Hy-Check Valve - 181M-EP | Cla-Val

Cla-Val 181M-EP Hydraulic Check Valve for Seawater Service

The Cla-Val 181M-EP is a Hy-Check Valve for seawater, engineered for marine AFFF systems where backflow prevention is required during foam solution deployment. Product documentation specifies it as a seawater service valve for AFFF applications, compliant with MIL-F-20042 standards.

Operating Principle

The Hy-Check design integrates a hydraulically operated diaphragm valve with an internal check feature. Under normal flow, the valve remains open; if flow ceases or backpressure develops, the internal check closes to prevent reverse flow to the upstream line. Cla-Val technical literature describes this as a hydraulically actuated diaphragm valve with built-in check function to prevent return flow.

Materials and EP Compatibility

The EP suffix indicates ethylene propylene elastomers, critical for compatibility with seawater and aqueous firefighting systems. In Cla-Val’s marine quick reference guide, the 181M-EP is listed as Hy-Check Valve (Sea Water), while the 181PM-EP is differentiated as a Power Hy-Check Valve for AFFF concentrate service.

Typical Applications

• AFFF foam systems on surface vessels
• seawater fire main / fire extinguishing circuits
• water curtain sprinkling
• water injection systems
• lines where seawater backflow may affect dosing, actuation, or system isolation

Selection Considerations

Selection should confirm:

• media type: seawater, AFFF mixture, or concentrate
• flange specification: MIL-F-20042 Class 150/250 as applicable
• operating pressure and available control pressure
• EP elastomer compatibility
• requirement for horizontal/vertical installation and maintenance access

Maintenance

Key inspection points include the diaphragm, internal check ports, seat cleanliness, sealing under backpressure, and deposits from seawater or AFFF residues.