To install the AMH masses, a binary mass loading tray isplaced on the piston cap and a mass bell is installed over the tray. The mass set’s main mass discs are hung from the mass bell. Tubular binary masses are placed in descending sequence on the mass bell hanger and on the tray.
The mass handling system is placed over the installed mass set and controlled by the PG7000 platform, using RS232 communications from the platform’s COM3 port.
To load a specific mass value, the mass handling system raises the entire mass load above the piston upper end of stroke to the mass selection position. The mass is raised by a pneumatically actuated lifter acting on a lifter shaft connected to the binary mass spindle. Each tubular binary mass that is not to be loaded is held in place by engaging three selector pins. The three main mass columns are rotated synchronously so that the main masses not to be loaded are held in place by the columns’ retention ledges and masses to be loaded face release flats. When the mass selection is complete, the lifter moves down, placing the lifter shaft, binary spindle, bell and all the released masses onto the piston.
The AMH mass handling system is designed and tested to provide years of reliable, maintenance free mass manipulation.
Mass loading control
Control of the mass handling system is integrated into PG7000’s intelligent operation. In pressure entry mode, when a target pressure command is entered from the front panel or remotely, PG7000 calculates the mass required to achieve the target pressure. It then stops piston rotation and loads the mass value by sending a command to the AMH. The true value of mass loaded and exact pressure value achieved are reported and updated real time. In mass entry mode, the requested value is loaded directly.
The mass actually loaded by the AMH is as close as possible to the target value within AMH’s 100 g loading resolution. If more precise mass loading is specified, the operator is instructed to load trim masses on the trim mass tray (not available in absolute mode with vacuum reference).
Access to piston-cylinder module
The same piston-cylinder modules used in PG7000 with manual mass handling are used with AMH. The piston-cylinder module can be removed and reinstalled in less than 5 minutes, and requires about the same amount of effort as a single, manual mass handling calibration sequence.
The piston-cylinder module is accessed by removing the AMH mass handling system and masses. The procedure is to load all of the mass on the piston so that no masses are in contact with the mass handler. The mass handler is lifted off of the PG7000 platform vertically, leaving behind the complete loaded mass set. The masses are then removed manually to access the piston-cylinder module.
AMH-38, 38 kg under vacuum for PG7601
The AMH-38 provides automated mass handling of a 38 kg mass set for the PG7601 piston gauge platform. The mass handling system is integrated into a vacuum chamber which provides KF40 vacuum fittings for connection of a turbo molecular vacuum pump and external vacuum gauge if desired. Automated mass handling eliminates the need to break the vacuum between pressure points and reference vacuum as low as 0.01 Pa (< 0.1 mTorr) can be maintained indefinitely.
AMH-100, 100 kg for PG7102, 7202, 7302
The AMH-100 provides automated mass handling of a 100 kg mass set for the PG7102, PG7202 and PG7302 piston gauge platforms.
The 100 kg mass set results in a very wide range on a single piston-cylinder module, minimizing the need for piston-cylinder changes. A mass set of less than 100 kg can be configured if less than 100 kg is needed.