Armstrong World Industries EHU-703, EHU-701 Tank DISASSEMBLY, CLEANING, and Electrode Replacement

Figure 34-1.

TANK DISASSEMBLY, CLEANING, AND ELECTRODE REPLACEMENT

MODELS EHU-703 AND 704, SINGLE AND THREE PHASE

1)Using a 7/16" wrench, disconnect the jumper wires from the steam generator.

2)Remove 24 metal clips by pushing gently on top of each clip with a screwdriver while cupping the clip with the other hand.

3)Lift the top half of the tank free of the bottom half and rest it on the electrodes. Use a ¾" wrench to loosen and remove the nuts from the six electrode studs.

4)Lift the top tank half from the electrodes. Remove the o-ring from the lower tank half o-ring channel and put it aside for re-use. On high voltage units, lift the barrier assembly out of the bottom tank half.

5)Clean the tank halves and the barrier assembly (Figure 35-1), if applicable, using a scraper, stiff bristle brush, and/or water spray. Rinse the unit with clear water. If necessary, the drain screen may be removed for cleaning by removing three screws and pushing up through the bottom tank connection with a screwdriver handle or other blunt object. The drain screen snaps back into place and is SECURED BY THE 3 SCREWS after cleaning. BOTH THE BARRIER ASSEMBLY AND

THE DRAIN SCREEN SHOULD BE REPLACED WITH NEW PARTS IF THEY ARE UNSERVICEABLE.

6)Install one electrode in the top tank half. Make sure the small o-ring is located at the bottom of the electrode stud. Push the electrode through one of the holes in the upper tank half. Slowly turn the electrode until it locks in place. Thread a nut, finger tight, onto the electrode stud. Repeat this process with the other five electrodes.

7)Turn the tank top half upright and rest it on the electrodes. Tighten the nuts on all the electrode

studs with a ¾" wrench, so they are just snug.

8)Install the electrode jumper wires to the studs at the top of the tank. Fasten one end of the jumper wire with a washer and a 1/4" hex nut, using a 7/16" wrench. There are three jumpers on a three-phase unit, and four jumpers on a single phase unit. On a single phase unit you should have only two loose ends ( Figure 34-1).

9)Install the o-ring in the bottom tank half o-ring channel.

A third hand or weight may be needed to hold one end of the o-ring in place while the other end is being installed.

10)Install the barrier assembly in the bottom tank half.

11)Lower the top tank half onto the bottom tank half. Line up the marks on the rim of the top and bottom tank halves to properly center the electrodes.

12)Look trough the top connection to make sure the o-ring is still in place.

13)Snap a metal clip over the flanges of the tank halves, midway between two alignment marks. Position another clip on the opposite side of the tank. Install all 24 clips in this manner.

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