Bengaluru metro prepares guidelines for resumption

Bengaluru metro prepares guidelines to make AC systems coronavirus-free

Namma Metro wants to make sure the existing air is not recirculated on the trains. DH FILE/IRSHAD MAHAMMAD

The central government hasn't yet allowed restarting metro trains but the BMRCL has begun preparations for working in the new normal, setting out guidelines to keep the coronavirus out of its air-conditioning systems. 

The public transporter has come out with a standard operating procedure (SoP) for the operation of the air-conditioning systems. That will involve increasing the intake of fresh air and providing complete exhaust of the air inside the metro stations. 

Namma Metro's Phase 1 infrastructure involves 40 stations, of which seven are underground, and 42-km-long metro lines, including a 9-km-long tunnel section. Maintaining the air-conditioning in the underground infrastructure, designed to maintain 27 (+/-1) degrees Celsius and a humidity of less than 55-65%, is a crucial task. 

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The SoP has been prepared based on the guidelines issued by the Central Public Works Department and the Indian Society of Heating, Refrigerating and Air Conditioning Engineers (ISHARE). It notes that the Namma Metro infrastructure is in line with the guidelines. 

To a question, Bangalore Metro Rail Corporation Limited (BMRCL) Managing Director Ajay Seth said the measures put an emphasis on the quantum of fresh air. "We have increased the quantum of fresh air required on trains and underground metro stations to make sure the existing air is not recirculated," he said. 

As per the SoP, metro AC units will run in the 'open mode' — bringing in 100% fresh air and taking out 100% of the exhaust "in order to avoid any recirculation and contamination" in all the times. During the peak hours, considering the increase in the footfall in station areas, the chilling system will be activated to balance the temperature.

The protocol lists the cleaning process for fans, air carrying units, exhausts and the entire system of the air-conditioner. Specifics on the amount of sodium hypochlorite, cresol and other chemicals needed to sanitise the system, as well as the number times the cleaning process has to be taken up, have been laid out. 

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