The battery room in an IT environment is usually enclosed and have little room for ventilation. This poses a great risk for users as the toxic gases especially hydrogen, that is getting released from batteries when accumulated beyond a level (2% of total air volume PPM), (LLE), Low Level Explosion limit is highly combustible and any light spark causes explosion.
The UPS for which batteries are connected provides back up power to the load to which UPS is connected. In the event of long raw power outage, the batteries are drained and a situation of ‘Deep Discharge’ takes place. When the raw power is resumed, the batteries are put in charging mode and during this mode only toxic gases especially hydrogen is emitted. In the absence of any air circulation or fresh air, there are chances of hydrogen accumulation that poses great explosion risk.
To overcome the accumulation of hydrogen gas, a ventilation system that comprises of fresh air intake with suitable cooling and exhaust fan dedicated for battery room is being practiced. This when working, neutralizes the hydrogen thereby preventing any explosion due to accumulation of hydrogen. However, the exhaust system that comprises of rotating mechanical system , bound to fail if continuously used. Also the fresh air intake brings dust etc along with when the exhaust system is in operation. Hence there is a need to make it a “Demand Based Ventilation System” rather than a conventional exhaust system.
Demand Based Ventilation System works on the basis of hydrogen accumulation and if it crosses a set threshold, it switches on the fan and when the hydrogen level goes below the safe limit, the fan is switched off. This way the exhaust fan is protected (and in some cases energy savings is achieved) and also the hydrogen accumulation is avoided.
Thittanix instruments has Hydrogen based Control system for ventilation fan applications. It has a micro controller that reads the sensor value continuously and in case of crossing a threshold limit, gives command to the ventilation fan to start. When the hydrogen value goes below a safe limit, the fan will be automatically switched off. If the hydrogen value crosses another threshold, an alarm is initiated. The threshold limits and proportional band can be set with password protected programming. The value of hydrogen is displayed in the front panel.
In this Control system, a timer function is also provided. With this timer function, the ventilation fan can be made to come on fixed time intervals (settable from 10 Minutes to 360Minutes) and the duration also can be set from one minute to 30 minutes. With this function, irrespective of hydrogen accumulation, the ventilation fan can be controlled to achieve proper ventilation in the battery room.