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Pressure/Vacuum Relief Valve deflagration- and endurance burning-proof

  • extreme tightness, resulting in lowest possible product losses and reduced environmental pollution
  • set pressure close to opening pressure for optimum pressure maintenance in the system
  • due to 10% technology, set pressure is close to opening pressure for optimum pressure maintenance in the system as compared to conventional 40% or 100% technology
  • valve opens later and closes earlier than conventional valves
  • valve pallet is guided inside the housing to protect against harsh weather conditions
  • PROTEGO® flame arrester unit provides protection against atmospheric deflagrations and endurance burning
  • integrated PROTEGO® flame arrester unit saves space and weight and reduces costs
  • PROTEGO® flame arrester unit is protected from clogging and sticky substances caused by product vapors
  • minimum pressure loss of the PROTEGO® flame arrester unit
  • can be used as a protective system in areas with potentially explosive atmospheres in accordance with ATEX
  • high flow capacity due to larger FLAMEFILTER® cross section
  • flameproof condensate drain
  • maintenance-friendly design
  • modular design enables replacement of individual FLAMEFILTER® discs and valve pallet

Function and Description

The deflagration-proof and endurance burning-proof VD/SV-HR type PROTEGO® valve is a highly developed combined pressure/vacuum relief valve for high flow capacities with an integrated flame arrester. It is primarily used as a device for flame transmission-proof in-breathing and out-breathing in tanks, containers, and process equipment. The valve offers reliable protection against overpressure and vacuum, prevents out-breathing of product vapor and in-breathing of air almost up to the set pressure, and protects against atmospheric deflagration and endurance burning if stabilized burning occurs. The PROTEGO® flame arrester unit is designed to achieve minimum pressure drop with maximum safety. The deflagration and endurance burning-proof PROTEGO® VD/SV-HR device is available for substances from explosion groups IIA to IIB3 (NEC group D to C MESG ≥ 0.65 mm).

If the set pressure is reached for a valve approved for explosion Group IIA (NEC group D), the valve starts to open and reaches full lift within 10% overpressure. This unique 10% technology nables a set pressure that is only 10% below the maximum allowable working pressure (MAWP) of the tank. After years of development, this typical opening characteristic of a safety relief valve is now also available for the low pressure range. Valves approved for explosion group IIB3 (NEC group C) function proportionally, so the set pressures should be selected in relation to the proportional behavior (such as a 10%, 40%, or 100% overpressure from the set pressure to the relieving pressure at which the required flow performance is reached).

The tank pressure is maintained up to set pressure with a tightness that is above the normal standards due to our stateof- the-art manufacturing technology. This feature is ensured by the valve seats made of high quality stainless steel and with individually lapped valve pallets (1), or with an air cushion seal (2), in conjunction with high quality FEP diaphragm. The valve pallets are also available with a PTFE seal to prevent them from sticking when sticky substances are used and to enable the use of corrosive fluids. After the overpressure is released, the valve re-seats and provides a tight seal.

If the set pressure is exceeded, explosive gas/product vapor/air mixtures are released into the atmosphere. If this mixture ignites, the integrated PROTEGO® flame arrester unit (3) prevents flame transmission into the tank. If additional mixture continues to flow and stabilized burning occurs, the integrated flame arrester unit prevents flashback as a result of endurance burning. The valve is protected and also fulfils its function under these severe conditions. The spring-loaded weather hood opens as soon as the melting element (4) melts.

The valve can be used at an operating temperature of up to +60°C / 140°F and meets the requirements of European tank design standard EN 14015 (Appendix L) and ISO 28300 (API 2000).

Type-approved in accordance with the current ATEX Directive and EN ISO 16852, as well as other international standards.


To select the nominal size (DN), please use the flow capacity charts on the following pages

DN80 / 3"100 / 4"
Dimensions in mm / inches

Material selection for housing

Design AB
HousingSteelStainless Steel
Valve saetsStainless SteelStainless Steel
Weather hoodStainless SteelStainless Steel
Flame arrester unitAA
Special materials upon request

Material combinations of flame arrester unit

Design A
FLAMEFILTER® cageStainless Steel
FLAMEFILTER®Stainless Steel
Special materials upon request

Material selection for pressure valve pallet

Design ABCD
Pressure range [mbar]
[inch W.C.]
+3.5 up to +5.0
+1.4 up to +2.0
>+5.0 up to +14
>+2.0 up to +5.6
>+14 up to +35
>+5.6 up to +14
>+14 up to +35
>+5.6 up to +14
Valve palletAluminiumStainless SteelStainless SteelStainless Steel
SealingFEPFEPMetal to MetalPTFE
Special material as well as higher set pressure upon request

Material selection for vacuum valve pallet

Design ABCD
Vacuum range [mbar]
[inch W.C.]
-2.0 up to -3.5
-0.8 up to -1.4
<-3.5 up to -14
<-1.4 up to -5.6
<+14 up to +35
<-5.6 up to -14
<-14 up to -35
<-5.6 up to -14
Valve palletAluminiumStainless SteelStainless SteelStainless Steel
SealingFEPFEPMetal to MetalPTFE
Special material as well as higher set vacuum upon request

Selection of explosion group

MESGExpl. Gr. (IEC / CEN)Gas Group (NEC)
> 0,90 mmIIAD
≥ 0,65 mmIIB3C
Special approvals upon request

Flange connection type

EN 1092-1; Form B1
ASME B16.5 CL 150 R.F.
other types upon request

Design Types and Specifications

Any combination of vacuum and pressure levels can be set for the valve
The valve discs are weight-loaded.

Pressure/vacuum relief valve, basic design


Additional special devices available upon request


Pressure: +3.5 mbar +35 mbar
+1.4 inch W.C. +14 inch W.C.
Vacuum: -2.0 mbar -35 mbar
-0.8 inch W.C. -14 inch W.C.
Higher and lower settings upon request

Flow Capacity Chart

The flow capacity charts have been determined with a calibrated and TÜV certified flow capacity test rig. Volume flow V in (m³/h) and CFH refer to the standard reference conditions of air ISO 6358 (20°C, 1bar). For conversion to other densities and temperatures refer to Sec. 1: “Technical Fundamentals”.