Lennox International Inc Gas Packaged Units Drip Leg Installation, Pressure Test Gas Piping

Drip Leg Installation
field provided
1/8 in. pressure tap
ground joint	unit
union
manual main
shut−off valve
	drip
	leg
	gas piping
	support

Figure 8

Pressure Test Gas Piping

When pressure testing gas lines, the gas valve must be disconnected and isolated. Gas valve can be damaged if subjected to more than 0.5 psig (14 inch w.c.). See figure 9. If test pressure is equal to or less than 0.5 psig (14 inch w.c.) shutoff the manual main shut-off valve before pressure testing to isolate unit from gas supply system.

Isolate Gas Valve To Pressure Test

Manual Main Shut−off Valve Will Not Hold Test Pressures in Excess of 0.5 PSIG (14 in. w.c.)

unit
gas valve	cap

Figure 9

NOTE − Codes may require that manual main shut off valve and union (furnished by installer) be installed in gas line external to unit. Union must be of the ground joint type.

!WARNING

Danger of explosion. Can cause injury or product or property damage. Do not use matches, candles, flame or other sources of ignition to check for leaks.

After gas piping is complete, carefully check all piping connections (factory and field) for gas leaks. Use soap solution or other preferred means.

NOTE − In case of emergency shutdown, shut off main manual gas valve and disconnect main power to unit. These devices should be properly labeled by installer.

The heating value of the gas may differ with locality. The value should be checked with the local gas utility.

NOTE − There may be a local gas utility requirement specifying a minimum diameter for gas piping. All units require a 1/2 inch pipe connection at the gas valve.

Gas piping recommendations:

CAUTION

If a flexible gas connector is required or allowed by the authority that has jurisdiction, black iron pipe shall be installed at the gas valve and must extend outside the cabinet. The flexible connector can then be added between the black iron pipe and the gas supply line.

1 − A drip leg and a ground joint union must be installed in the gas piping.

A ground joint union is recommended by the manifold/valve.

2 − When required by local codes, a manual shut-off valve may have to be installed outside of the unit.

3 − Use pipe thread sealing compound resistant to propane gas sparingly on male threads.

4 − The gas supply should be a separate line and installed in accordance with all safety codes. After the gas connections have been completed, open the main shut-off valve admitting normal gas pressure to the mains. Check all joints for leaks with soap solution or other material suitable for the purpose.

CAUTION

Some soaps used for leak detection are corrosive to certain metals. Carefully rinse piping thoroughly af- ter leak test has been completed. Do not use matches, candles, flame or other sources of ignition to check for gas leaks.

5 − The unit and its individual manual shut-off valve must be disconnected from the gas supply piping system during any pressure testing of that system at test pressures in excess of 1/2 PSIG (3.48kPa).

IMPORTANT

The unit must be isolated from the gas supply piping system by closing its individual manual shut−off valve during any pressure testing of the gas supply piping system at test pressures equal to or less than 1/2 psig. See figure 9.

The unit and its individual shut−off valve must be dis- connected from the gas supply piping system during any pressure testing of the system at test pressures greater than 1/2 psig.

6 − A 1/8 inch N.P.T. plugged tapping, accessible for test gage connections, must be installed immediately upstream of the gas supply connection to the furnace.

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