ACQUIP News & Events August 25, 2023

The ERAG ELECTRONIC RADIAL ALIGNMENT GAUGE at a glance

Model CAT-1 (Contains both Large and Small Measuring Heads)

The ERAG CAT tool can directly measure the amount of diaphragm misalignment with the rotor in place. It negates the need for tight wire and/or laser alignment. This alignment method has been proven over thousands of hours of use.

System has a large (LCAT) and a small (SCAT) measuring heads. For newer turbine models there is also the µCAT (MicroCAT), which measures very small radial clearances (0.200” – 0.250”).

Key Features:

Directly measures the amount of diaphragm misalignment with the rotor in place.
Easy to use – direct readout.
Accommodates a wide range of turbine sizes.
High Accuracy – Resolution to .0001 inch (accuracy plus or minus.0005 inch maximum)

Measuring capability

For LCAT- annular spacing from .500 to 1.500 inch- packing width from 1.00 to 2.00 inch.
For SCAT- annular spacing from 375 to 1.000 inch – packing width from .500 to 1.500 inch.

How does it work?

Inserted into the empty packing groove, the Concentricity Alignment Tool (CAT) or ERAG Electronic Radial Alignment Gauge allows annular space variations to be displayed on an LCD display as it is pulled through the packing groove.
The head “rub bars” ride on the turbine shaft and the head lever arm rides on the ID of the diaphragm. As the head is pulled through the packing groove, the lever arm follows the contour of the diaphragm ID and the dimensional variation is displayed.
The ERAG have a main body to which there is pivotally coupled a U frame whose arms extend at an angle from its base, so that as the former is pivoted in one direction, the latter will correspondingly pivot in an opposite direction.
Contact points are provided to the arms and the bottom surface of the body, and the base of the U frame is biased by a spring-loaded slidable element within the body, which in turn is connected to a transducer.
An ideal way to accomplish alignment is with the rotor in place so the dimension from rotor to seal carrier can be measured directly. One of the best methods of measuring between the rotor and the carrier includes an ERAG.