Wafer type butterfly valve with an enclosed worm gearbox and handwheel in place of a lever, rated PN16 on the body of the unit photographed. Gear operation is used on larger sizes and where the valve is throttled or opened against pressure.
Prices on request. Contact us for availability and quotations.
This is the same wafer body as the lever-operated valve, fitted with an enclosed worm gearbox. The worm and wheel reduce the handwheel effort and, being self-locking, hold the disc wherever it is left rather than letting flow forces drive it. The gearbox also carries a position indicator, so the disc angle is readable without tracing the shaft.
Gear operation is not a preference; it becomes necessary as torque rises. Butterfly torque grows with the square of the bore and with differential pressure and velocity, and API 609 requires the operating mechanism to be designed so that the input force needed at the manufacturer's published torque does not exceed 80 lb (360 N). Past that point a lever cannot be used safely, and above roughly 200 mm bore a gearbox is normal.
The body of the unit photographed carries a cast "PN16" mark, the European pressure designation meaning 16 bar maximum at 20 degrees C for a suitable body material. The gearbox is bolted to a machined top pad on the valve neck; ISO 5211 is the standard that fixes those top-flange dimensions (F03, F05, F07, F10 and upward) for part-turn actuator attachment, and the F size on valve and gearbox must match if the operator is ever changed for an electric or pneumatic actuator.
When ordering, state the nominal size, the flange standard the valve will sit between, the pressure rating required, the disc and seat materials, and whether a manual gearbox or a powered actuator is wanted. Confirm the temperature limit and the seat elastomer with the supplier.
| Pressure Rating (unit photographed) | PN16 - 16 bar maximum at 20 °C for a suitable body material |
|---|---|
| Body Style | Wafer (flangeless): clamped between two companion flanges by through bolts. Both flanges must be in place |
| Operator | Enclosed worm gearbox with handwheel and position indicator, bolted to a machined top pad on the valve neck. Self-locking - the disc holds its set position |
| Actuator Mounting | ISO 5211 fixes the top-flange dimensions for attaching part-turn actuators and gearboxes (F03, F05, F07, F10 and upward). The F size on valve and operator must match |
| Operating Force Limit | API 609 requires the operating mechanism to be designed so the input force at the manufacturer's published torque does not exceed 80 lb (360 N) - the reason a gearbox replaces a lever as size and differential pressure rise |
| Closing Direction | Clockwise |
| Face-to-Face | API 609 Category A lug- and wafer-type, metal-to-metal across body flats: 43 mm at NPS 2, 46 mm at NPS 2.1/2 and NPS 3, 52 mm at NPS 4, 56 mm at NPS 5 and 6, 60 mm at NPS 8, 68 mm at NPS 10, 78 mm at NPS 12 and 14, 102 mm at NPS 16, 114 mm at NPS 18, 127 mm at NPS 20, 154 mm at NPS 24, rising to 276 mm at NPS 48. Varies with size - do not quote a single figure |
| Flange Standard (to be specified) | The drilling the valve is designed for must be stated - EN 1092-1 PN10/16 or ASME B16.5 Class 150. The two are separate systems: at DN50 / NPS 2 the EN bolt circle is 125 mm and the ASME bolt circle is 120,7 mm, with M16 bolts against 5/8 in UNC. They are not interchangeable |
| Product Standards (valve type) | MSS SP-67 (flangeless/wafer, single-flange/lug and flanged-end butterfly valves, NPS 1.1/2 - NPS 72); EN 593 (metallic butterfly valves, wafer, lug, flange and butt-welding ends, PN 2,5 - PN 160 and Class 150 - 900, DN 20 - DN 4000); API 609 Category A (manufacturer's rated cold working pressure valves, usually concentric disc and seat, NPS 2 - NPS 48 for ASME Class 125 or 150 bolting patterns) |
