Tel: +44 (0) 2890 020190
Seatless Butterfly Damper

The IVR model butterfly damper is a seatless butterfly valve intended for low pressure gas and air lines. The narrow wafer body means lightweight construction and this enables ease of fitting in ducts, manifolds, exhaust lines etc. without additional pipe supports or strengthening of pipework.

IVR valves are primarily intended for low pressure large volume gas flow control application. The absence of a seat substantially reduces valve operating torque and so makes the valve very effective for flow control / regulation duties. IVR is an ideal choice for furnace air flow and combustion control applications.

The body is designed for a maximum pressure of 2.5 bar with the maximum shut off pressure being 0.5 bar. The disc is held in position by an axial locking arrangement provided on the top shaft. The shaft sealing is through a stuffing box / gland which is site adjustable.

Conformity to codes and standards:

Actuator mounting bracket ISO 5211 Part II
Valve inspection & testing API 598 / ANSI / FCI: 70-2 (Class II)
Flange standard conformity ANSI 150, DIN PN 6 / 10, BS 10 Table D
Flange standard conformity ANSI 150, DIN PN6 / PN10 / PN16 / PN25, JIS 5K / 10K / 16K, ANSI B16.47 series A & B
WRAS Materials available on request

Technical Specifications

Feature Value
Construction & Type Centric disc, seatless butterfly damper
Body type Narrow wafer single piece
End connection Wafer sandwiched between flanges
Size range 40 NB to 1200 NB
Maximum operating pressure 0.5 bar (max)
Operating temperature range -25C to 180C (Depending on MOC)
Operation Manual or actuated with Pneumatic / Electric actuator
Available material of construction (MOC)
Body/Disc WCB / LCB/ CF8 / CF8M
Shaft AISI 410 / SS 316 SH
Other materials available on request


Tel: +44 (0) 2890 020190
Unit 4, 38-40 Duncrue Crescent
Belfast, BT3 9BW
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