MODELING HYPERBARIC CHAMBER ENVIRONMENT AND CONTROL SYSTEM

Deep water activities are essential for many industrial fields, for instance in repairing and installation of underwater cables, pipes and constructions, marine salvage and rescue opera- tions. In some cases, these activities must be performed in deep water and hence require special equipment and prepared and experienced personnel. In some critical situations, re- motely controlled vehicles (ROVs) can't be used and a human diver intervention is required. In the last case, divers are required to perform work at high depths, which could be as low as 300m below the water surface. Usually, this is the limit depth for commercial diving and when operations must be carried out even deeper, ROVs remain only possibility to perform them. In the past, the safety regulations were less strict and numerous operations on depth of 300-350 meters of seawater were conducted. However, in the beginning of the 90s gov- ernments and companies started to impose limits on depths of operation; for instance, in Norway maximum operational depth for saturation divers is limited to 180 meters of sea- water (Imbert et al., 2019). Obviously, harsh environmental conditions impose various limitations on performed activi- ties; indeed, low temperature, poor visibility and high pressure make it difficult not only to operate at depth, but even to achieve the point of intervention. One of the main problems is related to elevated pressure, which rises for about 1 bar for each 10 meters of water depth and could achieve up to 20-25 bars at required depth, while pressure inside divers\u2019 atmospheric diving suites must be nearly the same. Considering this, there are several evident limitations. First is related to the fact that at high atmospheric pressure oxy- gen becomes poisonous for human body and special breath gas mixtures are required to avoid health issues. The second one is maximum pressure variation rate which would not cause damage for the human body; indeed, fast compression or decompression could easily cause severe damages and even death of divers. Furthermore, surveys found that circa 1/3 of divers experience headache during decompression which usually last for at least several hours and up to several days (Imbert et al., 2019). The same study indicates that majority of the divers experience fatigue after saturation and it lasts on average more than 4 days before return to normal. Obviously, risk of accidents increases with high number of compression- decompression cycles. To address these issues, in commercial deep water diving the common practice is to perform pressurization only one time before the start of the work activity which typically lasts 20-30 days and consequent depressurization after its end. Hence, divers are living for several weeks in isolated pressurized environments, typically placed on board of a Dive Support Vessel (DSV), usually barge or a ship, and go up and down to the workplace using submersible decompression chamber also known as the bell. While long-term work shifts provide numerous advantages, there is still necessity to perform life support supervision of the plant, the bell and the diving suits, which require presence of well qualified personnel. Currently, most of training activities are performed on empty plant during idle time, but obviously this approach is low efficient and costly, as well as accom- panied by the risk to broke equipment. To address such issues, this research project proposes utilization of simulator of plant and its life support system, devoted to train future Life-Support Supervisors (LSS), taking into account gas dynamics, human behaviour and physiology as well as various aspect of opera- tion of saturation diving plants