DISCUSSION WITH
THE SAFETY OF MINES RESEARCH
BOARD – BUXTON
Discussions on the use of Diesel engines underground in Great Britain were held with Messrs. A.H. Wynn, F.J. Hartley, and C.W.S. Grice, at the Sheffield office of the SMRB. It was mentioned in these discussions that there are approximately 200 locomotives in underground service at the present time. The requirements state that the undiluted exhaust of these locomotives shall contain not more than .2% CO and that the CO concentration in the main body of the ventilating air must be less than 0.005%. At present the SMRB is working on the draft of detailed specifications for flame-proof Diesel locomotives. These specifications would correspond to those outlined by the U.S. Bureau of Mines in Schedule 22, and I was informed that considerable weight is being given to our Schedule 22 in the formulation of the British requirements. I pointed out to the representatives of the SMRB that we had hoped to learn from them some of their experiences in connection with the approval of Diesel mine locomotives to assist us in connection with the approval from them some of their experiences in connection with the approval of Diesel mine locomotives to assist us in revisions of Schedule 22 that seemed necessary. I was informed that our work on exhaust gases has been much more extensive and thorough than work done by the SMRB. Similarly, our work on the determination of conditions under which Diesel engines can ignite flammable atmospheres has been much more extensive then theirs. Following these preliminary discussions in Sheffield, I went to Buxton where I met Dr. Sheperd and Messrs, Robinson, Titman, and Hayne. Further discussion with these individuals corroborated what had been outlined in Sheffield. Mr. Hayne is in charge of the testing of flame-proof equipment and has, therefore, tested all of the scrubbers and intake systems intended for use on Diesel mine locomotives. Scrubbers are tested with pentane air mixtures. In general, four tests are made on each unit. The unit is approved if it fails to ignite a surrounding atmosphere in these four tests, even though visible flames are emitted from the protective device. In discussing the question of permissibility requirements and the necessity for cooling the exhaust gases as they left the manifold to maintain engine surface temperatures below 400°F., it was mentioned that difficulties had been encountered in Great Britain as a result of excess surface temperatures. In one installation, a connection from the exhaust manifold to the scrubber had been changed on a locomotive and it led to a local overheating of the scrubber and excessive surface temperatures which had resulted in a fire, starting from combustible material accumulated in the vicinity of a hot spot on the scrubber. It was my impression that several fires traceable to hot engine surfaces had been encountered in actual underground operations. These experiences emphasize the importance of keeping surface temperature below the permissible maximum temperature of 400°F.