# Meter-in — Supply-flow control

> Source: https://rodlesspneumatic.com/resource-center/pneumatic-glossary/meter-in/
> Language: en-US
> Category: Valves & circuits

## Definition

Supply-flow control: Restricts air entering an actuator. Use selectively because overrunning loads can become unstable. Read the applicable product data and technical standard before treating a catalog value as interchangeable.

## Key facts

- **Term:** Meter-in
- **Full form:** Supply-flow control
- **Selection effect:** Use selectively because overrunning loads can become unstable.

## Meter-in: definition and engineering context

Supply-flow control. Restricts air entering an actuator.

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

## Why Meter-in affects pneumatic selection

Use selectively because overrunning loads can become unstable.

- Manifold: Confirm station pitch, electrical architecture, total flow, and expansion limits.
- Silencer: Backpressure can reduce cylinder speed and valve performance.
- 3/2 valve: Common for single-acting actuators and on/off air functions.
- 5/2 valve: Common for double-acting cylinders.

## How to evaluate Meter-in 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.

- Common valve or distribution base: Base that shares supply and exhaust or distributes ports among multiple stations.
- Pneumatic exhaust muffler: Porous or baffled element used to reduce exhaust noise.
- Three-port, two-position valve: Directional valve with three ports and two switching states.
- Five-port, two-position valve: Directional valve with pressure, two working, and two exhaust ports.

## What to verify before selection

- Use selectively because overrunning loads can become unstable.
- Confirm station pitch, electrical architecture, total flow, and expansion limits.
- Backpressure can reduce cylinder speed and valve performance.
- Common for single-acting actuators and on/off air functions.

## Common mistakes

- Treating Meter-in 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 Meter-in mean in pneumatics?

Supply-flow control. Restricts air entering an actuator.

### Why does Meter-in matter when selecting a component?

Use selectively because overrunning loads can become unstable.

### Can Meter-in 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 1219-1:2012](https://www.iso.org/standard/60184.html): Defines graphical symbols and circuit-documentation principles for fluid-power systems.