Understanding Fire Hydrant Pressure: Why Is It Set at 7 kg/cm²?

Hydrant Pressure Explanation

Please describe why the hydrant pressure is 7 kg/cm².

Regards,
Subodh

Normally, at the battery limit of the plant (which includes structures, columns, and vessels that are nearly 50 meters high or as per the design need), the pressure of the fire hydrant system will be 5 Kg/cm². In order to maintain that, considering the pressure losses and line losses, it is normal to maintain the fire hydrant pressure at 7 Kg/cm². Anything more than that is energy waste. Anything less than that will create problems during a fire crisis. Hope this clarifies. If you need detailed clarification, please consult a piping and HSE expert on this.

Regards

It is as per the standards and depends upon the type of occupancy. It may vary from 7 kg/cm² to 12 kg/cm² depending on the type of occupancy.

With reference to the above I hv few questions mentioned below
. Pressure standard decided by NFPA body or any other
. 7kg/cm² to 12/cm² means how much litter water will come per min.

Hydrant mains should be tested with the pump delivering at its maximum pressure with all the hydrant outlets closed. Thereafter, at least three adjacent hydrants should be opened to ensure that the hydrant yields a minimum output of 1125 litres per minute at a minimum pressure of 5.25 kgf/cm2 as per IS13039:1991 (External hydrant systems provision and maintenance code of practice).

Regards,
PARAG BANE
Safety & Environment (Birla Carbon)

Hi Parag sir,

Thank you very much for your quick response. Now, out of curiosity, how is the calculation done? If it's 7 kg/cm2, then how much water would come out per minute? Could you please explain the way to calculate it? Thank you.

Dear Ashok,

For calculation, it depends on the number of hydrant points, pump capacity, head, length of the line, etc.

Thank you.

Respected sir,

I just want to know the lpm if it's between 7 to 12 kg/cm2 and the basic way to calculate it. Sir, please help me to get this answer. It's really important for me to know, please.

Thanks and regards,
Ashok K