Preoperational cleaning

Unlike process- or water-side deposits, the types of deposits in original equipment are easily categorized. Preoperational cleaning should include consideration of the degree of cleanliness required and the material of construction. Areas where preoperational cleaning is used include  

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Preoperational cleaning (POC) of new boilers is always required but is often a last-minute item and not given the necessary attention it deserves, which may lead to operational problems down the line. A POC work program is needed to provide for ... 

Chemically cleaning new boilers before they are put into service is termed preoperational cleaning (POC), precommission cleaning, (PCC), or sometimes simply a boil-out. 

O-PO4 is often used in combined preoperational cleaning and passivation programs and acts, in the presence of oxygen, to promote passivity on iron surfaces, changing it from an active state to a passive state by forming a barrier to corrosive ions (although the starting material may actually be P-PO4). 

Providing a clean metal surface (by preoperational cleaning)... 

Most usually, a preoperational cleaning (POC) process/passivation program uses a chemical cleaner formulation based on a polyphosphate such as SHMP or STTP, together with various dispersants and surfactants. Where polyphosphate is not permitted to be discharged to sewer, silicates can often be used. Formulations may also include NaEDTA and sometimes specific corrosion inhibitors such as tolyltriazole (TTA). 

Both a full preoperational cleaning process and a short-cycle passivation process should be carried out with minimal load on the system to limit evaporation across the tower and the concentration of dissolved solids in the system water. However, some load may be necessary to raise the temperature of the circulating water. 

See also Chapter 9, Section 4, and the notes on Process Contamination in Section 10.8.28). Techniques for the on-line cleaning of open recirculating cooling water systems are often similar to those for preoperational cleaning in that generally there is a two-stage approach ... 

This area has to be preoperationally cleaned to remove particulates and iron oxides. In addition to being a dehydrogeneration catalyst, iron is also an oxidation catalyst and promotes the conversion of CO to CO2 in the regenerator. This conversion is... 

Preoperational cleaning is mandatory in such cases. After cleaning, the lines should be blown dry, using oil-free nitrogen or air. 

Preoperative prophylaxis For clean-contaminated or potentially contaminated surgical procedures, administer 1.5 g IV prior to surgery (approximately V2 to 1 hour before). Thereafter, give 750 mg IV or IM every 8 hours when the procedure is prolonged. 

Rotter, M.L. et al., A comparison of the effects of preoperative whole-body bathing with detergent alone and with detergent containing chlorhexidine glucontate on the frequency of wound infections after clean surgery. J. Hosp. Infect. 11, 310-320, 1988. 

Benzalkonium chloride is a mixture of alkylbenzyldimethylammonium chlorides of the general formula [CgH5CH2N(CH3)2R]Cl, where R represents a mixture of the alkyls from C8Hi7 to C18H37. In dilute solution (1 in 1000 to 1 in 2000) it may be used for the preoperative disinfection of skin and mucous membranes, for application to burns and wounds, and for cleaning polythene and nylon tubing and catheters. Benzalkonium chloride is also used as a preservative for eye-drops and as a permitted vehicle for the preparation of certain eye-drops. 

The antiseptic preoperative shower/bedbath is performed the night before the operation with the designated antiseptic. A clean washcloth or disposable sponge is used each time to apply the antiseptic. The intended incisional site is cleaned with extra strokes, being careful not to denude the skin resulting in case cancelation. Rinse the antiseptic off. Thoroughly towel dry before donning clean bedtime clothes. 

Quaternary ammonium compounds are cationic detergents. They are used as preservatives in cosmetic and medical topical products and also as a disinfectant for the skin (for instance, preoperative skin cleaning). It is also known as an algaecide (wood preservative, some marine paints). Patch-test concentrations range from 0.01% to 0.1% aqua. Patch testing with 0.1% aqua easily provokes irritant reactions true allergic responses are also obtained with 0.01% aqua. Crossreactions between the quaternary ammonium compounds are frequently seen. 

There are four types of equipment cleaning preoperational, chemical, mechanical, and on-line. These must he evaluated for each job in order to select the most cost-effective. To make a sound evaluation, the deposit to be removed should be thoroughly characterized. 

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