System Sensor DH100ACDCP Inlet tubes required for different duct widths, Outside Duct Width

Figure 3. Installation of foam gaskets over sampling tube bushings:

SCREW HOLES FOR

ATTACHING HOUSING

TO DUCT WORK.

A78-2045-00

[5.4] Sampling Tube Installation for Ducts Greater Than 11⁄2 Feet Wide

The sampling tube is identified by a series of air inlet holes on the tube. A plastic tube is included for ducts up to 18″ in width. All other lengths must be purchased separately. Order the correct length, as specified in Table 1, for width of the duct where it will be installed. The exhaust tube is molded onto the base of the duct housing, and the A2440-00 Exhaust Tube Extension is available as an accessory in those cases where the molded exhaust port does not extend at least 2 inches into the duct.

The inlet tube is always installed with the air inlet holes facing into the air flow. To assist proper installation, the tube’s mounting flange is marked with arrows. Make sure the inlet tube is mounted so that the arrows point into the air flow (see Figure 4). Figure 5 shows the various combi- nations of tube mounting configurations with respect to air flow. Mounting the detector housing in a vertical orienta- tion is acceptable, provided that the air flows directly into the sampling tube holes as indicated in Figure 4.

Table 1. Inlet tubes required for different duct widths:

Outside Duct Width		Inlet Tube Required
1	to 2 ft.	ST-1.5
2	to 4 ft.	ST-3
4	to 8 ft.	ST-5
8 to 12 ft.		ST-10

[5.4.1] Installation For Ducts Greater Than 11⁄2 Feet But Less Than 8 Feet Wide

1.If the tube is longer than the width of the air duct, drill a 3⁄4″ hole in the duct opposite the hole already cut for the inlet tube. Make sure the hole is 1″ to 2″ below the inlet hole on the opposite side of the duct to allow moisture drainage away from the detector. If the tube is shorter than the width of the air duct, install the end plug into the inlet tube as shown in Figure 4. Sampling tubes over 3 ft. long must be supported at the end opposite the duct smoke detector.

2.Slide the tube into the housing bushing that meets the air flow first. Position the tube so that the arrows point into the air flow.

3.Secure the tube flange to the housing bushing with two #6 self-tapping screws.

4.For tubes longer than the width of the air duct, the tube should extend out of the opposite side of the duct. If there are more than 2 holes in the section of the tube extending out of the duct, select a different length using Table 1. Otherwise, trim the end of the tube protruding through the duct so that 1″ to 2″ of the tube extend out- side the duct. Plug this end with the end plug and tape closed any holes in the protruding section of the tube. Be sure to seal the duct where the tube protrudes.

Figure 4. Air duct detector inlet sampling tube:

FLANGE	AIR HOLES	INLET
		TUBE
		END
		PLUG

ARROWS	AIR FLOW DIRECTION
MUST FACE
INTO AIR FLOW
	A78-2047-00

Figure 5. Tube mounting configurations with varying air flow direction:

	DOTS INDICATE POSITION OF
	SAMPLING TUBE HOLES
AIR FLOW			AIR FLOW
			DIRECTION
DIRECTION
DETECTOR			DETECTOR
HOUSING			HOUSING
	A.		B.
INLET	EXHAUST	EXHAUST	INLET
TUBE	TUBE	TUBE	TUBE
	HORIZONTAL MOUNTING OF HOUSING
	EXHAUST
		TUBE	DETECTOR
			HOUSING
	EXHAUST
AIR FLOW	TUBE		AIR FLOW
DIRECTION			DIRECTION
	INLET	INLET
DETECTOR	TUBE	TUBE	D.
HOUSING	C.

VERTICAL MOUNTING OF HOUSING

NOTE: Only metal sampling tubes may be used on ori- entations C and D.

WARNING

In no case should more than 2 air inlet holes be cut off the tube. There must be a minimum of 10 holes in the tube exposed to the air stream.

[5.4.2] Installation For Ducts More Than 8 Feet Wide

NOTE: To install inlet tubes in ducts more than 8 feet wide, work must be performed inside the air duct. Sampling of air in ducts wider than 8 feet is accom- plished by using the ST-10 inlet sampling tube. If the tube is shorter than the width of the air duct, install the end plug into the inlet tube as shown in Figure 4 and support the end opposite the duct smoke detector.

D100-68-00 3 I56-1147-12R