Delta PG-35 Specifications download pdf (Page 12)

12 LTL-XL Retroreflectometer DELTA

Important guide lines for the correct use of the LTL-XL

Positioning of the instrument on the road marking

Select an area of the pavement marking that is level when taking readings. The measurement

field is marked with a yellow sticker on one side of the base cover. The measurement field is

approximately 50 mm wide and 185 mm long. Ensure that the pavement marking to be meas-

ured before taking measurements is free of debris. Make sure that the instrument is stable po-

sitioned.

Reason: The LTL-XL has three support pads, each with a small footprint, two smaller in the

front and one larger at the back. An uneven marking or a small piece of gravel trapped below

one of the pads will move the measurement field and affect the reading.

Taking the measurement

Press the green OK button to take a single or double reading as selected. Do not put pressure

on the handle when taking a measurement.

Reason: Pressure on the handle can affect the measurement geometry and thus influence the

reading.

Number of measurements.

For accurate readings, do not take just one reading of a road marking. Three readings will

give a more accurate result than one reading. Five readings will give an even more accurate

result than three readings, etc. Take the readings in adjacent areas of the marking. Let the in-

strument calculate the average of the readings (fixed or moving average options).

Reason: A road marking’s retroreflectivity varies from area to area. It is not unusual to see

variations of 5% - 20% when the instrument is moved even less than 10 mm / ½” in either

direction.

Protection of the display/display shield.

For the protection of the display and longevity of the instruments keep the display shield

closed when the instrument is not used. For further information please see section 2.

Remember:

Read:

 LTL-XL is an optical precision instrument, handle with care.

 Keep the protection window and calibration unit clean and undamaged.

 Store in a clean, dust free and dry environment.

Measurement practise for road markings. This leaflet can be located on:

http://www.madebydelta.com/imported/images/DELTA_Web/documents/LO/roadsens

ors/ltl-x-xl/Measurement-practise-for-road-markings.pdf

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Delta PG-35 Specifications Page 12