Self-reclosing pressure venting device with fire protection function
DE 1-F90®
This makes it an excellent solution to be used particularly in transformer chambers as well as in high and medium voltage switchgear, where it has proved its effectiveness in various applications.
So far, protecting enclosed spaces with both fire and overpressure hazards has not only involved structural modifications and investing a lot of money. As will be explained later, the standard precautions still widely used today are, in particular cases, not appropriate to satisfy safety requirements.
The DE1-F90® module developed by rexotec AG is the first protective device on the market that was tested by an acknowledged German certification body and meets the requirements both for flameless pressure venting devices and for building components rated fire resistance class F90/EI90 (i.e. 90 minutes fire resistance duration).
The patented DE1-F90® system functions reliably as a flame arrestor, no matter what comes first: a fire or a rise in pressure.
Every pressure relief system automatically and mechanically reseals itself after an event and is just as tight as before.
The modular system offers simple and secure solutions for a wide range of applications.
Self-reclosing pressure venting device
Currently available protective solutions for facilities at risk of pressure rise as well as fire typically rely on pressure venting and subsequent sealing off of the affected compartment with self-closing fire barriers (e.g. fire doors or panels). The compartment is then tightly closed. If an explosion or pressure rise occurs after the original incident, venting is no longer possible. This can result in significant damage to property or even personal injuries.
The DE 1-F90® module has self-reclosing venting covers, which automatically reclose tightly immediately after each opening. If another pressure rise occurs the covers open as they did before. This operation can be repeated almost indefinitely, the function is completely mechanical with no error-prone electrical components.
This makes DE 1-F90® the only F90 building component currently on the market that ensures safe pressure venting at any time.
The module is also available as F30 or F60 version on request.
Verification of product characteristics
Tests carried out by a notified body proved that the DE 1-F90® system complies with EN1634-1 and 1634-3 requirements for F 90 building components.
At a temperature of 1,000 °C inside the fire compartment, the DE 1-F90® module safely prevented flame passage during fire resistance testing.
The tremendous energy absorption potential of the flame-quenching element developed by rexotec AG became evident already during the EC Type Examination tests for the scubex® series as flameless explosion venting device: while temperatures inside the housing reached approximately 1,500 °C in tests with 99.5 % aluminium dust, the surface temperature was measured to be below 100 °C.
Determination of the airflow volume
The airflow volume is measured for each version of our DE 1-F90® system. The resulting curve chart exactly shows the air or gas volume that passes through the module per unit time at a certain pressure.
This is the basis for determining the number of modules required for any given application.
Flow Simulation: we don’t guess but calculate
We use state-of-the-art flow simulation software already in the development phase of our products. It offers the possibility to calculate and visualize e.g. the rate and direction of propagation of a pressure wave as well as the resulting pressure or temperature at any point of the device.
The findings obtained with this method help us to both optimize our products and find appropriate protective solutions for our clients’ plants.
The picture clearly shows that most of the pressure wave released after the opening of the venting covers spreads out along the outer surface of the protected vessel, almost nothing is released into the surrounding area. The risk of damage to property or injury is significantly reduced.
Design of the necessary relief area for arc faults in medium and low voltage switchgear.
To ensure the protection of personnel and equipment, the installation standards IEC 61936-1 for high and medium voltage switchgear and IEC 60364 for low voltage switchgear must be considered in addition to the relevant product standards.
IEC 61936-1 requires that building constructions housing power installations with a rated voltage above 1 kV must withstand the internal pressure potentially caused by an arc fault. Electrical operating rooms for transformers and medium voltage switchgear must be included in the protection concept and equipped with adequately sized pressure relief devices.
It is advisable to calculate the static or dynamic pressure load, which can provide insights into the stress on the building structure. During the planning phase, calculating the expected pressure impacts of an arc fault according to Pilger can provide rough estimates for the required pressure relief.
Recommended procedure for determining appropriate protective measures:
- 1. Calculation of the weakest wall’s overpressure load capacity (Architect)
- 2. Pressure calculation according to Pilger based on the maximum allowable pressure load of the weakest wall
- 3. Determination of the required pressure relief area
The number of DE 1-F90® modules required in each case is determined by rexotec AG based on the calculation results.
Flexible and easy to use
The DE 1-F90® module is simply inserted into a wall opening of 600 mm x 600 mm and bolted directly to the wall. Several modules can be combined to form a larger element: an extremely space-saving solution, which almost disappears inside the wall.
Of course the DE 1-F90® module can also be used to upgrade existing facilities.
A side effect of the DE 1-F90® module is an improved noise insulation.
Technical information
- Fire resistance class F90 acc. to DIN 4102-2,
corresponding to E I90 acc. to DIN EN 13501-2 - completely dust-proof
- almost gas-tight (leakage < 0,2 m³/h)
- smoke-tight acc. to DIN EN 1634-3
- Operating temperature: -40 °C to 600 °C
- Vacuum stability: up to 200 mbarg / 20,000 Pa
- Opening pressure: default setting by manufacturer from 10 to 100 mbarg
- Opening path of the venting covers: ≤ 120 mm
- Dimensions according to drawing