Air Release & Check Valves - 33VB Seawater Vacuum Breaker Valve | Cla-Val

Cla-Val 33VB Seawater Vacuum Breaker

The Cla-Val 33VB is a vacuum breaker valve designed for seawater networks, primarily in fire protection systems and pipelines subject to periodic draining. It is installed at high points to admit air when negative pressure develops, minimizing the risk of vacuum-induced pipeline collapse.

Operation

The large air inlet allows unrestricted air entry during pipeline draining. The 33VB is not intended for continuous air release under pressure; for that function, a dedicated air release or combination air valve is required.

Technical Specifications

• Media: Seawater
• Application: Seawater service fire protection systems
• Connection: NPT or flanged
• Standard: ANSI
• Pressure classes: 150 lbs / 300 lbs
• Body material: Ductile iron
• Function: Air admission under vacuum conditions

Applications

• Seawater fire protection networks
• Intake/discharge pipelines in port facilities
• Seawater cooling systems
• High points in piping with vacuum risk
• Lines drained for maintenance

Selection Criteria

Selection is based on ANSI class, connection diameter, pipeline evacuation rate, allowable vacuum, and material compatibility with chlorides. For seawater, corrosion protection, galvanic compatibility, and inspection schedules must be considered.

FAQ

Does it vent air during filling?
Not as a primary function. It is a vacuum breaker.

Where is it installed?
At high points or locations where draining may induce vacuum.

What does it protect?
The pipeline from negative pressure and potential mechanical deformation.