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Experimental Study on Effects of Nozzle Explosion Damage on Performance of Water Spray Fire Protection System of Ultra-high Voltage Transformer

In order to evaluate the effect of nozzle explosion damage on the performance of water spray fire protection system of ultra-high voltage (UHV) transformer, experiments were conducted with 0%, 10%, 30%, 50% of falling nozzle to simulate the damage of explosion on water spray fire protection system. The effects of the failure of different ratios of nozzles on the water mist envelope effect, nozzle pressure and pipeline flow rate of UHV transformers were analyzed. The results showed that the nozzle pressure and pipeline flow rate of water spray fire protection system were significantly affected by the proportion of falling nozzles. When the proportion of falling nozzles exceeded 10%, the working pressure of most nozzles fell below the minimum working pressure specified by the standard. The range of the sprinklers decreased and the coverage area was reduced. Meanwhile, the water spray fire protection system cannot effectively envelop the transformer. The firefighting water in the fire branch pipe was sprayed to the transformer body and its surroundings in the form of the water jet, which did not have the fire extinguishing ability through the water mist envelope. It may cause a hot oil fire, risk of boiling, splashing, or expanding fire. In actual projects, it is recommended to take protective measures such as explosion-proof and high-temperature resistant spray nozzles or spraying fire-resistant coatings on spray nozzles and pipelines, which could avoid or reduce the damage to the spray nozzles caused by explosion and high temperature during fire. Thus, it could improve the effectiveness of water spray fire protection system.