The rotary airlock valve body is the cylindrical housing that holds the vaned rotor and meters grain from a vacuum conveying line into a trailer while maintaining the air seal. It mounts beneath the cyclone or receiving hopper on pneumatic grain vacuums and self-unloading grain trailers, cycling at high throughput. Buyers face rotor tip wear from poor bore geometry, air leakage that collapses system vacuum, and cracking at the inlet and outlet flanges. We cast a uniform wall section, then machine the rotor bore and flange faces.
Specifications
| Casting process | Material options | Dimensional tolerance (ISO 8062-3 CT grade) | Machining | Surface finish (Ra) | Weight range | Typical lead time |
|---|---|---|---|---|---|---|
| Silica sol investment casting (lost wax), stress relieved before machining | 304 and 316 stainless steel, ductile iron QT500-7, gray iron HT250, aluminium A356, hardfaced options | CT6–CT7 as cast; CT5 on rotor bore and end face datums | CNC horizontal boring, end face milling, flange drilling and tapping, bore finish turning | Ra 3.2 µm as cast, Ra 1.6 µm on machined faces, Ra 0.8 µm on rotor bore and end faces | 9 kg – 42 kg | Tooling 26–34 days, samples 17–21 days, production 33–43 days |
Scope and options
Key features
- Moreover, Precision rotor bore machined for consistent vane tip clearance and minimal air leakage.
- Inlet and outlet flange faces milled flat to protect the vacuum seal under continuous cycling.
- Uniform wall section design prevents distortion during machining and in service.
- Replaceable wear liner or hardfaced bore option for abrasive grain duty and extended service life.
- Stainless or ductile iron options to suit food-grade, fertiliser or general grain handling requirements.
- End faces machined square to the bore axis so end plates seal without shimming.
Applications
- Pneumatic grain vacuums and grain vacuum transfer units
- Self-unloading pneumatic grain trailers
- Cyclone discharge and receiving hoppers on grain handling systems
- Seed treatment and cleaning line discharge valves
- Feed mill and grain storage transfer points
Images
Quality & compliance
Each valve body ships with EN 10204 3.1 material certification and a dimensional report covering rotor bore diameter and cylindricity, end face squareness, flange flatness and bolt circle position. Moreover, we can perform air leakage testing or dimensional verification against your rotor assembly on request. Our IATF 16949 certified quality system covers melt control, stress relieving with recorded furnace charts, and in-process inspection at every machining stage. PPAP Level 3 and First Article Inspection packages are available for new program launches, with capability data retained on the rotor bore.
FAQ
How do you control rotor tip clearance?
We finish-bore the housing to CT5 and hold cylindricity and end face squareness within your drawing limits, then verify the bore against the bore axis. Send us your rotor diameter and target clearance and we will set the machining band to protect that clearance across the operating temperature range.
Can you supply the valve body with a replaceable wear liner?
Yes. For abrasive duty we can machine the body to accept a bolted or pressed wear liner, or apply a hardfaced layer to the bore sweep area. Both approaches extend service life substantially and let you refresh the clearance without replacing the whole body.
Which material is best for food-grade or seed handling?
304 stainless is the standard choice where grain or seed contacts food or planting supply chains, since it cleans easily and resists corrosion from fertiliser dust. For general grain handling where cost is the priority, ductile iron QT500-7 with a suitable internal coating performs well.
Do you machine the inlet and outlet flanges to our pattern?
Yes. We mill both flange faces flat and drill the bolt circles to your drawing, holding positional tolerance to the grade you specify. Counterbores, dowel holes, sight glasses and access ports can all be incorporated into the machining program before shipment.
Can you accommodate large diameter airlock bodies?
Generally, we currently produce bodies up to roughly 500 mm bore diameter and 42 kg in weight. If your design is larger, send the drawing and we will review feasibility against our flask and shell capabilities and advise whether a segmental or split design is more practical.
CTA
Send your airlock valve body drawing, rotor specification and annual volume and Ningbo Ruican will return a quotation, material recommendation and tooling plan within three working days. Contact Wendy She at sales@cnsandcasting.com, WhatsApp +86-13777124360. More details on cnsandcasting.com.
