There are generally two schemes for the interlocking stop smoke exhaust system:

Scheme 1: The trigger signal is derived from the fire valve operating mechanism. The schematic diagram can be found in Figure 3. In the figure below, KH leads from the normally open smoke exhaust fire valve at the inlet of the smoke exhaust machine, and the linkage line can be connected from the fire valve to the control box of the supplementary fan by using the ZBN-KVV-450/750-2x1.5 control cable. The X1:9 and X1:10 terminals of the fan control box should not be shorted. HVAC professionals should choose an operating mechanism that can provide 3 pairs of normally open signals to meet the practice of Scheme 1, and the general operating mechanism only provides 2 pairs of normally open signals, so special attention is required when ordering.

Scheme 2: Use the normally closed auxiliary contact of the intermediate relay KA7 in the smoke exhaust fan control box as the trigger signal. Cancel the TC control transformer and KA7 in the fan control box. The linkage line can be connected from the smoke exhaust fan control box to the supplementary fan control box by ZBN-KVV-0.6/1.0-2x1.5 control cable. Note that the KA7 intermediate relay in the control box of the smoke exhaust fan should use 2 pairs of normally closed contacts.

summary

■ In scheme 1, the physical switch signal of the fire valve is directly used as the trigger signal to ensure that the smoke exhaust system is not affected by other factors and improves the reliability of the system. It is consistent with the concept advocated by GB 51251-2017 in the technical regulations on building smoke prevention and exhaust. However, when ordering smoke exhaust fire valves, it is necessary to add switch contacts and modify the product, which is difficult to implement.

■ In the second scheme, the intermediate relay is used to expand the signal, and the production control box manufacturer needs to be reminded to select two pairs of normally closed contacts of the intermediate relay KA7. This solution has no requirements for fire valve equipment, and only minor changes to the relay can be made. The disadvantage is that if the intermediate relay fails, it will affect the shutdown of the supplementary fan; The reliability is not as good as option 1.

The author suggests: Option 2 can be adopted in the near future, and after the fire valve manufacturer modifies the product, it is recommended to adopt option 1, which is more reliable.

In addition, when applying the schematic diagram of the atlas of "16D303-2 Commonly Used Fan Control Circuit Diagram" during the design process, it should be noted that the two terminals of X1:9 and X1:10 should not be shorted (see Note 3 on page 23 of the atlas), and it is recommended to mark it in the system diagram.