Teledyne Technologies Inc. will acquire the gas and flame-detection business of 3M Co. for $230 million in cash. The Thousand Oaks aerospace, marine and digital imaging products manufacturer expects to close on the deal in the second half of the year. About 500 employees from 3M will join Teledyne after the transaction is complete. Teledyne Executive Chairman Robert Mehrabian said that the 3M gas and flame detection business uses similar technology and serves related markets to Teledyne’s environmental instrumentation business but that the two companies do not compete against each other. “This business will become a long-term core business of Teledyne, and we look forward to welcoming it and its employees to Teledyne,” Mehrabian said in a statement. The 3M business unit, based in The Woodlands, Texas, includes the brands Oldham, Simtronics, Gas Measurement Instruments, Detcon and select Scott Safety products. Shares in Teledyne (TDY) closed up $6.48, or nearly 3 percent, to $250.63 on the New York Stock Exchange on Wednesday, a day when the overall markets were up less than 1 percent.