DREW SAF ACID (Descaling Compound)

DREW SAF ACID (Descaling Compound)

SAF ACID (Descaling Compound)

SAF-ACID 安全酸(水垢清洁剂)




SAF-ACID descaling compound is a special blend of sulfamic acid, wetting agent and color indicator. The wetting agent enhances the action of the sulfamic acid in removing deposits by its surface-active cleaning properties. The color indicatorprovides a simple means for determining whether the strength of the SAF-ACID solution is adequate for effective, efficient cleaning.



Concentrated liquid

Reduces cleaning time

Cost effective

Does not require equipment disassembly for cleaning

Contains a corrosion inhibitor

Minimizes metal attack during cleaning

Can be used in most shipboard systems

Contains a wetting agent

Penetrates light, organic film

Quick removal of scale

Contains a color indicator

Does not require special test apparatus

Easy determination of solution strength

Free-flowing powdered acid

Easy to store and mix

'Application and Use

SAF-ACID descaling compound is recommended for removing mineral scale deposits from evaporators, heat exchanger heat transfer surfaces and boilers. It is also effective in removing iron deposits when used in combination with salt. SAF-ACID descaling compound is effective in removing shell growth from seawater heat exchangers. Before using SAF-ACID descaling compound, if there is organic matter (oil) in the deposits, the equipment should be cleaned with HDE-777 heavy-duty emulsifier,LAC liquid alkaline cleaner or EDGE heavy-duty cleaner. If the organic material is baked on, it may require an initial cleaning with DREWFRESH 2000 heavy-duty cleaner SAF-ACID descaling compound must be dissolved in fresh water before adding to cleaning equipment. When dissolved, SAF-ACID descaling compound strength is monitored by a built-in color indicator. A gold color indicates SAF-ACID solution is the appropriate strength for descaling. As scale is dissolved and the acid strength becomes exhausted, the solution turns from gold to green. When this occurs, the solution is no longer sufficiently acidic to efficiently dissolve scale. The cleaning solution can be brought back to strength by the addition of approximately 25% of the initial dose of SAF-ACID descaling compound. The additional SAF-ACID descaling compound should turn the solution gold again while maintaining the cleaning solution temperature at 60-70° C (140-160° F).

When equipment is very heavily scaled and large amounts of SAF-ACID descaling compound are required, the solution may become saturated and will remain gold in color because no additional scale can be dissolved. To avoid this, not more than two subsequent acid charges should be added. If, after the second addition of SAF-ACID descaling compound the equipment is not clean, properly discard the solution and repeat the cleaning procedure with a fresh acid solution. After cleaning with SAF-ACID descaling compound, drain and flush with fresh water and rinse with a 1% solution of GC concentrated alkaline liquid to neutralize any acid remaining on heat transfer surfaces.

Important Information and Precautions


• Do not allow acid solution to remain in equipment for more than 24 hours.

• As with all acid cleaning, be sure to remove zinc plates and rods or other sacrificial anodes before cleaning.

• The acid cleaning process may generate flammable/hazardous gas, including hydrogen. Do not perform hot work when acid is in circulation. • Always make sure that equipment has sufficient ventilation to prevent the accumulation of gases. For boiler cleaning:

• Do not acid clean a boiler with SAF-ACID descaling compound when deposits contain significant amounts of copper or a high percentage of silica.

• Never fire the boiler while containing an acid solution.

• Vent to the outside. For evaporator/heat exchanger cleaning:

• Do not add sodium chloride (ordinary salt) to the acid solution for removing iron oxide deposits if the equipment is made of stainless steel.

NOTE: Care should be taken to follow local treatment and disposal regulations with all waste water.

Equipment Required

Proper planning is essential to acid cleaning with SAF-ACID descaling compound.

The following items are required:

1. The ideal equipment for this cleaning is the Chemical Cleaning Circulating Unit.

2. Vent pipe to carry any gases released during the cleaning to the outside.

3. Protective clothing for personnel performing the acid cleaning. This includes goggles or splash shield, rubber gloves and a rubber apron.

Cleaning Compounds Required and Dosing Chart

Dosing Quantity Calculation

Capacity of equipment To obtain required dosage of SAF-ACID figured by the following: compound (10% concentration), multiply capacity of equipment by the following:

Kgs. Lbs.

