What is the maximum discharge time allowed for an HFC 227ea system?

The time to discharge 95 percent of the required agent mass shall not exceed 10 seconds for total flooding systems (Clause 6.6.3.2).

Can HFC 227ea systems be installed in rooms that are normally occupied?

Yes, but the design concentration must not exceed the No Observed Adverse Effect Level (NOAEL), which is 9.0% by volume (Clause 5.1.2.2).

How often should the extinguishing agent cylinders be weighed?

The agent quantity in the containers must be checked at least semiannually. If a container shows a loss of agent more than 5 percent, it must be refilled or replaced (Clause 11.2).

What is the formula for calculating the required amount of HFC 227ea?

The agent weight (W) is calculated using the formula W = (V/s) * [C / (100-C)], where V is the net volume, s is the agent's specific volume, and C is the design concentration (Clause 6.5.2).

IS 15517

: 2004

Gaseous Fire Extinguishing Systems - HFC 227ea (Hepta Fluoro Propane) Extinguishing Systems

CurrentFrequently UsedCode of PracticeBIMFire Safety · Fire Fighting

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This standard provides requirements for the design, installation, testing, and maintenance of HFC 227ea gaseous fire extinguishing systems. These 'clean agent' systems are used for total flooding of enclosures containing high-value assets where water damage is unacceptable, such as data centers and control rooms. The code focuses on calculating agent quantity, ensuring personnel safety, and verifying system and room integrity.

Gaseous Fire Extinguishing Systems - HFC 227ea (Hepta Fluoro Propane) Extinguishing Systems

Quick Reference Values

No Observed Adverse Effect Level (NOAEL)9.0% by volume

Lowest Observed Adverse Effect Level (LOAEL)10.5% by volume

Minimum Design Concentration for Class A (Surface Fire)7.5% by volume

Maximum Discharge Time10 seconds

Minimum Soaking Time for Class A hazards10 minutes

Semiannual Inspection - Max Agent Loss5% by weight

Semiannual Inspection - Max Pressure Loss10%

Key Formulas

W = (V/s) * [C / (100 - C)] — Formula for calculating the weight (W) of clean agent required.

Practical Notes

Room integrity is paramount for system success. A door fan test (as per Annex E) is crucial to verify that the enclosure can hold the agent concentration for the required 10-minute soaking time.

For normally occupied areas, the design concentration MUST be kept below the NOAEL of 9.0% to ensure personnel safety.

HFC 227ea thermally decomposes into hazardous substances like Hydrogen Fluoride (HF) when exposed to fire. The system must discharge within 10 seconds to extinguish the fire quickly and minimize the production of these by-products.