Trichloroethane, stainless steel

Coupons of Type 304 stainless steel were prepared by mechanical abrasion and rinsed with methanol. Each sample was analyzed by XPS prior to treatment to ensure that no detectable casually-introduced chlorine was present. Two separate series of laboratory experiments were done one series (a) followed the effects of short-term contact between chlorocarbon and the alloy surface, a second series (b) investigated the effects of prolonged vapor and liquid contact with the alloy in a glass refluxer. In series (a) the clean alloy surface was swabbed using trichloroethane-soaked tissue and immediately inserted into the vacuum chamber of an XPS spectrometer for analysis. After analysis, the same coupon was exposed to the atmosphere for periods of 72 and 336 hours... 

Three Cl 2p photoelectron spectra for a 304 stainless steel surface im-after rinsing with trichloroethane (a), the same surface after atmospheric for 50 h (b), and the surface of 304 stainless steel exposed to trichloroethane vapor for 50 h and to atmosphere for 3000 h (c). 

For each series of experiments, the same stainless steel coupon (4 cm X 3.5 cm X 0.1 cm) was precleaned, coated with the test contaminant, and then placed in the autoclave for testing. For precleaning, the coupon was either washed first in a chloroform bath, rinsed with acetone, and then dipped in an acetone bath or immersed in a 1,1,1-trichloroethane bath and wiped with a tissue to remove any residue. After precleaning, the coupon was weighed to determine when the mass of the coupon was within 0.1 mg of its original weight. This was set as the standard for perfect cleanness of the coupon. 

A short description of the methods used for analysis of 1,1,1-trichloroethane in environmental samples is presented in Table 6-2. An extensive list of methods for analysis of 1,1,1-trichloroethane in environmental samples can be compiled from the literature. Two methods are commonly used for collection of 1.1.1-trichloroethane and other volatile organics in ambient and occupational air. One method uses adsorbents to trap and concentrate organics in air. and the other method uses passive stainless steel canisters (SUMMA canisters). The advantage of SUMMA canisters is that sample breakthrough does not occur with this method as it may occur with adsorbent tubes (Hsu et al. 

The pruity of halogenated solvents is determined using a thermal conductivity or flame ionization detector, a column made from 3.2 mm stainless tubing packed with 30 wt% silicone fluid on 80-100 mesh diatomaceous earth or using capillary colurtm. Admixtures in 1,1,1 -trichloroethane are determined using a thermal conductivity or hydrogen flame detector. Column from copper or stainless steel is packed with Chromosorb W HP with 20% polydimethylsiloxane. ... 

The first series of products developed and commercialized were the solvent processable resists called RISTON I. A 24" wide conveyorized spray developer was fabricated that used 1,1,1-trichloroethane (methyl chloroform) as the developing solvent. After development, the PWB panel was then ready for etching or electroplating. Following that, it was necessary to strip away the polymerized resist. Methylene chloride or azeotropes with methanol were the iiutial stripper chemistries and DuPont fabricated 24" conveyorized equipment to perform that operation. The developer and stripper equipment both fabricated from stainless steel, required in-line solvent stills that would continuously feed a fresh supply of clean distillate solvent through a series of spray chambers and in a counter flow direction to that in which the boards were traveling. Smaller fabricators often stripped using a series of dip tanks. 

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