The XNFM PZD series uses an inflatable rubber seat that expands toward the disc only at closure — giving near-zero friction during operation, dramatically longer service life and far less torque than a conventional butterfly valve.

An inflatable seated butterfly valve (also called an inflatable sealing butterfly valve or expansion-seat butterfly valve) is a soft-seal butterfly valve whose elastomer seat is inflated by compressed air only at the moment of closure. The seat expands toward the disc and presses evenly around its circumference, producing a tight, uniform seal. When the valve opens, the seat deflates and retracts, releasing the disc completely.

This is the key difference from a conventional butterfly valve: in a normal design, the disc sweeps and scrapes against the seat during every stroke, generating hard friction that wears both components. On the XNFM PZD inflatable seated butterfly valve, the disc and seat only touch for an instant, so the disc experiences virtually no impact or abrasion during opening and closing.

The PZD valve uses gas pressure to inflate a special rubber seat that extends toward the disc. When the solenoid or pilot valve sends compressed air into the seat cavity, the rubber expands uniformly around the disc circumference, pressing against it with even pressure distribution. The result is a tight, dust-tight seal with no localised stress points.

During opening and closing, the disc and the seat are only in instantaneous contact, so the disc is subjected only to slight impact. By contrast, the hard friction generated when a conventional butterfly valve disc brushes against its seat steadily reduces both valve performance and service life.

Because the seat does the sealing rather than the disc scraping, the PZD requires very little torque to open and close — which makes both the actuator and the valve last considerably longer.

Figure 2. XNFM PZD inflatable seated butterfly valve — pneumatic actuator with solenoid, pressure regulator and inflatable seat.

The PZD series is offered in several material combinations so the same platform covers general industry through aggressive and abrasive duties:

Temperature and torque are application-dependent. Temperature range varies with actual application and manufacturing materials; operating torque varies with the working condition. Seat sealing pressure up to 8 bar.

Full dimensional range for the PZD Series Inflatable Sealing Butterfly Valve. Torque values are the recommended minimum and maximum for actuator sizing (Nm).

All dimensions in mm unless stated. Temperature limits: −40 °C to +170 °C depending on material and application. Supply air pressure for seat sealing up to 8.0 bar. Operating torque subject to actual application.

Figure 3. XNFM PZD series inflatable sealing butterfly valve — dimension drawing, material options and complete size table, 2" to 24".

In a conventional soft-seated butterfly valve, the disc rubs against the seat through the whole stroke. That friction must be overcome by the actuator at every cycle, so the actuator must be larger, consume more air, and work harder against wear. Over thousands of cycles, the seat deforms, the disc surface scores, and sealing performance drops.

Because the PZD seat is deflated during opening and closing, the disc swings freely. The result is lower operating torque, smaller actuators, cleaner media paths and dramatically longer valve life — even in abrasive powder service.

The PZD inflatable seated butterfly valve is designed for demanding powder, granule and slurry duties. Proven application media include:

For dry solids, gases and mud, an inflatable seated butterfly valve is generally the better choice over a standard soft-seated butterfly valve — the inflatable seat keeps the seal tight even when the media is abrasive.

The PZD series is designed for demanding conditions, and a complete range of pneumatic actuators, limit switches and control accessories is available to meet different plant requirements. The actuator package can be configured for on/off, modulating or smart control duties — talk to the XNFM team about your control philosophy.

When selecting a PZD inflatable seated butterfly valve, specify the nominal diameter, body material (cast iron / SS / aluminum), disc material (cast iron / SS 304 / SS 316), seat material (EPDM or NBR), the working pressure and temperature, and the actuator requirement. XNFM provides processing customization and engineering support for OEM and end-user projects.