Hy-Check Valve - 181M-2 | Cla-Val

Cla-Val 181M-2 Hy-Check Valve for AFFF Systems

The Cla-Val 181M-2 is a hydraulically operated Hy-Check type non-return valve, designed for marine AFFF systems on surface vessels. It permits unidirectional flow and closes automatically when supply ceases or backpressure develops, preventing reverse flow of foam solution into the circuit.

Operational Use

The 181M-2 is not intended as a standard inline check valve for general water networks. It is installed in firefighting circuits where reverse flow may impact:

• AFFF distribution integrity,
• system hydraulic balance,
• isolation of piping sections,
• correct downstream equipment activation.

Technical Classification

In the Cla-Val marine catalogue, the 181M-2 is listed as a Hy-Check Valve for AFFF Foam System. Available sizes are 4", 5", and 6", with flanged connections per MIL-F-20042 Class 250 and reference to MIL-P24589.

Difference from 181M-EP and 181PM-EP

• 181M-EP: Hy-Check Valve for sea water service.
• 181PM-EP: Power Hy-Check Valve for AFFF concentrate.
• 181M-2: Hy-Check Valve for AFFF foam system lines, in larger flanged sizes 4"–6".

Selection Criteria

Technical selection requires confirmation of flange class MIL-F-20042 Class 250, operating pressure of fire main or foam main, flow direction, AFFF mixture compatibility, and compliance with shipyard specifications.

Maintenance

Inspection should focus on seat cleanliness, free movement of internal mechanism, tightness under backpressure, and AFFF residue. Post-firefighting testing requires flushing, as foam residues may affect resealing and valve closure integrity.