Volute Casing for Centrifugal Pumps | Specifications & Selection

Product Specifications

Technical details and manufacturing context for Volute Casing

Definition

A volute casing is the stationary outer housing of a centrifugal circulation pump. Its primary function is to collect the fluid discharged from the rotating impeller, guide it through an expanding cross-sectional area (the volute), and efficiently convert the high-velocity kinetic energy of the fluid into usable pressure energy for the system. It is a critical component for determining pump efficiency and head characteristics. The casing is typically manufactured from cast iron, stainless steel, bronze, or engineering plastics, with material grades such as HT250, QT450, 304, or 316, selected based on corrosion and strength requirements. Key parameters include nominal diameter (DN50–DN300, matching pump flanges per ISO 7005), flow rate (10–500 m³/h), head (20–120 m), operating pressure (1.0–1.6 MPa), operating temperature (-20 to 120 °C), wall thickness (5–20 mm), surface roughness (Ra 3.2–6.3 µm per ISO 1302), dimensional tolerance (±0.5 mm per ISO 2768-m), weight (15–150 kg), hydraulic test pressure (1.5× rated), and efficiency (75–90% per ISO 9906). These values are reference ranges and must be confirmed for the specific model and application. The volute casing interfaces with the impeller, pump flanges, and discharge nozzle; proper fit is ensured by dimensional tolerances. Verification questions include checking material grade, pressure rating, and surface finish against the intended duty. Maintenance signals include erosion, corrosion, or cracking, which may reduce efficiency or cause leakage. Failure boundaries include exceeding pressure or temperature limits, which can cause material degradation or permanent deformation. Always verify model-specific values and standards with the legal manufacturer or supplier.

Working Principle

Fluid enters the casing tangentially from the impeller outlet at high velocity. As the fluid travels through the gradually expanding spiral passage of the volute, its velocity decreases according to the principle of conservation of mass (continuity). This reduction in velocity results in a corresponding increase in static pressure, as described by Bernoulli's principle, thereby converting kinetic energy to pressure energy before the fluid exits through the discharge nozzle.

Common Materials

Cast Iron, Stainless Steel, Bronze, Engineering Plastics

Technical Parameters

Parameter	Typical range	Notes & selection driver
Nominal Diameter	DN50–DN300 mm	Matches pump inlet/outlet flange size.ISO 7005
Flow Rate	10–500 m³/h	Determines pump size and efficiency.
Head	20–120 m	Pressure generated by the pump.
Operating Pressure	1.0–1.6 MPa
Operating Temperature	-20–120 °C	Exceeding limits may cause material degradation.
Material Grade	HT250, QT450, 304, 316	Select for corrosion and strength requirements.GB/T 1348, ASTM A48
Wall Thickness	5–20 mm	Thicker for higher pressure ratings.
Surface Roughness	Ra 3.2–6.3 µm	Smoother reduces hydraulic losses.ISO 1302
Dimensional Tolerance	±0.5 mm	Ensures proper fit with impeller and flanges.ISO 2768-m
Weight	15–150 kg	Affects handling and installation.
Hydraulic Test Pressure	1.5× rated MPa	Verifies integrity without permanent deformation.
Efficiency	75–90 %	Higher reduces energy cost.ISO 9906

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Components / BOM

Casing Body Part
Forms the main spiral-shaped pressure chamber that converts velocity to pressure.

Material: Cast Iron/Stainless Steel
Discharge Nozzle (Flange) Part
Provides the connection point for the pressurized fluid to exit the pump and enter the system piping.

Material: Same as Casing Body
Suction Nozzle (Flange) Part
Provides the connection point for fluid to enter the casing from the impeller.

Material: Same as Casing Body
Wear Ring / Casing Ring Part
A replaceable ring fitted to the casing to minimize internal recirculation leakage and protect the casing from wear at the impeller interface.

Material: Bronze/Stainless Steel

Applied To / Applications

This component is essential for the following industrial systems and equipment:

Circulation Pump

View system integration details

Manufacturers of Volute Casing

Manufacturer profiles associated with Volute Casing.

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Frequently Asked Questions

What is the primary function of a volute casing?

The volute casing collects fluid from the impeller and converts its kinetic energy into pressure energy through an expanding spiral passage, increasing static pressure before discharge.

Which materials are commonly used for volute casings?

Common materials include cast iron, stainless steel, bronze, and engineering plastics. Material grades such as HT250, QT450, 304, and 316 are selected based on corrosion and strength needs.

What parameters should be verified when selecting a volute casing?

Key parameters include nominal diameter, flow rate, head, operating pressure, temperature, wall thickness, surface roughness, dimensional tolerance, weight, and efficiency. Always confirm these with the manufacturer for your specific application.

How does the volute casing affect pump efficiency?

The casing's geometry and surface finish influence hydraulic losses. A smoother surface (lower Ra) reduces friction, while proper volute design ensures efficient kinetic-to-pressure energy conversion, affecting overall efficiency.

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records.

Preliminary Technical Classification

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pressure:	Up to 25 bar (standard designs), higher with reinforced construction
flow rate:	5-5000 m³/h (varies by pump size and design)
temperature:	-20°C to 150°C (depending on material)
slurry concentration:	Up to 40% solids by weight (for abrasion-resistant materials)

Volute Casing

Product Specifications

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