Abstract: Method and apparatus for controlling an instrument which can perform a specified cyclic process. The instrument's process is controlled by a computer which has two concurrently defined tasks: an operator task for running an instrument control program, and a compiler task for compiling new instrument control programs input by the instrument's user. The currently running program is suspended and a new program's execution is begun when (a) a new program has been successfully compiled by the compiler, and (b) the current program is about to perform a jump back at the end of an instruction loop. When a main instrument control program finishes executing, a new program is run if a new program has been successfully compiled; otherwise, execution of the most recently suspended program resumes. Thus a newly compiled program interrupts the currently running program only between instruction loops, and only as long as necessary to execute its instructions.

Abstract: A valve assembly for allowing entry of a sampling device or probe device from an ambient atmosphere to a vacuum chamber comprises an electromagnet means which controls a ball made of magnetic material. Upon entry of the device into an entry inlet of the apparatus, the ball is seated in response to activation of the electromagnet means so as to seal an aperture leading to the vacuum chamber. As the device is moved towards the vacuum chamber, the magnetic force is removed, which allows the ball to drop away from the aperture allowing entry of the device into the vacuum chamber. Upon withdrawal of the device from the vacuum chamber, the ball is actuated by the electromagnet to seal the aperture, thereby maintaining the integrity of the vacuum system.

Abstract: This relates to a filter unit which is particularly adapted for removing odors, bacteria and certain chemicals from water. The filter may be utilized as an in-line filter although it is preferable that the filter unit be mounted in parallel pairs with there being end plates at the opposite ends of the filter units to form a filter assembly. The end plates not only have required flow passages therethrough, but also function as supports.