Armstrong World Industries EHU-700 Series User Manual

This procedure is intended as a guide only for the chemical cleaning of the generator in all EHU mod-
els. Read and follow label directions on any cleaning product. Check local codes before disposing of
chemicals.

Muriatic acid can cause severe chemical burns if not handled properly. Wear rubber gloves

and eye protection when using. Read and follow carefully the safety procedures on the package.

1)   Obtain several gallons of muriatic acid. Muriatic acid is the name for commercial hydrochloric acid.

It is available in most hardware, pool chemical, or farm supply outlets.

2)   Remove the tank, following the "Tank Removal" directions in this manual.

3)   Let the steam generator tank cool after removal from the EHU unit.

4)   Split the tank, referring to the directions on page 33 of this manual, and examine the inside of 

the tank and the electrodes.

a. If the tank is black or dark brown, the electrodes may have disintegrated and chemical cleaning

may not be effective. The tank can be cleaned with the following process, but the electrodes 
may need to be replaced.

b. If tank and electrodes have a white/tan/grey mineral accumulations and/or the tank is partially 

filled with loose lime accumulations, proceed with chemical cleaning.

5)   Empty any loose deposits from the bottom tank half. Both tank halves and the barrier assembly, if

present, can be cleaned using a scraper, a stiff bristle brush, and water spray as required. Refer
to the directions on page 33 of this manual for details on removing the drain screen for further 
cleaning, if necessary.

6)   Remove the electrodes from the upper tank half, following the directions on page 33 of this 

manual. Loose and/or soft deposits should be scraped from the exterior of the electrodes before 
chemical cleaning.

7)   Prepare the chemical cleaning solution as per manufacturer's recommendations and fill a plastic 

bucket to a sufficient level to soak the electrodes. Be certain not to submerge the electrodes 
beyond the level of the screen.

8)   Let the cleaning action take place for 15 minutes. Remove the electrodes from the bucket and 

rinse them thoroughly with a clean water spray.

9)   Observe the electrodes to determine if another treatment is necessary.

10) It is not necessary for the electrodes to be cleaned down to bare metal. Removal of major 

accumulations is the only requirement.

11) Helpful Hints:

* Check the drain valve for proper operation & good flow when the tank is drained prior to 

removal.

* With the tank removed, inspect the drain adaptor and hose from adaptor to drain valve to 

ensure that it is free from deposits which may interfere with proper drainage.

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