The boiler is initially half-filled with feedwater to partially dilute the treatment chemicals which must be added. The treatment chemicals are then added to bring the boiler water conditions to near the upper limits. The necessary amounts of treat-ment chemicals are weighed, dissolved in feed-water, and injected into the boiler.

WARNING: TSP solutions are corrosive and cause burns to skin, eyes, and body tissues. Affected personnel should flush skin with cold water. If TSP or its solutions enter the eyes, flush with cold water and obtain immediate medical attention.

TSP is added to bring the alkalinity to 2.0 equivalents per million (epm) (2.0 meq/L) and to provide some of the needed phosphate. DSP is added to bring the phosphate to 300 parts per million (ppm) (300 mg/L) and not to the upper limit of 400 ppm (400 mg/L). In order to deter-mine the amount of chemicals needed, the volume of water requiring chemical treatment must be known. This information is sometimes available in the instruction manual for the boiler. If the weight of water at normal steaming level while steaming is given, divide the weight in pounds by 8.33 to determine volume in gallons. If the boiler weight data gives only the dry weight and the wet weight of the boiler, determine the boiler water chemical treatment volume as follows:

1. Subtract the boiler dry weight from the boiler wet weight to obtain a weight of cold water in the boiler.

2. Divide the weight of cold boiler water in pounds by 9.30 for boilers operating at 125 pounds per square inch (psi) or 8.87 for boilers operating at 35 psi to obtain the boiler water volume, in gallons, for chemical treatment. This volume times the initial chemical treatment factors (ounces per gallon) given in table 7-2 deter-mines the ounces of TSP and DSP required. Enter the volume to the nearest gallon and the calculated dosage to the nearest one-half ounce in the appropriate columns.

Table 7-2.Natural Circulation Auxiliary Boiler Water Initial Dosage

Initial dosages for several of the auxiliary boilers are given in table 7-3. The volumes listed are for the following vessels:

Weigh the necessary amount of chemicals and place both in the 10-liter safety dispensing bottle.

The safety dispensing bottle should be marked and used For boiler water treatment chemicals only. Add cold feedwater, cap the bottle and spout, then shake to dissolve. Inject the solution into the boiler.

Auxiliary boilers are equipped with a chemical injection system on a bypass of the feedwater line. One treatment system schematic and general procedures for auxiliary boilers are presented in figure 7-3. When you are operating an injection system, slightly overfill the tank to bleed air out of it. The over-filling must be minimal; otherwise an excessive amount of treatment will be discharged to the bilge. In addition, injection must continue for at least 10 minutes to ensure that all of the treatment is flushed into the boiler. Upon completion of the chemical addition, finish filling the boiler to the lightoff level, or if the boiler has been over-filled, drain until the proper water level is reached. A boiler water sample obtained from a

Table 7-3.Chemical Weights For Freshly Filling Some Auxiliary Boilers

WARNING: Protective clothing shall be worn while pouring concentrated chemicals into chemical injection tank and while topping off.

GENERAL PROCEDURE FOR ADDING CHEMICAL (ASSUMING VALVES SET FOR NORMAL OPERATION, i.e., VALVES 1,2,3 OPEN AND VALVES 4,5,6,7,8 CLOSED).

1. Slowly open valves 7 (drain), 6 (overflow/vent), and then 5 (funnel fill).

2. Close valve 7.

3. Charge the injection tank with treatment chemicals already in solution through the funnel.

4. Top off tank with feedwater obtained in bucket until an overflow just starts.

5. Close valves 5 and 6.

6. Open valves 4 and 8.

7. Close valve 1.

8. Maintain a flow of water for 10 minutes to wash out the injection tank.

INJECTION TANK SECURING PROCEDURE

1. Open valve 1.

2. Close valves 4 and 8.

3. Drain injection tank by first slowly opening valve 7 and then valve 6.

4. Close valves 6 and 7.

Figure 7-3.Auxiliary Boiler Chemical Injection Procedure.

freshly filled, chemically treated boiler, prior to light off, is not representative and is therefore meaningless. The freshly filled and treated boiler shall be steamed immediately but not later than 24 hours after being filled. Preferably, the boiler should not be filled unless it is expected to be fired within 24 hours. If the boiler can-not be steamed within 24 hours, it should be placed under dry layup in accordance with chap-ter 221, Boilers, Naval Ships Technical Manual.