Disc check valve DN125-200 - 931 | AWS

AWS 931 DN125–DN200 – Spring-Loaded Disc Check Valve

The AWS 931 DN125–DN200 is a wafer-type check valve with a guided disc and return spring, designed for installation between flanges. It is intended to prevent reverse flow in liquid and gas media free of solids. The valve operates automatically via differential pressure; no actuator is used.

Technical Data

• Sizes: DN125, DN150, DN200
• Connection: Wafer between flanges PN6–PN16 or Class 150
• Face-to-face: DIN EN 558, Series 49
• Max pressure: up to 16 bar (pressure derates with temperature)
• Temperature, metallic seat: -20°C to +300°C
• Kv values: 222 m³/h DN125, 288 m³/h DN150, 530 m³/h DN200

Materials and Sealing

Standard Design 9: Body and disc in EN-GJS-400-18-LT, spring cross 1.4408, spring 1.4571. Design 9.1: Disc in 1.4308. Seat options: metal seated, NBR, EPDM, FKM. Metal seat suitable up to +250°C, leakage rate ≥G per EN 12266-1. Soft seats (NBR, EPDM, FKM) provide leakage rate A; temperature limits: NBR +90°C, EPDM +120°C, FKM +200°C.

Applications

Applicable for heating, cooling, HVAC, process water, general industrial piping, air, and compatible gases. Not recommended for fluids with solids, sludge, or deposits, as these affect disc movement and seat sealing.

Installation

Flow direction must match the arrow on the body. Clean piping and correct centering between flanges are required. Avoid installation immediately downstream of pumps or fittings causing turbulence. Pressure drop data is based on water at 20°C in horizontal installation.

FAQ

How does this differ from AWS 931 DN15–DN100?
Larger sizes use EN-GJS-400-18-LT body and have different Kv values and opening pressures.

Can it be used without a spring?
Only in suitable vertical upward flow. Spring is required for horizontal installation.