items regardless of total score.

How do I lower a charge risk score?

You cannot easily change severity since it is set by consequence, so target occurrence and detection. Calibrated charging scales and locked recipes cut occurrence; weigh-back verification or sealed-system pressure checks cut detection difficulty. Lowering detection from 3 to 1 here would drop the score to 4.05.

What do severity, occurrence and detection mean for charge errors?

Severity is how bad the consequence is, from a slight capacity drop to a field compressor failure. Occurrence is how often the charge error happens, from rare to routine. Detection difficulty is how likely the error escapes your checks, where a high score means it slips through to the customer.

Heat Exchanger, Coil & Radiator Manufacturing calculator

Refrigerant Charge Estimate Calculator

This refrigerant charge estimate risk score is an FMEA-style way to rank how dangerous a charging error is on a condenser, coil or packaged unit before it ships. Getting the refrigerant charge wrong, whether from a bad weigh-in, a calibration drift, or a leak that escaped the test, degrades capacity, trips compressors and triggers warranty claims. Quality and reliability engineers use this weighted score to prioritize which charge-related failure modes deserve poka-yoke, tighter scales, or added verification. By weighting severity highest and detection lowest, it pushes attention toward errors that are both consequential and likely, rather than treating every charge risk equally.

What this calculator does

Score refrigerant charge estimate risk for coils, condensers, evaporators, and thermal modules using severity, occurrence, and detection ratings.
Use it when uncertain internal volume, circuiting, manifold changes, or charge sensitivity could affect HVAC coil or refrigeration equipment launch risk.
It computes a single weighted risk score from charge error severity, occurrence and detection, with weights of 0.40, 0.35 and 0.25 respectively.

Formula used

Refrigerant charge estimate risk score = charge impact severity × 0.40 + charge error occurrence × 0.35 + charge error detection risk × 0.25

Inputs explained

Charge error impact severity:
Charge error occurrence likelihood:
Charge error detection difficulty:

How to use the result

Use it when prioritizing charge-related failure modes in a process FMEA, comparing the risk of competing charging methods, or deciding where to add verification on a charging line.
It is a relative ranking tool, not an absolute safety threshold; scores only mean something when every failure mode is rated on the same agreed scale and rubric.

Current U.S. benchmarks

The producer price index for copper and brass mill shapes stands at 559.593 (BLS, May 2026), up 76.8% from a year earlier. Quotes priced off last quarter's material cost miss this move. Global copper trades at $13,484 per tonne (IMF via FRED, May 2026).

Common questions

How do you calculate the refrigerant charge estimate risk score? Multiply each rating by its weight and sum: severity x 0.40 + occurrence x 0.35 + detection x 0.25. With severity 6, occurrence 4 and detection 3, the score is 2.4 + 1.4 + 0.75 = 4.55.
How is this different from a standard RPN? A classic FMEA RPN multiplies severity, occurrence and detection, which lets one extreme rating swamp the result. This weighted-sum keeps the score on the same 1-10 scale and deliberately weights severity heaviest (0.40), giving a more stable, comparable ranking across charge failure modes.
Why is severity weighted highest at 0.40? A refrigerant charge error that destroys a compressor or voids a warranty is far worse than one that is merely common or hard to catch. Weighting severity at 0.40 versus 0.25 for detection forces the score to reflect consequence first, so high-impact charge errors rise to the top of the action list.
What is a good refrigerant charge risk score? There is no fixed pass mark; scores are for ranking. A 4.55 is mid-range on a 1-10 scale. The practical rule is to set an action threshold for your line, often anything above the top third, and to always act on high-severity items regardless of total score.
How do I lower a charge risk score? You cannot easily change severity since it is set by consequence, so target occurrence and detection. Calibrated charging scales and locked recipes cut occurrence; weigh-back verification or sealed-system pressure checks cut detection difficulty. Lowering detection from 3 to 1 here would drop the score to 4.05.

Last reviewed 2026-05-12.