Threaded Double Sphere Bellow

Product Overview

The Threaded Double Sphere Bellow is a high-performance flexible connector engineered to absorb vibration, reduce noise, and compensate for pipe misalignment in pressurised piping systems. Its distinctive dual-arch rubber body provides superior flexibility compared to single-sphere designs, making it the preferred choice for demanding pump discharge and HVAC installations.

Construction & Materials

The bellow body is moulded from premium-grade EPDM or NBR rubber, selected to suit the specific fluid and temperature requirements of the application. EPDM compound is recommended for water-based systems, steam, and outdoor HVAC installations due to its excellent resistance to weathering, ozone, and heat. NBR compound is the preferred choice for oil-containing media and fuel-adjacent services.

The double-arch design incorporates two convolutions within the rubber body, distributing stress evenly and significantly increasing the range of axial compression, axial extension, and lateral deflection that the connector can accommodate. Internal fabric reinforcement layers maintain structural integrity under working pressure while preserving the inherent flexibility of the rubber.

Connection Types

Both ends of the bellow are fitted with male-threaded steel nipples available in BSP (British Standard Pipe) or NPT (National Pipe Taper) thread forms. This threaded configuration allows direct installation into standard female-threaded fittings, valves, and pump ports without the need for flanges or additional adapters, simplifying installation and reducing overall system cost.

Size Range & Pressure Rating

The Threaded Double Sphere Bellow is available in nominal pipe sizes from 3/4" through to 4", covering the most common small-bore and medium-bore piping requirements. The rated working pressure is 10 bar (145 psi), suitable for the majority of building services, HVAC, and light industrial pump applications.

Movement Capabilities

The double-arch geometry enables the connector to absorb movement in multiple planes simultaneously:

• Axial compression and extension: accommodates thermal growth and pump thrust along the pipe centreline.
• Lateral deflection: compensates for parallel offset between connected pipe ends caused by installation tolerances or structural movement.
• Angular deflection: absorbs minor angular misalignment between pipe centrelines.

Typical Applications

The Threaded Double Sphere Bellow is widely used across building services and light industrial sectors, including:

• Pump discharge and suction lines — isolates pump vibration from the distribution network, protecting pipework and fittings.
• HVAC chilled water and heating circuits — reduces structure-borne noise transmission through pipework.
• Compressor connections — absorbs pulsation and vibration generated by reciprocating or rotary compressors.
• General industrial piping — anywhere flexible pipe connections are required to accommodate movement or misalignment.