Valves

Valves in an aquatic life support system provide isolation, control and automated actuation; elastomer and body material selection for seawater and ozone service is where valve specifications most often fail.

Types used

Butterfly valves for isolation on larger lines, the most common valve in aquatic filtration. Ball valves for smaller lines and tight shutoff. Diaphragm valves for throttling and chemical service. Check valves to prevent reverse flow. Multiport and automated valves for filter backwash sequencing. Actuated valves where controls operate the system.

Why specification matters

Elastomer selection is the failure point. Valve bodies are usually PVC or CPVC and generally fine. The seat and seal material is where things go wrong. EPDM performs well in many aquatic applications and degrades in ozone. Viton handles ozone and costs more. A valve with the wrong elastomer in an ozone line fails, and the failure is not always obvious before it causes a problem.

Isolation determines whether the facility can be maintained. Every piece of equipment needing service needs valves allowing removal without draining the system. This is routinely value-engineered out and regretted for the life of the building. It is worth defending during the bid.

Actuated valves belong to two scopes. An automated valve is mechanical equipment and a controls device. Actuator type, signal, fail position, and power all need coordinating between the mechanical and controls packages. Valves fall through this gap regularly.

Pressure rating and temperature interact. PVC and CPVC pressure ratings drop as temperature rises. A valve rated adequately at ambient may be marginal on a heated system.

Backwash valves see hard service. Filter backwash valves cycle constantly and take abrasive duty. Specifying general-purpose valves for backwash service produces early replacement.

How SIVAT helps

We review valve schedules against water chemistry, particularly ozone exposure, and confirm elastomer selection throughout. We check that isolation valves exist where equipment needs servicing, and coordinate actuated valve requirements between the mechanical and controls packages.

Valves are one example of where a coordinated equipment package creates value. Reviewing materials, elastomers, actuation, pressure ratings, and controls interfaces across the package reduces the risk of mismatches that can be missed when components are purchased separately.

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