Bentley displacement setting
Thread Content
:) Is the Bentley displacement, which is calculated based on the serial value, the new 0-point value? Is the value calculated by pushing it to the working surface the value closest to the center point? Is the center point value the new zero value?
No, first push it to the working surface and measure a value with a micrometer; then push it to the other side, the non-working side, and measure another value – by doing this, the displacement can be calculated. After that, use the micrometer to move it to the middle position and install the probe there
API670 mentions something regarding the zero point for displacement; it seems that the midpoint of the shaft’s displacement should be used as this zero point. I think a practical and reliable approach is to push the shaft firmly against one of the thrust bearings, and then perform calculations using the value obtained by dividing the gap voltage by two along with the zero-point voltage. The sign of this value depends on which side of the shaft is being used, as well as the settings on the BENTLY equipment. The probe’s position should be adjusted according to these calculated values, so that the displacement is zero when the shaft is at the midpoint.
Push to the side, the calculated value. For example, if the value of 10-0.18/2*7.87 is made negative, it represents the intermediate value during normal rotation; that’s right
That’s what it means, but the direction must be determined accurately – that is, the sign of the 10 in the formula and the sign of the voltage value after calculating the gap voltage. It also depends on whether the probe is installed on the housing on the side of the main thrust mechanism or on the side of the auxiliary thrust mechanism, as well as on which side you move the bearing in order to adjust the probe.
A layperson here, thank you. There are many talented people here. And there’s also that one with a magnetic holder and a dial indicator – how is play measured? Are there any instructions for using it in this regard?
I haven’t used it myself, but I’ve seen the maintenance team use it. The magnetic bracket is attached to a bracket that remains stationary relative to the shaft, and then the measuring probe of the instrument is placed against the surface of the shaft to zero it out. The shaft is moved back and forth by the maintenance staff in order to measure the amount of movement
It’s zeroing out, the rotating axis. Check the dial gauge reading
First, the mechanical team checks for play, then moves the shaft to one side, launches the 3500 software, establishes a connection, selects the corresponding module (channel) from the main screen, and chooses Verification from the Utilities main menu. Once in this screen, the real-time data from the probe is displayed. If the probe has already been installed and the compressor shaft is on the side away from the probe, with a play of 30 steps (0.3 mm), adjust the voltage value until the real-time displacement value shows 0.15 mm. At this point, the zero point for the probe in that channel has been set; save the settings and proceed with installation.
When using this method, note that the zero-voltage must be within the range allowed by the software. It is probably around 9–11V; if the two displacement probes on the same side have the same sensitivity, their installation voltages do not need to be identical, which facilitates on-site installation.