Calculate Hydrogen Gas Emissions

Calculate Hydrogen Gas Emissions – Industrial Batteries

When designing a battery room, ventilation requirements need to be taken into consideration. Lead acid motive power batteries give off hydrogen gas and other fumes when recharging and for a period after the charge is complete. Proper ventilation in the battery charging area is extremely important.

• Calculating Hydrogen Concentration

• Calculating Room Volume

 A hydrogeninair hydrogeninair mixture mixture of !" or greater greater substantially increases the risk of an explosion. #he concentration of hydrogen should be kept below $" to provide a safety factor. %ydrogen gas is colorless and odorless. &t is also lighter than air and will disperse to the top of a building.

• Determining Ventilation Requirement

• Determining Fan Requirement

• Do You Need Forced Ventilation

• Hydrogen Gas Detector (HGD!"

#he information below is provided for reference only. 'tate and local codes may apply that supersede these guidelines. #he following is for general understanding only, and () &ndustrial )attery takes no responsibility for these guidelines.

#te$ !% Calculating Hydrogen Concentration

 A typical lead acid motive power battery will develop approximately .*$!+! cubic feet of hydrogen per cell at standard temperature and pressure. H & (C '  ' G ' )" * R !++ %-  /olume of hydrogen produced during recharge. 0-  1umber of cells in battery. 2-  Percentage of overcharge assumed during a recharge, use 3*". (-  /olume of hydrogen produced by one ampere hour of charge. 4se .*$!+! to get cubic feet. A-  5hour rated capacity of the battery in ampere hours. 6-  Assume gas is released during the last !- hours of an 7hour charge. E'am$le% 1umber cells per battery  3!  Ampere si8e of battery  !9* A.%. (H" & (,- ' ,+ ' .+!-/- ' -0+" * !++ %  +.:9:5 cubic feet per battery per hour  top

#te$ ,% Calculating Room Volume ;or a room with a flat roof volume is calculated W x L x % less the volume of chargers and other fixed ob / 6-  6oom cu. ft. /-  /entilation required $!!,*** x 5* > $!!.+=  9:@ 5:+.=5 cu. ft. per hour or ::9 0;?. #he ventilation system should be capable of extracting 9:,5:+.=5 cu.ft. per hour or ::9 0;?. top

#te$ 0% Do You Need Forced Ventilation &n theory the 9:5.:+ cu. ft.hr. only represents .**!" which is B $". #herefore forced ventilation would not be required for this example. %owever, the following should be considered before ruling out forced ventilationC &s the battery room closed in or openD &f closed in no natural ventilation may be possible. 'ince hydrogen gas rises are there areas in the ceiling where gas may collect in greater concentrations. #he above calculation represents worse case scenario assuming all batteries are gassing at the same time. #his is highly improbable. &f natural ventilation is sufficient in an open area forced ventilation should not be required. &f your calculations determine a percentage B$" hydrogen concentration, we recommend a %ydrogen (as Eetector for safe measure, part number HGD!.

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Hydrogen Gas Detector (HGD!" Operation 'hould the concentration of hydrogen gas in the air surrounding the sensor reach $" by volume, the F$" cautionF yellow LGE will light and the $" internal relay will close. 'hould the hydrogen gas concentration reach 3" by volume, the F3" warningF red LGE will flash and an 7* db alarm will soundH the $" relay will remain closed and, if a Eual6elay model, the 3" internal relay will close. Gither relay can activate a remote exhaust fan andor alarm.

Location %ydrogen, colorless and odorless, is the lightest of all gases and thus rises. #he detector, therefore, should be installed at the highest, draftfree location in the battery compartment or room where hydrogen gas would accumulate.

#he si8e of the area one detector will protect depends upon battery compartment room. #he detector measures the hydrogen gas in the air immediately surrounding the sensor. &f hydrogen gas might accumulate in several, unconnected areas in the compartment or room, individual detectors should be placed at each location. 2ptional AccessoriesC steel