The Damper Leakage Test involves measuring the air volume leaking through the gaps in a damper's closed state, depending on its installation direction and shape. Through this test, the amount of air leakage during the closure state is determined, allowing for improvements to reduce leakage.
(※The compliance with CLASS classifications based on UL 555S, ensuring that the damper is appropriately manufactured to meet the leakage rating criteria, can also be confirmed.)
Guidance on Exhaust Damper Leakage Performance for Pressurized Smoke Control System
Related evidence
① Regulatory Basis: National Fire Safety Standard 501A Article 14 (Exhaust according to vertical duct)
Item 5, Subitem b: "The air volume of the exhaust fan shall be based on the criteria of Subitem a, and additional margin shall be added according to QN (Revised 2013.9.3)">
· After the revision of the National Fire Safety Standard on September 3, 2013, the inflow air discharge volume must confirm the performance of discharging more than the supplemental amount at the farthest exhaust damper from the exhaust fan.
· Global I&P has encouraged damper manufacturers and distributors to develop leakage performance. Over about a year, the leakage performance has been achieved to satisfy UL555S Class 2 requirements.
Please refer to the specifications and leakage performance of dampers when applying the performance of these products in the design and supervision site of the inflow air discharge fan and duct.
AL-1 average (damper size: 0.4x0.6=0.24m²)
| Dp[Pa] |
Leakage amount[1/s] |
Leakage amount[m³/min/m²] |
| 100 |
1.87 |
0.47 |
| 300 |
7.69 |
1.92 |
| 500 |
12.01 |
3.00 |
| 700 |
16.02 |
4.01 |
| 900 |
09.80 |
4.95 |
| 1100 |
20.62 |
5.15 |
| 1300 |
23.12 |
5.77 |
| 1500 |
24.59 |
6.15 |
AL-2 average (damper size : 0.4x0.6=0.24m²)
| Dp[Pa] |
Leakage amount[1/s] |
Leakage amount[m³/min/m²] |
| 100 |
10.11 |
2.53 |
| 300 |
12.87 |
3.22 |
| 500 |
16.41 |
4.10 |
| 700 |
20.80 |
5.20 |
| 900 |
21.32 |
5.30 |
| 1100 |
24.37 |
6.10 |
| 1300 |
25.47 |
6.37 |
| 1500 |
28.26 |
7.06 |
Damper leak rating of "UL555s"
| Classification |
Leakage [m³/min/m²] |
| 250 Pa |
1,000 Pa |
2,000 Pa |
3,000 Pa |
| Ⅰ |
1.23 |
2.45 |
3.38 |
4.29 |
| Ⅱ |
3.06 |
6.12 |
8.57 |
10.72 |
| Ⅲ |
12.25 |
24.49 |
34.29 |
42.86 |
| Ⅳ |
18.37 |
36.73 |
51.43 |
64.29 |
Test result
① AL-1 damper "UL555s" satisfies the damper leakage class CLASS Ⅱ.
② AL-2 damper "UL555s" satisfies the damper leakage class CLASS Ⅱ.
