All BE Overpressure Blast Valves are subjected to extensive testing during development, manufacturing and assembly, in order to ensure superior quality.

The following report is a summary of the basic performance test each valve has to withstand. for additional data contact your supplier.

The BE Performance Tests are executed in the factory's modern test laboratories as well as by the Standards Institution of Israel.

The BE Performance Tests are based on the Israeli and Swiss Standards as minimum requirements and in many cases exceed them. Beside the tests described herein, there are numerous other specific performance tests, in the scope of ensuring proper function of the valves in all extreme conditions.

The following tests are the most important test procedures, named "The Basic set" and include:

1. Pressure drop
2. Shut-off pressure
3. Closing-airflow
4. Blast Wave Durability
5. Closing time
6. Peak excess pressure
7. Impulse
8. Leakage
9. Shock Durability
10. Coating
11. Thermal Resistivity

In the following pages we will present the test procedures and methods of measuring the "Basic set", according to the following scheme.

Each test procedure contains the following subparagraphs:

a) Definitions
- Background information on the necessity of the test
- Analysis of measurement and units

b) Passing criteria
- Required values supported by different National Standard Institutions (Israeli / Swiss Standard Institutions, DIN, ISO, etc.).
- BE applicable passing criteria for each test.

c) Test procedure
- Test description
- Test data

The Overpressure Valve is intended to maintain a specified overpressure within the protected area, in order to prevent the penetration of war gases and dangerous materials.

The pressure drop is measured in Pa.

Israeli regulations demand at least 120 Pa of overpressure in the protected area in filtration mode and maximum 300 Pa in ventilation mode. (Ventilation air quality = 2.67 x filtration air quantity.

Swiss regulations demand at least 50 - 70 Pa overpressure in filtration mode and maximum 250 Pa in ventilation mode (with a ventilation:filtration ratio of 2:1).

BE Blast Valves with Prefilter are tested according to the Israeli and Swiss Regulations.

The airflow through the valve is measured by precise Venturi-Tubes and the differential pressure on the valve by wall pressure tapping manometers according to ISO 5167-1.

The shut-off pressure is the differential pressure (measured on the valve) at which the valve closes when overpressure or underpressure slowly increases. The shut-off pressure must be low enough to protect the shelter population from being harmed by the blast waves.

The shut-off pressure is measured in Pa.

Israeli regulations for 3 bar valves:
Shut-off pressure for overpressure and underpressure: Pschl < 10 kPa

Swiss regulations for 1 bar valves:
Shut-off pressure for overpressure and underpressure: Pschl < 10 kPa

BE Blast Valves are tested for
shut-off pressure at overpressure and underpressure: Pschl < 10 kPa

The shut-off pressure is measured according to ISO 5167-1.

The closing-airflow is the maximum permitted airflow which causes the valve to close. The closing-airflow is measured in m³/h.

According to Israeli and Swiss regulations the 3 bar valve must close at max. 400% of the nominal airflow. According to Swiss regulations the 1 bar valve must close at maximum 300% of the nominal airflow.

BE 3 bar and 1 bar valves are checked to the corresponding regulation.

The airflow is measured with Venturi-tubes, according to ISO 5167-1.

In order to protect the shelter-residents effectively from blast waves resulting from explosions, the valve must withstand several consecutive blast waves.

Israeli Regulations: The valve must withstand 4 blast waves at the side-on pressure of 3 bar. After these 4 blast waves the valve and the prefilter should not show any damage which may affect its proper function.

Swiss Regulations: The valve must withstand 4 blast waves at the side-on pressure of 1 bar, without causing damage that would affect its function. The pressure drop on the valve should not change by more than 20%.

BE Blast Valves with Prefilter are exposed to 6 standard blast waves (2 extra).

The valve is mounted on the BE shock tube and is exposed to the blast waves. The valve is kept open before each wave in order to simulate ventilation mode. Usually the pressure drop has changed 3 - 5 % after the 6 blast waves.

The pressure drop is measured according to ISO 5167-1.

The closing time (ts) is the time the valve takes to close under the influence of a blast-wave. The valve must kept open as in ventilation mode. The closing time has to be as short as possible in order to fully protect the shelter-occupants and all the equipment.

The closing time (ts) is measured from the moment the blast wave begins till the amplitude's firts zero crossing.

The closing time is measured in ms.

