---
title: "Turning vane (ESP inlet)"
description: "Turning vanes are gas-distribution devices installed in the inlet plenum of an ESP — and sometimes in upstream duct elbows — to straighten and evenly distribute the flue gas before it enters the plate stack. Even gas distribution is critical to ESP performance: a poorly distributed flow leaves part of the collecting area under-used while overloading the rest."
canonical_url: "https://sylio.co/glossary/turning-vane-esp-inlet"
last_updated: "2026-06-28T02:29:31.530Z"
---

**Turning vanes** are gas-distribution devices installed in the inlet plenum of an [ESP](/glossary/electrostatic-precipitator) — and sometimes in upstream duct elbows — to straighten and evenly distribute the flue gas before it enters the plate stack. Even gas distribution is critical to ESP performance: a poorly distributed flow leaves part of the [collecting area](/glossary/specific-collection-area) under-used while overloading the rest.

## Failure modes

- **Vane fouling** — ash builds up on the leading edge and disrupts the designed flow pattern
- **Vane erosion** — abrasive ash gradually thins the vane, especially on biomass and waste-to-energy duty
- **Distortion** — thermal cycling warps the vane and changes the deflection angle
- **Detachment** — vanes loosen and fall into the gas stream, blocking field inlets

## Sonic horns on inlet ducting

Acoustic horns installed in the inlet plenum keep turning-vane surfaces and adjacent ducting walls clean, preserving the designed distribution. Without periodic cleaning, distribution drift can reduce overall ESP [collection efficiency](/glossary/collection-efficiency) by several percentage points before the cause is identified.

## Related terms

- [Electrostatic precipitator](/glossary/electrostatic-precipitator)
- [Sneakage](/glossary/sneakage)
- [Collection efficiency](/glossary/collection-efficiency)