HOW TO SET SLOPES (FALLS/GRADES)
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Working Example (when you know the % grade to set)
The following description in this guide, explains the general principles of setting a Slope (Fall/
Grade), using the FRE-203XT, when you know the % grade to set.
Equipment
You will need the FRE-203XT laser level, the radio remote control, a surveying tripod, measuring
staff (rod) with mm scale and a laser detector/receiver. It is not essential but having the remote
control for the laser level is preferable.
Site Conditions
There are many diff erent work site scenarios. As an example, we are assuming that you are
outside, on a site with a clear fi eld of view and planning to set drainage falls.
All above ground and below ground drainage pipes should be laid to an adequate gradient. The
fall in a pipe is defi ned as the vertical height by which the pipe drops over a known distance, as
an example a 2.5% gradient is a fall of 1m over 40m or 1:40. (1 in 40).
Typically, surface water or foul water drainage pipes are set between 1:40 to 1:80.
If a gradient is too steep i.e. steeper than 1 in 40, the liquid may run faster than the solids in a
foul water pipe thus leaving the solids stranded, which could then block the pipe. Conversely,
if a gradient is not steep enough (usually less than 1 in 110), then the pipe may still block, if the
solids slow down and become stranded.
Procedure
Place the FRE-203XT horizontally on the surveying tripod, switch it ON and allow it to auto (self)
level. The tripod height is unimportant.
Position your extended measuring staff on the ground next to the laser & clamp the detector to
pick-up the red rotating beam with a continuous tone on the detector.
Setting a 1:40 gradient:
Note the axis direction of the gradient to be set, via the laser’s top cover markings.
In this example, the Y axis in line with the laser’s keypad is to face down the slope.
Press the red grade button, X axis fl ashes. Press X/Y Axis Selector button ONCE only so that the Y
axis fl ashes. Using the + button input the 2.5% grade value. To fi ne adjust, use the + or - buttons.
Important:
The Y grade value must show a PLUS value, to ensure the slope is set down from the
front face of the laser.
Press X/Y button again. The laser will stop rotating, adjust to the 2.5% grade then restart. If the
laser is switched off , this value is lost.
Keep the detector clamped in place on the measuring staff & by moving away from the laser,
keeping a continuous tone on the detector, the ground can be cut away at the base of the staff ,
following the 2.5% grade (1:40 slope) set by the laser.
User Tip
Use the remote control for convenience and it also prevents disturbance to the laser.
Use the included “Gradient Conversion Chart” on page
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to set other slopes.
