How do I select the correct FV flash vessel size for my application?

Sizing depends on three parameters: upstream pressure (steam trap or boiler pressure), flash steam pressure (desired or existing), and condensate/blowdown flowrate in kg/h. Spirax Sarco provides sizing charts to match these conditions to the appropriate vessel size (FV6 through FV18).

Can this flash vessel handle full vacuum conditions?

Yes, all FV series flash vessels are designed to withstand full vacuum, making them suitable for systems where vacuum conditions may occur during shutdown or process upsets.

What safety valve connection is provided, and how should it be sized?

Each vessel includes a dedicated safety valve connection. However, the safety valve size should not be assumed to match the connection size—sizing and selection must comply with applicable National and Local Regulations.

What is the recommended installation orientation for the FV flash vessel?

The vessel must be mounted with the flash steam outlet at the top. A float trap is recommended at the condensate/residual blowdown outlet for proper drainage.

Are ASME B16.5 flanged connections available?

Yes, while standard options include BSP screwed and EN 1092 PN16 flanged connections, ASME B16.5 Class 150 or Class 300 flanges and NPT threads are available on request.

SPIRAX SARCO · FLASH VESSELS

Spirax Sarco FV Flash Vessel – ASME VIII Pressure Vessel for Steam Heat Recovery

Name: Spirax Sarco FV Flash Vessel – ASME VIII Pressure Vessel for Steam Heat Recovery
Brand: Spirax Sarco

Spirax Sarco FV Flash Vessel for boiler blowdown & condensate heat recovery. ASME VIII certified, 14 bar g rated. Available at PC Engineering India.

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Overview

The Spirax Sarco FV Flash Vessel is an ASME VIII Division 1 certified pressure vessel engineered for efficient separation of flash steam from condensate or boiler blowdown. Its free-draining design prevents waterlogging and ensures reliable operation in demanding industrial steam systems.

These flash vessels are purpose-built for boiler blowdown heat recovery applications where clean separation of flash steam is critical to avoid contamination of boiler feedtanks and heat transfer surfaces. The low separation velocity design produces drier steam, improving downstream equipment performance and energy recovery efficiency.

The FV series is available in five sizes (FV6, FV8, FV12, FV15, FV18) to accommodate varying condensate and blowdown flowrates. Each unit is supplied with provisions for pressure gauge, safety valve, and inspection covers, meeting European Pressure Equipment Directive 2014/68/EU requirements.

Key Features

Designed and constructed to ASME VIII Division 1 2004 + ADD06
Compliant with European Pressure Equipment Directive 2014/68/EU
Free-draining construction — essential for blowdown applications
Low separation velocity for drier flash steam output
Withstands full vacuum conditions
Multiple connection options: BSP screwed, EN 1092 PN16 flanged, ASME B16.5 Class 150/300
Integrated connections for pressure gauge, safety valve, and inspection covers

Specifications

Parameter	Value
Design Standard	ASME VIII Division 1 2004 + ADD06
Maximum Design Pressure	14 bar g
Maximum Design Temperature	198°C (saturation)
Minimum Operating Temperature	-10°C
PN16 Flange Rating	13.3 bar g @ 198°C
Class 150 Flange Rating	13.8 bar g @ 198°C
Vacuum Rating	Full vacuum capable
Shell Material	ASTM A106B (C. Max. 0.25%)
End Cap Material	ASTM A234 WPB
Flange/Nozzle Material	ASTM A516-70 / A105N
Available Sizes	FV6, FV8, FV12, FV15, FV18
Flash Steam Outlet	2" (FV6) to DN150 (FV15/FV18)
Weight Range	45 kg (FV6) to 193 kg (FV18)

Applications

- Boiler blowdown heat recovery systems - TDS control blowdown flash steam recovery - Condensate flash steam recovery for low-pressure steam systems - Industrial steam plants requiring energy-efficient flash steam separation - Process plants with high-pressure condensate systems

Frequently Asked Questions

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Contact PC Engineering for pricing, availability, and technical support for Spirax Sarco FV Flash Vessels. Call us or fill in our inquiry form — our engineers will respond within 24 hours.

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