I repair machines in a printing factory. If you have a good pump, I can help you sell it. The plate-making machine uses a vacuum, but many plate-making machines are now replaced by CTP, which uses an air compressor. Printing machines and folding machines use air pumps, which are divided into oil-free and oil-filled ones. The former is more common, and air compressors are also used a lot. I haven't heard of anything else