Re-Chargeable Golf Cart Ventialtion and Area Classifications 1

[joerob]

I am currently reviewing a new golf clubhouse which includes a golf cart storage area in the basement. These golf carts are battery powered, and thus undergo re-charging. I know that during the re-charging process, hydrogen gas if given off. The storage area is equipped with a hydrogen gas monitoring system which turns on and exhaust system when the hydrogen level is detected as 20% of the lower explosion limit (lel), and shuts off power to all of the battery chargers and alarms if 40% lel is reached.

In addition to the above, I am considering incorporating the following measures. I feel that the cart storage area should be electrically classified as a Class I, Zone II hazardous location, since failure of the ventilation system could lead to the presence of dangerous level of hydrogen in the area. Additionally, I am considering de-energing all devices in the area if 40% lel is reached, not just the chargers. And finally, all equipment that is to remain operational in the event that 40% lel is reached should be installed in accordance with Class I Zone II requirements, such as the hydrogen detection system, emergency lighting, fire alarm, etc. The remainder of the equipment does not need to be classified for non hazardous areas as it would be de-energized.

Does anyone have any experience with golf cart storage area ventialation and classifications? Do the above measures of using Class I Zone II components seem like overkill since by shutting the battery chargers off, the release of additional hydrogen should be limited, or should all equipment in the area be of Class I Zone II type?

Comments are appreciated.

 

[dpc]

I have never seen a stationary battery room classified as Class I, Div 2. I can see your line of reasoning, but it does seem like overkill to me.

Let me point out the probably obvious fact that a basement is a really bad place for a battery charging system.

When designing battery rooms in the past, I have calculated the maximum outgassing of the batteries, the natural ventilation rates of the space and the allowable gas concentration levels. In every case, the answer was that it takes very little ventilation to keep hydrogen concentrations at safe levels. In many plants, we simply put batteries within a fenced area in an open area, instead of a small enclosed room and no forced ventilation was required.

My recommendation would be to simply run the ventilation system all the time and alarm it goes off for any reason. This will simplify the system and eliminate dependence on the H2 gas detection system which will probably be the least reliable part of the system.

Has a calculation be done that shows that explosive limit could be reached if ventilation system fails?

 

[mpparent]

I agree with dpc,

You may also want a backup fan, in case there is a failure of the primary fan. Hopefully, this should take care of your scenario.

 

[Codemaster]

I have designed charging rooms for golf carts. Contact Club Car (leading manufacturer of golf carts) and they have design guidelines. What you are proposing is overkill. Just interlock your exhaust and makeup air system and the hydrogen monitor to the charging equipment. If the exhaust system fails or the hydrogen alarm is set, then interrupt the charging process long before the atmosphere is combustible. The hardest part of my design was the eyewash station that was required, it needs to have tempered (water that is not too cold or too hot) water.