Flanged Safety Valves

Proportional Lift Safety Valves

A proportional lift safety valve is a flanged spring-loaded safety valve that lifts its disc gradually as pressure rises, relieving in proportion to the pressure increase.

It is used on liquid circuits, pump outlets, heat exchangers and low-to-medium capacity steam and gas applications. The product range includes PN40 models from DN15 to DN100.

DN15 – DN100size

PN16 / PN40pressure class

0.2 – 40 barsetting (by size and spring)

EN ISO 4126-1design basis

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Main Applications

Liquid circuits and pump outlets
Heat exchangers and heaters
High-temperature water systems
Pressure vessels
Process lines

Technical Data

Lift type	Proportional lift, spring-loaded
Connection	Flanged inlet and outlet; form B1
Flange standard	PN16: EN 1092-2 · PN40: EN 1092-1
Sizes	DN15 … DN100
Set pressure	About 0.2–40 bar (by size and spring)
Cast iron temperature	−10 / +300 °C
Cast steel temperature	−10 / +450 °C
Stainless temperature	−60 / +400 °C
Design basis	EN ISO 4126-1, AD 2000-A2, VdTÜV 100
Options	EPDM bellows, balanced stainless bellows, closed lever

Material Options

Part	PN16 · cast iron	PN40 · cast steel	PN40 · stainless
Body	EN-GJL-250	GP240GH+N (1.0619+N)	GX5CrNiMo19-11-2 (1.4408)
Seat	1.4571	1.4571	1.4571
Disc	1.4122	1.4122	1.4571
Spring	51CrV4 (1.8159)	51CrV4 (1.8159)	X10CrNi18-8 (1.4310)

Which material? A proportional lift valve gives stable relief on liquids; for high-capacity steam relief a full lift type is preferred. Values come from the flanged safety valve manufacturer sheet.

Advantages

Stable Relief

Suited to liquids

Three Body Materials

Cast iron, steel, stainless

Wide Setting

0.2 – 40 bar

Bellows Option

Back-pressure balancing

Construction and Design Features

Flanged body
Spring and adjusting screw
Disc and seat
Bonnet and lever (depending on model)

Send the size, pressure class, set pressure, fluid and capacity; we will confirm a suitable proportional lift valve.

How to Choose?

Size and flangeChoose DN and flange standard.
Pressure classSet PN16 or PN40 and the set pressure.
Fluid and temperatureState liquid, steam or gas and temperature.
Body and bellowsChoose cast iron, steel or stainless and bellows need.

Complementary Products

Pressure Gauges Steam Separators Thermodynamic Steam Traps Metal Bellows Expansion Joints Steel Flanges Pressure Measurement and Control Equipment

Why ORFA?

Since 1985Over 40 years of experience in supplying industrial piping equipment.

Technical ConsultancyTechnical support on valve capacity calculation.

Delivery from StockStock and lead time for proportional lift valves are confirmed quickly.

Compatibility CheckSteel Flanges for flange connections from the same point.

In This Group

Other Flanged Safety Valves

Full Lift Safety Valves

Full lift safety valves are flanged safety valves that open fully at the set pressure for high discharge capacity.

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Our Products

Our Proportional Lift Safety Valves

ORFA supplies proportional lift safety valves in a range of pressure classes, sizes and connection types to suit your application. Descriptions, technical specifications, materials and dimension tables are available on each detail page.

Proportional Full-Lift Safety Valve

Proportional full-lift safety valve: flanged, ductile iron PN16 (300 °C), cast steel PN40 (450 °C) and stainless PN40 (400 °C), DN15–DN100, open / closed cap. For liquids.