Israeli Regulations: Less than 4 ms for 3 bar valves

Swiss Regulations:  Less than 4 ms for 1 bar valves

BE Overpressure Valves (1 and 3 bar) are tested to the above-listed vriteria.

For measuring the closing time the valve is mounted onto the BE shock tube and is exposed to the respective standard blast wave.

With the help of fast pressure transducers the closing time is indicated on the stroge digital recorder and transmitted to the computer.

The peak excess pressure (Psp) is the maximum pressure measured behind the valve during its closing aciton.

The peak excess pressure is measured in kPa or bar.
100 kPa = 1 bar

For the 3 bar valve the peak excess pressure may reach 2.0 bar, according to Israeli Regulation.

For the 1 bar valve the peak excess pressure may reach 1.0 bar, according to Swiss Regulation.

For pressure peak measurement the blast valve has to be measured without the Prefilter.

BE Overpressure Blast Valves (1 and 3 bar) are tested to the above-listed criteria.

For measuring of the peak excess pressure the valve is mounted onto the BE shock tube and is exposed to the respective standard blast wave. The peak excess pressure is sampled from the pressure transducer by a storage digital oscilloscope and transmitted to the computer.

The impulse ( I ) is the integral of the penetrating pressure / time gradient during the closing time of the valve. This is probably the most important indicator regarding the quality of a valve.

The impulse is shown in Pa x s or bar x ms. 100 Pa x s = 100 Ns/m² = 1 bar x ms

Both the Israeli and the Swiss Regulations allow an impulse of max. 150 Pa x s for all kids of valves.

BE Overpressure Valves (1 and 3 bar) are tested to the above-listed criteria.

The Impulse ( I ) is calculated from the penetrating pressure measured behing the valve and the closing time.

For measuring the penetrating pressure and the closing time, the valves is exposed in the shock tube to the applicable standard blast waves.

Using very fast pressure-sensors the closing time and the pressure are transmitted through the storage oscilloscope to the computer for calculation.

Leakage is the air-volume that passes a valve that is being closed by a blast wave. The leakage is measured in m³/h or in % of the nominal airflow.

The Israeli and Swiss Regulations allow a leakage of 100% for all valves, i.e. the air-volume that may pass the valve during closing is equal to the valve's nominal airflow.

BE Valves with Prefilter (1 and 3 bar) are tested to the above-listed criteria.

After exposure to standard blast wave the valve is closed. The pressure drop and the time during which this pressure drop occurs is measured. Using these two values the leakage is calculated.

The valve has been designed to withstand all expected shocks and vibrations in a shelter. After withstanding a shock, there must not be any failure in operation.

Israeli Regulations for 3 bar valves:

max. velocity:             1.5 m/s
max. acceleration:       60 m/s²=6 g
number of shocks:       9

Swiss Regulations for 1 bar valves:

max. velocity:             0.63 m/s
max. acceleration:       63 m/s²=6.3 g
number of shocks:       6

The valve is mounted onto a shock-test machine in a position to simulate its typical mounting position in a shelter and is tested under the above-mentioned conditions. No effects on proper operation may appear.

In addition as an alternative test the valve is exposed to vibrations of 10 g for a duration of 60 sec.

No signs of damage may appear on the valve.

The coating must protect the valve sufficiently against corrosion, so as to ensure perfect functioning after storage for many years in possibly hot and damp shelters.

According to Swiss Regulations the coating of 1 bar valves must have a thickness of at least 60 µm. The parts that have been treated with surface coating must not show any signs of corrosion after stroge for a period of 2 weeks in a salt-water mist (3% NaCI-solution).

The cross cut test, according to ISO 2409, may not exceed class 2.

The BE valves are first phosphatized (1 µm) and then are protected with a 90 µm Polyester-Epoxy coating.

No signs of corrosion may appear after storage of 2 weeks in a salt-water mist. (A 5% NaCI-solution is used to simulate coastal environment.) The cross cut test is performed according to ISO 2409.

The valves may not be affected in their operation by thermal radiation.

According to Swiss Regulations all valves must be designed to withstand thermal waves of 200ºC with a duration of 5 sec.

According to Israeli Regulations the valves have to withstand a thermal test at 100ºC for a duration of 10 min.

The valve is placed for 10 min. into an oven at a temperature of 100ºC and then for 10 sec. at 200ºC. No signs of damage may appear upon it.