# Influence of the Pyrotechnic Igniter Composition Aging on Explosion Parameters of Dispersed Dusts
## 4 Discussion  
The measured explosion parameters of the samples indicate that aging of the igniters may affect their functional parameters. In the KV 150M2 explosion chamber, we detected a 4-7% decrease in the explosion pressure when using Igniter 2 (manufactured in 2018) and a decrease in the pressure increase rate of 17-29% (K\({}_{\text{st}}\) constant) in a standard sample of _Lycopodium clavatum_. For Igniter 1 (manufactured in 2021), the explosion parameters corresponded with the standard characteristics according to the ASTM E1226a Standard.  
Measurement of the magnesium sample in the 20 L sphere explosion chamber identified that the value of the explosion pressure P\({}_{\text{max}}\) was reduced by 3-6%, while for the  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Concentration**} & \multirow{2}{*}{**Parameter**} & **Igniter 1** & **Igniter 2** & \multirow{2}{*}{**Deviation**} \\  & & **<1 Year from** & **2-3 Years from** & & \$ \\  & & **Date of** & **Date of** & & \% \\  & & **Manufacture** & **Manufacture** & & \\ \hline \multicolumn{4}{c}{_Lycopodium clavatum_, characteristic particle size 30–32 \(\upmu\)m (365 L chamber)} \\  & P\({}_{\text{max,250}}\) (bar) & 7.21 & 7.03 & \(-\)2.5 \\
250 g\(\cdot\)m\({}^{-3}\) & (dP/dt)\({}_{\text{max, 250}}\) & 182.7 & 148.6 & \(-\)18.7 \\  & \({}_{\text{St, 250}}\) & 130.6 & 106.2 & & \\  & P\({}_{\text{max, 500}}\) (bar) & 7.43 & 6.88 & \(-\)7.4 \\
500 g\(\cdot\)m\({}^{-3}\) & (dP/dt)\({}_{\text{max, 500}}\) & 208.5 & 149.4 & \(-\)28.3 \\  & K\({}_{\text{st, 500}}\) & 149.0 & 106.8 & & \\  & (bar\(\cdot\)m\(\cdot\)s\({}^{-1}\)) & & & \\  & Magnesium powder \(<\) 45 \(\upmu\)m (\(-\)325 mesh), median 33.1 \(\upmu\)m (20 L chamber) & & & \\  & P\({}_{\text{max, 250}}\) (bar) & 6.2 & 6.0 & \(-\)3.2 \\
250 g\(\cdot\)m\({}^{-3}\) & (dP/dt)\({}_{\text{max, 250}}\) & 453 & 268 & \(-\)40.7 \\  & K\({}_{\text{st, 250}}\) & 123 & 73 & \\  & (bar\(\cdot\)m\(\cdot\)s\({}^{-1}\)) & & & \\  & P\({}_{\text{max, 500}}\) (barigniters with more than 2 years from the date of manufacture, the decrease in the explosion constant K\({}_{\rm st}\) was 20-40%.  
For igniters with more than 2 years from the date of manufacture, measurement of the sample of benzoic acid in the 20 L sphere explosion chamber recorded a decrease of 2.5-5.5% in the case of explosion pressure \(P_{max}\), as well as a decrease of 4-20% in the case of explosion constant K\({}_{\rm st}\).  
The manufacturer specifies the consumption period of 2 years for the igniters. Two types of igniters were therefore selected for this study. Igniter 1 was used within 1 year from the date of manufacture. Igniter 2 was used for 2-3 years from the date of manufacture. The EN 14034 Standard determines permissible deviation of the Pmax value of 10% (for each concentration in the experiment described in the current paper). The results in Table 1 show that the Pmax value of the igniters meets the requirement of the maximum tolerance even after expiration of their consumption time.  
The tolerance for determining (dP/dt)\({}_{\rm max}\) depends on its value. Table 2 shows that, in the case of using the igniters after the specified expiration time, the value (dP/dt)\({}_{\rm max}\) for _Lycopodium clavatum_ and magnesium samples decreases below the permissible tolerance. Aging of the igniter does not have such a significant effect in the case of benzoic acid; the permissible deviation (dP/dt) max was exceeded for the sample of benzoic acid only at a concentration of 250 g\(\cdot\)m\({}^{-3}\).