I did my apprenticeship as an Aircraft Toolmaker and ended up as a self employed compressed air engineer. I am also a pressure vessel examiner and carry out work for the HSE and some insurance companies. Whilst on a course with BCAS in London an example of how dangerous compressed gasses can be. This includes compressed air. A large car franchise in London had a workshop that had a compressor. The fitters in the workshop complained to the manager that the compressor was leaking and could he do something about it. The manager investigated the noise and found that the safety valve was lifting and to paraphrase the saying "A little knowledge is a dangerous thing" replaced the safety valve with a plug. A little while later the motor burnt out and instead of getting it rewound or replaced with the same size motor, he found a spare motor in the stores. Unfortunately, the replacement motor was of a size nearly double the size of the one that had failed. Now on compressors the motor is sized to the pump so that in the event of pressure switch failure the motor will stall before there is an accident. Now with the safety valve removed and replaced with a plug, the motor now being way larger than was required the "apprentice" who was supposed to turn everything off when leaving for home in the evening forgot to switch off the compressor. During the night the pressure switch failed ON. The next day when the manager and staff came into work they found that the works was missing two walls and the roof and that four customers cars were rite offs. At the public enquiry the comedy of errors that had led to the devastating explosion was laid at the feet of the manager who, due to his interfering with the plant, had caused the problem. The insurance company used this as an out and refused to pay out and the manager was fired. Had anyone been inside the building at the time they would have been killed.
Compressed air, which is a gas, is more dangerous that electricity, and as we all breath it and consider it as harmless it cannot hurt us. Oh yes it can. So gentlemen and ladies, please be careful and remember compressed gasses are dangerous.
Please keep making these models and I will put the story of my Stuart Turner Major beam engine, which I will finish one day,
Regards to all,
Graham Taylor. B.Eng. Verwood, U.K.