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Series Features
Key Features of the BD Series Quarter Turn Gear Box
- Ductile Iron Construction — Precision-cast ductile iron body resists mechanical impact and corrosion, maintaining dimensional stability across pressure cycling and thermal variation.
- Tapered Roller Bearings — Bearings at primary drive points reduce axial and radial load friction, enabling smooth handwheel operation even at elevated torque ranges.
- Self-Locking Worm Gear — The worm gear geometry prevents back-drive under actuator load, eliminating the need for external locking mechanisms or brake assemblies.
- Interchangeable Bottom Flanges — The bottom flange is independently replaceable, allowing the gear box to be adapted to different valve mounting faces without replacing the entire actuator unit.
- Stem Bush Compatibility — Available stem bush inserts provide direct keyed or threaded engagement with a wide variety of valve stem profiles, reducing adaptor hardware and assembly clearance issues.
Environmental and Ingress Protection Ratings
- Standard IP67 Rating — The gear box housing is sealed to IP67 as standard, permitting temporary immersion in water up to 1 metre for 30 minutes without ingress to internal components.
- Optional IP68 Rating — For continuous submersion applications such as subsea pipelines or flood-prone valve pits, IP68 sealing is available as a factory-configured option.
- Wide Ambient Temperature Range — Rated for operation from -20°C to 120°C, suitable for outdoor installations in cold climates as well as high-temperature process pipework.
- Sealed Lubricant Chamber — Internal grease cavity is sealed against moisture and particulate ingress, reducing maintenance intervals in outdoor or high-humidity service.
Motorization and Actuator Integration
- Electric Actuator Ready — Output flange geometry and drive coupling are compatible with standard IEC-frame electric actuators, enabling automated control integration without custom adaptor machining.
- Manual Override Capability — Handwheel input can be retained alongside an electric actuator drive, providing manual fallback during power outages or actuator maintenance.
- Torque Output Scalability — The BD Series spans a range of gear ratios and output torques, allowing selection of the correct unit for small instrument valves through to large-diameter pipeline isolation valves.
- Consistent Position Indication — Open and closed position indicators are integrated into the gear box body, providing visual confirmation of valve status without auxiliary switches.
Quarter Turn Gear Box Type Comparison
| Parameter | Worm Gear Box (BD Series) | Bevel Gear Box | Spur Gear Box |
|---|---|---|---|
| Back-drive prevention | Self-locking (inherent) | Requires brake or lock | Requires brake or lock |
| Typical efficiency | 30–60% | 90–95% | 85–92% |
| High-torque output | Yes, compact envelope | Moderate | Moderate |
| Noise level | Low | Low to moderate | Moderate |
| Motorization compatibility | Electric, pneumatic | Electric | Electric |
| Ingress protection (BD) | IP67 standard / IP68 option | Varies by model | Varies by model |
| Typical application | Ball, butterfly, plug valves | Gate, globe valves | Light-duty quarter-turn |
Frequently Asked Questions — BD Series Quarter Turn Gear Box
Q1: What does the self-locking feature of a worm gear box mean in practice?
In a worm gear arrangement, the lead angle of the worm is low enough that reverse torque applied to the output shaft cannot rotate the worm back through the gear. This means the valve remains in its last set position — open or closed — without requiring a separate mechanical lock, spring-return, or brake on the actuator. It is particularly relevant for fail-in-place valve duty and for manual handwheel installations where the operator cannot be present to maintain force on the handwheel.
Q2: What is the difference between IP67 and IP68, and which should I specify?
IP67 certifies the enclosure against temporary submersion — typically defined as immersion up to 1 metre depth for up to 30 minutes. IP68 covers continuous or prolonged submersion at greater depths, with the specific rating confirmed between the manufacturer and the end user. For valve pits that drain completely between access events, IP67 is typically sufficient. For tidal or permanently flooded installations, IP68 should be specified and the depth and duration of submersion should be confirmed at the time of order.
Q3: How does the interchangeable bottom flange work, and which valve flanges are supported?
The bottom flange of the BD Series is a separately bolted component that interfaces with the valve mounting pad. By supplying flanges in multiple ISO 5211 sizes (F05 through F16 and beyond), the same gear box body can be mounted to different valve topworks without modification. When replacing an existing actuator, the correct bottom flange size is selected to match the valve's ISO 5211 interface, and the stem bush is selected to match the stem drive profile. This reduces the number of gear box variants needed across a valve fleet.
Q4: Can the BD Series gear box be used with an electric actuator, and are there torque limitations?
Yes. The gear box output and top flange are designed for compatibility with standard IEC-frame electric actuators. The upper drive coupling accepts the actuator output shaft directly, and the top flange bolt pattern follows ISO 5211 conventions. When selecting an actuator, the actuator output torque must not exceed the maximum input torque rated for the specific BD Series model, as the gear box internal components are sized to a defined torque envelope. The gear ratio also affects actuator cycle time — higher ratios give greater torque multiplication but slower travel speed.
Q5: What maintenance does the BD Series require in continuous outdoor service?
Under normal operating conditions, the sealed grease-filled housing requires no routine lubrication during the design service life. Periodic inspection should include checking the integrity of the shaft seal at the handwheel input and output stem bush for signs of grease weeping or moisture ingress, verifying the condition of the cover gasket, and confirming that the position indicator reads correctly against the valve's physical position. In high-cycle motorized service, bearing condition should be assessed during scheduled plant shutdowns. No special tooling is required for flange or stem bush replacement in the field.
Q6: What temperature range is the BD Series rated for, and does this affect lubricant selection?
The BD Series is rated for ambient temperatures from -20°C to 120°C as a standard configuration. Within this range, the factory-supplied grease maintains adequate film thickness and does not harden to a point that impedes bearing or gear movement. For installations approaching the lower end of this range in cold-climate outdoor environments, startup torque may be slightly elevated until operating temperature is reached — this should be accounted for in actuator sizing. Applications outside this temperature range, such as cryogenic or high-temperature steam service, require consultation with the supplier to confirm seal and lubricant compatibility.
