A raised-seat diaphragm valve body that shortens diaphragm travel for longer service life and finer throttling control — the standard geometry for most diaphragm valve applications.
Ningbo Baodi Plastic Valve Co., Ltd. traces its origins back to 1979, with its predecessors being Zhenhai Chemical Valve Factory and Beilun Plastic Valve Factory. The company is one of the earliest Weir Type Plastic Diaphragm Valves Manufacturers and Custom Weir Type Plastic Diaphragm Valves Factory in China to design and produce industrial plastic valves and receive acceptance from the Ministry of Chemical Industry. In 1979, the company manufactured its first plastic diaphragm valve, which passed the technical appraisal of the Ministry of Chemical Industry in 1983. In 1992, the company invented the one-piece flange ball valve, a structural design that has since become the most widely used plastic valve product in chemical-related industries. The development history of the company and its predecessors also represents an important chapter in the application of plastic valves in China's industrial production.
In 2006, the company expanded its product line to cover industrial plastic pipes and fittings, becoming one of the first domestic enterprises to apply CPVC material in the production of industrial-grade piping valves. Over more than 40 years since its establishment, the company has designed and manufactured various plastic valves for the most demanding industries. It has served tens of thousands of enterprises both domestically and internationally, exporting to more than 60 countries, and has consistently remained a leading manufacturer of industrial thermoplastic valves and piping systems. Our professional service and stable quality have always been well received and recognized by customers.
Baodi ranks among the global leaders in the number of product categories, capable of fully covering industrial plastic pipe and valve requirements. The company has obtained ISO 9001, ISO 14001, and ISO 45001 system certifications, as well as the national special equipment pressure piping component manufacturing license. It is recognized as a National High-Tech Enterprise and a Ningbo City Specialized and Sophisticated Enterprise. Baodi is a principal drafter of the national standard for plastic diaphragm valves and the chemical industry standards for plastic diaphragm valves, plastic ball valves, and plastic check valves.
Design Idea
2D Drawing
3D Modeling
Mold Fabrication
Prototype Testing
Full-scale production
Weir type plastic diaphragm valves use a raised internal seat, or weir, molded into the flow path so the diaphragm only needs to travel a short distance to make contact and seal — unlike a straight-through diaphragm valve, where the diaphragm must stretch across the full pipe bore. This shorter stroke reduces diaphragm stress and wear per cycle, generally extending diaphragm service life and giving finer control over throttling position for a given handwheel or actuator travel.
Because the weir raises the valve's minimum flow restriction slightly compared with a straight-through design, it is the default diaphragm valve geometry for the great majority of general and chemical process applications, reserving the straight-through variant for lines that specifically need an unrestricted, full-bore flow path — such as handling very heavy slurries or requiring pigging. PVC-U, CPVC, or PP body options and a selectable diaphragm elastomer keep the weir-type design chemically flexible across process fluids.
The weir shape suits the majority of general and chemical process duty, offering longer diaphragm life and finer throttling than a straight-through design.
Body material determines chemical compatibility and temperature range; the weir geometry is available across all standard material options.
| Material | Temperature Range | Typical Strengths | Common Use |
| PVC-U | 0°C to 60°C | Broad acid and alkali resistance, economical | General water treatment and utility isolation |
| CPVC | 0°C to 95°C | Higher temperature ceiling than PVC-U with similar chemical resistance | Hot process water, elevated-temperature chemical lines |
| PP | 0°C to 90°C | Good solvent resistance, lighter than PVC-U | General chemical processing and dosing |
| Item | Description |
| Valve Type | Weir-type diaphragm valve |
| Body Material | PVC-U, CPVC, or PP |
| Diaphragm Material | EPDM, FPM (Viton), or PTFE-faced EPDM |
| Bonnet Material | Matched to body or glass-reinforced polypropylene |
| Size Range | DN15 – DN150 (1/2 inch – 6 inch) |
| End Connection | Socket, threaded, or flanged |
| Working Pressure | Up to 150 psi (10 bar) at 20°C, rating decreases with temperature |
| Working Temperature | 0°C to 95°C, material dependent |
| Sealing Performance | Bubble-tight shutoff, suitable for throttling duty |
| Operation | Handwheel standard; actuator mounting available |
| Flow Path | Raised weir seat, reduced diaphragm travel versus straight-through design |
Both use a flexible diaphragm; the body geometry changes flow restriction, diaphragm life, and throttling behavior.
| Factor | Weir Type Valve | Straight-Through Valve |
| Diaphragm Travel | Short — diaphragm only reaches down to the raised weir | Long — diaphragm must span the full pipe bore |
| Diaphragm Wear | Lower per-cycle stress, generally longer service life | Higher per-cycle stress on the diaphragm |
| Flow Restriction | Slightly reduced flow area at the weir | Full, unrestricted bore when open |
| Throttling Precision | Finer control for a given travel distance | Coarser control over the same travel distance |
| Best Use | General and chemical process duty, most applications | Heavy slurries or lines requiring a full-bore, pigging-compatible path |
| Availability | Standard, most common diaphragm valve configuration | Available on request for specific full-bore requirements |
A raised weir seat shortens the distance the diaphragm must travel to make contact and seal.
Weir seat dimensions and diaphragm seating are checked closely, since the shortened travel depends on accurate weir geometry.
The shortened weir-type stroke suits compact actuators as well as handwheel operation.
| Operation Type | Best Suited For | Key Characteristics |
| Handwheel | Local throttling and shutoff on general process lines | Lowest cost, fine control over the short weir stroke |
| Pneumatic Actuator | Automated process lines with compressed air available | Compact actuator sizing benefits from the shortened stroke |
| Electric Actuator | Remote-controlled or monitored process valves | Integrates with control systems and remote monitoring |
Payment: T/T (bank transfer), L/C, and PayPal are accepted, with flexible terms for repeat orders. A deposit is typically required to confirm production.
Shipping: Sea freight (FCL/LCL) for large-volume orders, air freight for time-sensitive shipments, and express courier for samples. Valves are packed in cartons or wooden crates depending on size.
Delivery: Shipment from the nearest available port or airport, with door-to-door, FOB, CIF, or EXW terms on request.
Each valve is covered under a standard warranty against manufacturing defects in material and workmanship, generally valid for 12 months from the shipment date.
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Share your process fluid, sizing, and flow control requirements, and get a material recommendation for your line.
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Contact
baodivalve@bdsjfm.com
+86-574-86817753
+86-574-86812190
After-Hours Hotline：
+86-18395898313
NO.42 Yongjiang Road, Beilun,Ningbo city, Zhejiang province,P.R.China
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