Air Quality regulator

The study of air quality in the ship’s living cabin had been carried out. For the purpose of the study the Air Quality Regulator was designed and created. This device primary features are measuring and adjusting the parameters of air quality in the living premises by the following criteria: total quality in CO2 equivalent units, carbon dioxide content and hydrocarbon content.

Air Quality Regulator structural design

The device was tested for two months on board a gas carrier vessel which carried propylene. Measurements were made in the test cabin cabins and compared with outdoor air.

The regulator recorded the air quality parameters to the internal memory and maintained them within established limits by operating the ventilation damper in the test room. At the same time the specified comfort indicators were maintained: temperature and humidity. The damper software implemented Proportional controller by two parameters: temperature and content with a limitation by the hydrocarbon content in the outside air. If the concentration of hydrocarbon in the outside air did not exceed 50% TLV, the controller maintained the set comfort parameters. If the concentration was higher than the limit, then the ventilation damper kept closed and opened only if the hydrocarbon content in the room was greater than outside or outdoor concentration of the hydrocarbons dropped below 50% TLV.

The experiment showed:

  • Control of the air quality of the ship’s premises allows the maintaining of harmful content substances below TLV most of the time and with little excess during emergencies
  • During degassing of tanks, propylene content in the outside air has occasionally increased to 2250 ppm, which is 4.5 times higher than TLV. At the same time, the concentration of cargo vapor in the protected premisses did not exceed 700 ppm
  • The described prototype device is capable of performing the function of a cargo leak alarm. The device recorded leak of propylene that occurred due to poor repair of the emergency shut-off valve. During the incident,the propylene concentration in the outside air reached 800 ppm. At the same time its contents are in the test protected premisses it did not exceed 200 ppm due to the protective function of the subject device
  • During cargo operations, the hydrocarbon content in the indoor air did not exceeded TLV = 500 ppm
  • When the air conditioner air recirculation is set to more than 80%, carbon dioxide accumulates in the ship’s premises. Its concentration can quickly exceed the level set by the standards.

Conclusions:

  1. Indoor air quality control plays an important role in ensuring safety of the inhabitants as it allows to keep the content of harmful substances below the maximum most of the time and with little excess during emergencies.
  2. Quality measurement and control techniques need to be developed and implemented the indoor air
  3. The air quality control must be carried out simultaneously with the maintaining of the comfort microclimate indicators with the priority for keeping the indoor air safe.