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Vacuum Relief Valve deflagration-proof

  • requires only 10% overpressure to full lift
  • extreme tightness and hence least possible product losses and reduced environmental pollution
  • through 10% technology lower set vacuum can be reached which results in product loss reduction compared to conventional 40% and 100% overpressure technology vents (compare API 2000)
  • optimized flow performance
  • the valve disc is guided within the housing to protect against harsh weather conditions
  • can be used as protective system according ATEX in areas subject to explosion hazards
  • FLAMEFILTER® provides protection against atmospheric deflagration
  • FLAMEFILTER® integrated into the valve saves space, weight and reduces cost
  • FLAMEFILTER® protected from clogging through product vapour
  • PROTEGO® flame arrester unit has a low pressure drop
  • maintenance friendly design
  • modular design enables individual FLAMEFILTER

Function and Description

The deflagration proof V/SV-AD type PROTEGO® valve is a highly developed vacuum relief valve for high flow capacities with an integrated flame arrester unit. It is primarily used as a safety device for flame-transmission-proof in-breathing in tanks, containers, and process equipment. The valve offers reliable protection against vacuum and prevents in-breathing of air almost up to the set pressure; while at the same time protecting against atmospheric deflagration. The PROTEGO® flame arrester unit is designed to achieve minimum pressure drop with maximum safety. The deflagration-proof PROTEGO V/SV-AD valve is available for substances for explosion group IIB3 (C MESG ≥ 0.65 mm).

When the set vacuum is reached, the valve starts to open and reaches full lift within 10% overpressure. This unique 10% technology enables a set vacuum that is only 10% above the maximum allowable working vacuum (MAWV) 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.
The tank pressure is maintained up to the set vacuum with a tightness that is above to the normal standards due to our state-of-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 vacuum is balanced, the valve re-seats and provides a tight seal.
If the valve is used in atmospheres forming an explosive mixture with air and the mixture ignites, the integrated PROTEGO® flame arrester unit (3) prevents flame transmission into the tank. 

The standard design is tested 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). 

EU conformity according to the currently valid ATEX directive. Approvals according to other national/international regulations on request.


To select the nominal size (DN), please use the flow capacity chart on the following page

DN50 / 2"80 / 3"100 / 4"150 / 6"200 / 8"250 / 10"300 / 12"
a337 / 13.27395 / 15.55515 / 20.28713* / 28.07*808* / 31.81*925* / 36.42*946 / 37.24
b247* / 9.72*312 / 12.28358 / 14.09443 / 17.44520 / 20.47588 / 23.15588 / 23.15
Dimensions in mm / inches

Material selection for housing

Design ABC
HousingAluminumSteelStainless Steel
Heating jacket (V/SV-AD-H-...)SteelStainless Steel
Valve seatStainless SteelStainless SteelStainless Steel
CoverAluminum Stainless Steel Stainless Steel
FLAMEFILTER® Stainless Steel Stainless Steel Stainless Steel
Special materials upon request

Material selection for valve pallet

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 materials and higher pressure settings upon request

Selection of explosion group

MESGExpl. Gr. (IEC / CEN)Gas Group (NEC)
≥ 0,65 mm IIB3C
Special approvals upon request

Specification of max. operating temperature

≤ 60°C / 140°FTmaximum allowable operating temperature in °C
higher operating temperatures 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

The valve disc is weight-loaded.
There are two different designs:

Vacuum relief valve, basic design


Vacuum relief valve with heating jacket (max. heating fluid temperature +85°C / 185°F)


Additional special devices available upon request


Vacuum: -2.0 mbar -35 mbar
-0.8 inch W.C. -14 inch W.C.
Higher vacuum 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”.