ESD testing

Calculate the spark energy (ESD test) for a spark generated under the following conditions C = 0.005 pF, V = 10000 V... 

In electrostatic discharge (ESD) tests, the amount of energy that is required to ignite explosives by electrostatic stimuli is determined. Most explosives have low electrical conductivity. Therefore, the potential of the electrostatic pulse has to be high to generate a sparkover. Figure 1.4 illustrates the principle setup of an ESD testing device. 

Table 1.4 Exemplary ESD test results for some azide compounds and other...

The combination of conductive flooring 7/ia conductive footwear is the preferred method of grounding. Untreated concrete flooring with conductive footwear is usually adequate, but its conductivity should be measured (Fowler and Klein, Static Phenomena and Test Methods for Static Gontrolled Floors, EOS/ESD Symposium Proceedings, pp. 27-38, 1992). Where this method is impractical, personnel grounding devices are available. 

ESD systems should be designed to be sufficiently reliable and fail safe that a (1) accidental initiation of the ESD is reduced to acceptable low levels or as low as reasonably practical, (2) availability is maximized as a function of the frequency of system testing and maintenance, and (3) the fractional MTBF of the system is sufficiently large to reduce the hazard rate to an acceptable level, consistent with the demand rate of the system. 

The utilization of a fail steady - fail safe mode may allow an undetected failure to occur unless additional instrumentation is provided on the ESD system components or unless the system is constantly fully function tested. The prime feature of a full fail close or fail open failure mode is that it will immediately indicate if the component is functioning properly. 

The model has been claimed to predict the log BB values at a rate of 700 molecules per min, some two orders of magnitude faster than the calculations of Keserii and Molnar. To test the likely accuracy of such predictions, the authors took 105 compounds for which experimental descriptors were used in constructing equation (48) and calculated their log BB values using same with descriptors calculated by the method of Platts and workers. The observed and calculated values agreed with ESD = 0.294, thus indicating that Platts calculation method can be used in conjunction with equation (48) to predict further log BB values faster with an estimated accuracy of around 0.30 to 0.35 log units. 

HMTD displays some interesting characteristics. It was surprisingly fairly insensitive to impact compared to PETN and TATP. The impact sensitivity measured lay between the values for PETN and RDX. Even more surprising was the ESD sensitivity. HMTD is a very line powder when isolated. It has an appearance almost like that of talc. Fine powders are well known for being prone to static charge buildup. When transferring from one container to another, the static buildup in the HMTD was obvious by the way the powder stuck to the walls of the vessels involved. HMTD was more static sensitive than either of the standards tested, but it was less static sensitive than TATP. This was unexpected, and at the moment cannot be explained. The values obtained seem to indicate that HMTD has only moderate static sensitivity. 

Figure 1. Results of test retrievals canied-out starting from observations generated with the RFM. Each panel reports the reference profiles (profiles) with the corresponding retrieved data points (left plots) as well as the deviations (dev.) of the retrieved data points from the reference profiles (oenter and right plots). The Estimated Standard Deviation (ESD) of the retrieved profiles is also reported as a solid line in the oenter and right plots.

Test Equipment and Software (EMC, ESD, Telcom, Environmental, and Safety), Compliance Engr., Annual, 2003. 

The sensitivity of K2DNABT was tested and was found to be very sensitive to impact, friction and ESD, as all primary explosives are. K2DNABT is more sensitive compared to lead azide, lead styphnate and DBX-1 (as shown in Tab. 1.3a). 

As is shown in Figure 6.4, the ESD values are greatly influenced by the particle size in these tests the sample must be carefully sieved prior to measuring. The finer the powder of a particular sample is, the higher the ESD sensitivity values are. Usually, compounds with ESD 0.1 J are classified as sensitive, those with ESD 0.1 J as insensitive. 

Operational environment checks should include those on power supplies, ambient temperature and humidity, vibration and dust levels, Electro-Magnetic Interference (EMI), Radio Frequency Interference (RFl), and Electrostatic Discharges (ESD) as relevant to the needs of the computer system. This list of operational environment requirements is by no means exhaustive, and may be extended or even reduced depending on what is known about the system. EMI and RFI might be tested with the localized use of mobile or cell telephones, walkie-talkie communications receivers/transmitters, arc welding equipment, and electronic drills. The aim is to test the vulnerability of the computer system to interference in situations that must be considered as normal working conditions. 

Powered wheelchairs have been reported to exhibit unintended movement. Wheelchair manufacturers and the US Food and Drug Administration Center for Devices and Radiological Health (FDA-CDRH) have examined the susceptibility of powered wheelchairs and scooters to interference from radio and microwave transmissions. These devices are tested at frequencies ranging from 26 MHz to 1 GHz, which is common for transmissions (e.g., radio, TV, microwave, telephones, mobile radios). Power wheelchairs incorporate complex electronics and microcontrollers which are sensitive to electromagnetic (EM) radiation, electrostatic discharge (ESD), and other energy sources. 

A further variation was proposed by the Finnish company Neste Oy and is at the stage of being tested in various ESD applications by Panipol, which attempted to prepare a melt processable polyaniline [61 ]. It still remains a matter of debate what the melt behavior they observed resulted from, but it was evident that the resulting blend again is a two-phase system with nanosize network structures formed by the dispersed PAni phase. 

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