Measuring tapes are used to measure the linear distance between two points. Measuring tapes used by surveyors in the field come in all different shapes and sizes and have different applications.
The 4 different types of tapes used in surveying for point-to-point measurements are:
- Metal tapes,
- Fibreglass tapes,
- Cloth tapes, and
- Invar tapes.
Metal Tapes
The most common type of tape measure a surveyor uses in the field is an 8-meter metal tape measure. They are popular as they are lightweight and compact, easy to carry around, durable, and they are able to measure accurately to the millimeter with good measuring practices the distance between two points.
Metal tapes can come in various lengths ranging from 1 meter to 100 meters. The measuring tape width can also vary between 6 to 16 millimeters.
The measurement units on a tape can depend on what country you are buying one in. They can come with both metric and imperial measurements printed on either side of the tape, or they can have only metric or imperial units on the tape.
Metal tape measure blades can be made out of different materials including steel and stainless steel.
Metal measuring tapes can be either flexible or non-flexible. If you try and measure a curved surface with a non-flexible tape measure you will likely permanently damage the tape. Also if exposed to moisture or retracted with dirt on the tape, this can cause the tape to corrode and affect the recall of the tape.
Metal tapes are used in construction, manufacturing, woodworking, and mining industries, and many more are not listed.
Fibreglass Tapes
Fibreglass tapes are commonly used when accurate distances are not required to be measured. Applications for their use can be:
- Measuring out round drill hole/blast pattern between two surveyed points.
- Measuring rough offset from existing features on a site over long distances.
- For measurements in areas near live electric services.
Advantages of fiberglass tape measures include:
- Not conductive of electricity.
- Not corrosive.
- Flexible and able to be retracted.
- Cost-effective.
Disadvantages of fiberglass tape measures include:
- Not as accurate as steel measuring tapes.
- Is able to stretch with tension put on the line.
- Not stiff and can be difficult to use in high winds without an assistant to help you.
Fibreglass tapes can come in a variety of sizes, from as short as 5 meters, all the way up to 100 meters.
Cloth & Linen Tapes
Just like fiberglass measuring tapes, cloth and linen tapes are not suitable where an accurate measurement needs to be taken. The cloth or linen tape stretch when tension is put on the line and shrinks when exposed to water.
These are not common measuring tapes and personally, I have never seen another surveyor use one of these in the field. The only time I have actually seen one of these is in my Dad’s toolbox, which was given to him by his father.
Invar Tapes
If you need to take very accurate measurements with a tape measure, then the invar tape is the most accurate of all measuring tapes.
Invar is an alloy, made up of 36% nickel and 64% steel. This alloy has a very low coefficient of thermal expansion, which makes it an ideal alloy for a tape measure required to measure precise distances as the tape is not as affected by changes in temperature as a steel tape measurer.
Invar tapes can be very expensive which is why they are only used selectively in the field for tasks that require high precision.