# NL/min — Normal litres per minute

> Source: https://rodlesspneumatic.com/resource-center/pneumatic-glossary/nl-min/
> Language: en-US
> Category: Flow & valves

## Definition

Normal litres per minute: Volumetric flow normalized to a stated reference condition. Normal conditions vary by convention; record the supplier basis. Read the applicable product data and technical standard before treating a catalog value as interchangeable.

## Key facts

- **Term:** NL/min
- **Full form:** Normal litres per minute
- **Selection effect:** Normal conditions vary by convention; record the supplier basis.

## NL/min: definition and engineering context

Normal litres per minute. Volumetric flow normalized to a stated reference condition.

The term belongs to the flow & valves context. Its exact limits can depend on the cited standard, catalog convention, unit system, reference state, and component configuration.

## Why NL/min affects pneumatic selection

Normal conditions vary by convention; record the supplier basis.

- ANR: Keep ANR values tied to the catalog's stated reference definition.
- Qn: Compare only when pressure conditions and measurement conventions match.
- ΔP: Available valve and line flow changes with pressure drop.
- Cv: Do not compare it directly with nominal NL/min without the fluid state and test conditions.

## How to evaluate NL/min in a catalog or replacement project

Read the value together with its unit, test basis, operating pressure, temperature, circuit state, and manufacturer definition.

For replacement work, compare the complete datasheet and drawing. A matching abbreviation or nominal size does not by itself prove functional or dimensional interchangeability.

- Atmosphère Normale de Référence: Reference-air condition used by some pneumatic catalogs for normalized flow.
- Nominal or normalized flow rate: Catalog flow value defined under a stated test condition.
- Pressure drop: Difference between upstream and downstream pressure.
- U.S. flow coefficient: A conventional coefficient describing flow capacity under a defined test basis.

## What to verify before selection

- Normal conditions vary by convention; record the supplier basis.
- Keep ANR values tied to the catalog's stated reference definition.
- Compare only when pressure conditions and measurement conventions match.
- Available valve and line flow changes with pressure drop.

## Common mistakes

- Treating NL/min as a universal definition without checking the manufacturer or standard context
- Mixing gauge and absolute values, incompatible units, or different reference conditions in one comparison
- Selecting a component from the term or nominal value alone without checking the complete operating point and drawing

## Frequently asked questions

### What does NL/min mean in pneumatics?

Normal litres per minute. Volumetric flow normalized to a stated reference condition.

### Why does NL/min matter when selecting a component?

Normal conditions vary by convention; record the supplier basis.

### Can NL/min values be compared directly between catalogs?

Only after the unit, reference condition, test method, operating point, and manufacturer definition have been reconciled.

## Technical references

- [ISO 5598:2020](https://www.iso.org/standard/67985.html): Provides the international fluid-power vocabulary used to interpret pneumatic terminology.
- [ISO 6358-1:2013](https://www.iso.org/standard/56612.html): Defines steady-state flow-rate testing and compressible-flow characteristics for pneumatic components.