Cubic meters (metric tons) 100 220

The dosage of GCTM concentrated alkaline liquid required for neutralization is listed below:

Capacity of equipment To obtain a 1% solution of GC liquid, figured by the following: multiply capacity of equipment in tons by the following:


Cubic meters (metric tons) 10

If deposits contain iron oxide, add sodium chloride (ordinary salt) to the acid solution. The amount of salt needed is equal to half the amount of SAF-ACID descaling compound used. Remember, if the equipment is stainless steel, do not add salt.

Pretesting for Leaks

Before cleaning begins, equipment should be checked for leaks. Prepare the chemical cleaning equipment, fill the mix tank with water and turn on the circulation pump to fill the equipment to be cleaned. Maintain the level of water in the mix tank at half full. Circulate the water by means of the pump and check to be certain there are no leaks in the piping and that the equipment is functioning. If there are no leaks in the system, proceed with cleaning.

Cleaning Procedure

1. Boilers

Install vent piping from a top opening in the boiler to the outside.

Disconnect the bottom blowdown piping and install a “tee.” Run a line from one end of the tee to waste water collection tank. Install a shut-off valve in this line. Run a line from the circulating pump discharge to the other end of the tee. Run a line from the bottom of the mix tank to the suction side of the circulating pump. Run another line from the top of the boiler to the top of the mix tank. Set all valves properly. Fill the boiler to the bottom of the gauge glass with water as well as the mix tank, pump and hoses. Fire the boiler using a low fire until the temperature of the water reaches 65° C (150° F). Start the circulating pump and regulate the flow of solution so that the pump removes water from the mix tank at the same rate it is added. Circulation will be from the bottom to the top of the boiler. Refer to Diagram 1 for circulation through the boiler.

Slowly add the proper amount of SAF-ACID descaling compound to the mix tank. A 10% by weight solution will be required. Refer to the dosage chart to determine the required amount of SAF-ACID compound to add to the mix tank to make a 10% by weight solution relative to the size of the boiler. When the acid cleaning solution is exhausted, it turns from a gold to green color. If this occurs, add approximately 25% of the initial dose of SAF-ACID descaling compound. Cleaning is complete when the strength of SAF-ACID descaling compound holds steady for at least two (2) hours as indicated by a steady gold color. After two (2) hours, stop the acid pump, drain and flush the boiler. After the boiler is flushed, fill the boiler with water and add the required amount of GCTM concentrated alkaline liquid to obtain a 1% solution. Refer to the dosage chart to determine the required amount of GC liquid to make a 1% solution. This will neutralize any acid remaining in the equipment. Circulate the neutralizing solution for a minimum of two (2) hours. Once neutralized, drain and inspect the boiler. If necessary, flush with a high-pressure hose to remove any loose matter. If satisfactory, return the boiler to normal operating condition by disconnecting the vent pipe and tee and reconnecting the blowdown line, etc. If not returned to service, the boiler must be passivated. Check with your local Drew Marine representative for passivation procedures.

2. Evaporators/Heat Exchangers

Add SAF-ACID™ descaling compound slowly to the tank of water, stirring if necessary until the desired quantity of acid is dissolved. Refer to the dosage chart for the amount of acid required. Circulate the acid cleaning solution at a temperature of 60-70° C (140-160° F). The solution may be heated by either the introduction of steam or the use of an immersion heater. If the equipment is badly scaled, it may be necessary to discard the cleaning solution and make a fresh batch. Cleaning is complete when the SAF-ACID strength holds constant for at least half an hour as indicated by a steady gold color. Cleaning is generally accomplished in 2-6 hours. Drain the cleaning solution and flush the system. Refill with water and add the required amount of GC concentrated alkaline liquid. Refer to the dosage chart for making a 1% neutralizing rinse solution. Circulate for 1/2 to 1-1/2 hours, then drain the system. Inspect the system and return to service.

Typical Physical Properties

Appearance: Green, granular powder

Solubility in Water: 20% at 16° C (6° F)

pH of 10% Solution: 0.7

Flash Point: N/A

NOTE: Always wear the appropriate safety equipment when using this product.


SAF-ACID descaling compound is available in 25-kg containers.

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