The air valve block is the air distribution heart of an air-operated diaphragm pump, directing compressed air alternately to each diaphragm chamber through precision spool and pilot passages. Ningbo Ruican casts the block with the internal airways formed in the wax pattern and then machines the spool bore, port faces and mounting pads in house, which solves the chronic problems of cross-port leakage, stalling and icing that buyers experience with blocks drilled from solid or poorly cored castings.
Specifications
| Parameter | Specification |
|---|---|
| Casting process | Silica sol lost wax investment casting with cast internal air galleries; gravity die casting alternative for high volume aluminium |
| Material options | A356-T6 and ADC12 aluminium; ASTM A351 CF8M and CF8 stainless; ASTM A216 WCB on request |
| Dimensional tolerance (ISO 8062-3 CT grade) | CT5 to CT6 as cast; spool bore held to H7 after honing or reaming; port face flatness within 0.05 mm |
| Machining | CNC milling of port faces and mounting pads, precision boring and honing of the spool bore, drilling and tapping of pilot and exhaust ports |
| Surface finish (Ra) | As-cast Ra 3.2-6.3 um; machined sealing faces Ra 1.6 um; spool bore Ra 0.8-1.6 um after honing |
| Pressure testing | Air leak test at 6 to 10 bar with pressure decay monitoring; cross-port leakage and spool shift function test to customer procedure |
| Weight range | 0.35 kg to 6.5 kg per block |
| Typical lead time | 20 to 30 days for tooling and samples; 25 to 35 days for production after sample approval |
Scope and options
Key features
- Internal air galleries cast to near net shape, so the block needs no long cross-drilled holes and no plugged process holes that can leak later.
- Spool bore honed to H7 with controlled Ra, giving repeatable spool shift and eliminating the stalling that follows from bore taper or scoring.
- Port face flatness held within 0.05 mm, allowing gasket-free or thin-gasket assembly and cutting air loss across the joint.
- Aluminium blocks anodised or hard anodised, and stainless blocks passivated or electropolished, for corrosion resistance in washdown and offshore service.
- Muffler, pilot valve and cycle counter ports cast as bosses and machined to your specified thread form, NPT, BSP or metric.
- Balanced wall design validated by section survey, keeping the block rigid at cycling pressure without excess mass on the pump centre section.
Applications
- Air-operated diaphragm pumps in aluminium for paint, ink, resin and solvent transfer.
- Stainless AODD pumps for food, beverage, cosmetic and pharmaceutical product transfer.
- Moreover, Chemical dosing and transfer pumps handling acids, caustics and slurries.
- Sanitary and hygienic AODD pumps with electropolished stainless air sections.
- Explosion-proof AODD pumps for solvent service in ATEX classified areas.
- Ceramic and mining slurry pumps where the air valve must shrug off abrasive dust and moisture.
Quality & compliance
Inspection and documentation
We produce air valve blocks under IATF 16949 process control, with a control plan covering spool bore diameter, port face flatness and cross-port leakage. Material certification to EN 10204 3.1 is standard, with 3.2 third party witnessed certification available on request, and aluminium heats are supported by spectrographic and mechanical test reports. Every block is air leak tested on a pressure decay rig at the customer’s test pressure, and spool travel is functionally verified before packing. Non-destructive examination, including dye penetrant inspection per ASTM E165 and radiography of critical gallery walls, is performed when specified. Moreover, dimensional reports, PPAP submissions and first article inspection are issued on request. Ningbo Ruican does not claim ATEX, CE or PED certification as a company certificate; conformity to your specified directives is supported by the test evidence we generate to your procedure.
FAQ
Can you cast the internal air passages rather than drilling them?
Yes, most blocks are cast with the galleries formed in the wax pattern, and only short connection holes are drilled. Cast galleries remove the blind cross-holes and plugged ends that commonly leak, and they reduce machining time and cost per part significantly at volume.
What bore finish do you achieve on the spool bore?
We rough bore, then hone or ream the spool bore to H7 with Ra 0.8 to 1.6 um depending on spool and seal design. We record bore roundness and taper on the dimensional report for every sample and on a defined frequency during production.
Do you supply both aluminium and stainless versions?
We cast A356-T6 and ADC12 aluminium for general industrial pumps and CF8M or CF8 stainless for chemical, sanitary and corrosive environments. Both routes share the same port layout and mounting interface, so switching material does not change your pump assembly or your customers’ spare parts strategy. Generally, tell us your market and fluid and we will recommend the alloy and surface treatment.
How do you verify the block will not stall?
We mount each production block on a test rig, pressurised to your operating air pressure, and cycled through spool shift while monitoring pressure decay across the ports. Blocks that show cross-port leakage or delayed shift above your limit are rejected before shipment.
What surface treatments can you apply?
Additionally, aluminium blocks can be clear or coloured anodised, hard anodised for wear resistance, or powder coated. In general, stainless blocks can be passivated per ASTM A967, electropolished, or glass bead blasted. In general, we follow your specified standard and provide treatment records with the shipment.
CTA
Share your AODD pump air valve block drawing or sample, target material and monthly volume, and Ningbo Ruican will return a cast and machined quotation with a tooling plan. Reach Wendy She at sales@cnsandcasting.com or WhatsApp +86-13777124360, or browse more pump and valve work at cnsandcasting.com.
