Nomis SuperGraph – Quick Guide

(When using the instrument to measure ground borne vibration arising from civil engineering activities, piling etc)

Overview

The SuperGraph is a very advanced ground vibration monitor enabling ground-borne vibration to be monitored with ease. Just two button presses after switch on are required to begin a monitoring session.

The integral high speed printer is supplemented by a data-logging memory. The instrument has sufficient memory to store over a weeks worth of continuously monitored data, when used in Bar Graph Mode.

The instrument has the ability to store user and location information so that several users may use the instrument with their parameters (location data, distance to vibration source, etc). This saves operator time and the inconvenience of having to repeatedly alter the set-up for different users and/or locations.

A single auto-scaling range of 0.1mm/s to 130mm/s means no more over-range errors.

Set Up

Connect* and position the tri-axial geophone sensor unit** before switching the instrument on. The instrument will show its main menu with four items. The first item, self-trigger will be highlighted, use the up and down arrow buttons on the key pad to navigate. Select Bar Graph Mode and the first item, Monitor will be displayed. If the user set-up is correct, i.e. the user wishes to use the existing settings, Press Enter to begin monitoring.

To change the set-up, select Item 2 Edit Mode and press the Enter button. See Edit Mode below.

On completion of the monitoring session, press Escape and press Enter. Then hold down the Off button for 2 seconds.

Clean and dry all accessories before storing them in their compartments.

Whilst Monitoring in Bar Graph Mode – Note that after 2 minutes the display will go blank to save energy. Pressing a yellow button brings back the display.

The LCD display, by default, shows Monitoring… with the date and time and the tri-axial data and the highest recorded PPV’s in mm/s and frequencies in Hz for the Summary Interval selected during the set-up (say 1 Hour). Pressing the up arrow button shows the Impulse Results every second as they are being recorded, a very useful feature when it is essential to prevent levels from exceeding pre-defined limits. Pressing the down arrow button takes the display back to the Summary Interval and pressing the down arrow button a second time shows Job Peak Results, the highest levels recorded since the monitoring session began.

Notes:

1. Always keep the lid closed when in use to maintain weatherproof integrity.
2. Charge the battery for twenty-four hours every two weeks, whether the instrument is used or not.
3. On the right hand side of the printer is a red lever that must be in its forward horizontal position, otherwise the printer will not print.
4. Note the paper path for future paper loading.
5. Using Edit mode is self explanatory and enables user, location, distance to source, maximum charge weight, trigger level and event time information so that several users may use the instrument with their parameters. Navigation is by way of the UP and Down arrow buttons, Plus and Minus buttons (for Date & Time) and the Enter button.

*If the sensor is connected after switching on, all readings will be invalid.

Edit Mode

In edit mode characters are entered using the keyboard and the up & down arrows. The cursor is moved forwards & backwards using the + & - keys. At the Main Menu, select item 2, Bar Graph, by pressing the Enter button. Then select item 2 Edit, by pressing the Enter button.

A useful default for Bar Graph mode is:

Sample rate: 1024
Company: The Company name may be entered
Seismograph Location; The location name may be entered
Notes: A place to record any other information that may be useful
Distance to Source: The distance between vibration source and monitor may be entered
Operator: The operators name may be entered
Sensitivity: High
Monitor Bar Graph: Seismic
Bar Scale: 12% (16 mm/s)
Bar Interval: 60 Seconds
Summary Interval: 1 Hour
LCD Impulse Time: 1 Second
Bar Printout Result: Peak
Report Displacement: No
Save Setup: Yes
Name: A unique name for this setup

After input of the required parameters, the option to save is shown. A name for the set-up will allow these parameters to be used again, when the named set-up is chosen.

To use the pre-set settings, after switch-on in the main menu of four items, select option 4 by using the down arrow button to Saved Settings and press Enter, then highlight the desired set-up by using the arrow buttons and press Enter.

Using the Help Menu

After switch-on press Help
Only the first option is currently enabled, press Enter.
To navigate through the options use the arrow buttons and the Plus and Minus buttons to change the time and date. Press the Enter button to select an option, and Escape to return to the menu. The choices here are self explanatory.

Events in memory may be previewed on the LCD via the Help menu: Summaries Events.

A sleep function (Timer Mode) is available through the Help menu allowing the instrument to begin monitoring at a pre-determined time; each day, once a week or once a month. A useful option, when the instrument is used for long-term unattended monitoring, to prevent excessive amounts of data caused by spurious triggering.

**Placing the tri-axial geophone sensor unit

One of the most critical aspects of vibration monitoring is the placement and coupling of the measurement transducer. The accuracy of reading is only as good as the quality of the connection between the transducer and the ground surface. This connection, known as coupling, is vitally important in obtaining valid results. When Peak Particle Velocities are greater than 10mm/s the transducer should be buried completely, when the measurement surface consists of soil. A sandbag can also be effective if used properly, being loosely packed and large enough so that, when placed on the sensor, all sides of the bag are resting firmly on the ground surface. When measuring on a firm surface, attachment can also be by means of epoxy resin or bolting. The SuperGraph is supplied with three ground-spikes to enable easy coupling of the sensor when ground conditions allow their use. The sensor must be used only in a horizontal orientation with the arrow pointed towards the vibration source.