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🔷 Wafer Type Non-Return Valve (NRV)

A wafer type non-return valve is a compact valve installed between two pipe flanges to allow one-way flow only and prevent backflow. It is widely used in water supply, HVAC, chemical plants, oil & gas, and pumping systems.

It is called “wafer type” because it is thin like a wafer and is sandwiched between flanges, saving space and weight.

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🔶 Types of Wafer Type Non-Return Valves

1. Single Plate Wafer Check Valve

✔ Description

• One circular disc hinged at one side

• Opens with forward flow pressure

• Closes when flow stops or reverses

🔧 Technical Details

• Size range: DN 25 to DN 600

• Pressure rating: PN10 / PN16

• Body materials: Cast Iron, Ductile Iron, Stainless Steel

• Seat: Rubber (EPDM / NBR) or PTFE

• Installation: Horizontal or vertical (flow upward preferred)

📌 Applications

• Water pumps

• HVAC systems

• Low-pressure industrial pipelines

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2. Dual Plate Wafer Check Valve (Most Used Type)

✔ Description

• Two semi-circular plates with spring assistance

• Opens with forward flow, closes quickly when flow stops

• Designed to reduce water hammer (“non-slam” type)

🔧 Technical Details

• Size range: DN 50 to DN 1200

• Pressure class: PN16 to Class 150/300 (higher variants available)

• Body: Carbon steel, ductile iron, stainless steel

• Seat: EPDM, NBR, Viton

• Design: Compact, low-pressure loss

📌 Applications

• Pump discharge lines

• Power plants

• Oil, gas, and chemical pipelines

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3. Spring Loaded Wafer Check Valve

✔ Description

• Uses a spring to assist closing

• Provides fast and controlled shut-off

• Prevents reverse surge effectively

🔧 Technical Details

• Pressure: Low to medium (varies by material)

• Body: Stainless steel / plastic / alloy steel

• Seal: EPDM / FPM / PTFE

• Response: Very fast closure

📌 Applications

• Chemical processing

• Slurry and wastewater systems

• Corrosive fluid pipelines

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4. Ball Type Wafer Check Valve

✔ Description

• Uses a free-floating rubber or metal ball

• Ball lifts during forward flow

• Seals backflow by blocking the seat

🔧 Technical Details

• Size: DN 40 to DN 400+

• Pressure: PN10 / PN16 typical

• Body: Cast iron / ductile iron

• Ball: Rubber-coated or solid metal

📌 Applications

• Sewage systems

• Wastewater treatment plants

• Sludge and dirty fluid pipelines

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🔷 Common Technical Specifications

Parameter	Typical Range
Size	DN 25 to DN 1200
Pressure rating	PN10 / PN16 / Class 150–300
Body materials	CI, DI, CS, SS304, SS316
Seat materials	EPDM, NBR, Viton, PTFE
Installation	Sandwiched between flanges
Flow type	One-direction only
Maintenance	Low

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🔶 Key Features

• Compact and lightweight design

• Prevents reverse flow automatically

• Low pressure drop

• Easy installation between flanges

• Suitable for vertical and horizontal pipelines

• Low maintenance operation

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💰 Approximate Price Range (India)

Type	Small (1–2 inch)	Medium (4–8 inch)	Large (10+ inch)
Cast Iron Wafer NRV	₹800 – ₹2,500	₹2,500 – ₹8,000	₹10,000 – ₹40,000
Stainless Steel NRV	₹3,000 – ₹10,000	₹10,000 – ₹35,000	₹40,000 – ₹1,50,000
High-pressure variants	₹10,000+	₹30,000+	₹1,00,000+

(Prices vary depending on brand, size, and pressure class.)

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🧠 Summary

Wafer type non-return valves are compact, cost-effective, and efficient backflow prevention devices. Among all types, the dual plate wafer check valve is the most widely used due to its non-slam and low-pressure loss performance.

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