Our sensors are easy to attach at the desired location due to their low weight reliably. It comes pre-mounted with a thin self-adhesive Very High Bond (VHB) tape (3M F9460PC) that will work excellently for most common applications. You only need to remove the peel-off tape to expose the glue before attaching the sensor to the surface.
This article provides guidelines on attaching the sensors under special conditions where the pre-mounted tape does not give the desired result.
As shown in the picture, the pre-mounted double-sided tape has a square opening in the middle to allow using other types of glue without removing the tape in the few instances desired.
For best results, always start with a clean and dry surface. If required, clean the surface as by 3M in this application note.
A removable attachment may be desired for trialing the placement of sensors. Apply a small piece of clay glue inside the center area at the backside of the sensor or on top of the peel-off of the tape. This allows for using the pre-mounted double-sided tape at a later stage when the sensor location is confirmed. We recommend the clay glue products below.
Alternatively, attach a double-sided repositionable tape to the existing peel-off tape on the sensor to save the original pre-mounted permanent tape for later use.
Mounting may require extra attention in some special cases.
- Rough surfaces
- Permanent mount
- Cold environment
- Wet environment
- Temperature sensors
1. Rough surfaces
Inherently, thin tapes work best on smooth surfaces since there is little material to absorb unevenness. Thicker flexible foam tape is recommended for such applications.
2. Permanent mount
The pre-mounted tape on the sensors is permanent VHB tape, and will in most instances provide a robust adhesive over time. If even better adhesion is required, use glue to mount the sensors. Remove the peel-off tape on the sensor before gluing to allow the glue to attach to the double-sided tape in addition to the center area of the sensor without tape.
The integrity of the surface limits the obtained strength in many cases. For example, the paint may come off the wall before the glue breaks. The following glues are tested on smooth surfaces with good results.
An alternative for rough surfaces is silicone-based glues. A glue giving some strength right after application makes assembly quicker. The following alternative is tested and found suitable.
3. Cold environment
Gluing to cold surfaces is challenging as most glues require temperatures around room temperature to cure. Some tapes are designed for use at low temperatures. The two types below can be used down to 0 °C, or below with less strength.
There is also a tape available from 3M suitable for use down to -20 deg C. This is meant for air sealing and is not double-sided, but it comes with a liner. However, the sensor nodes can be glued to the top side of this tape using the pre-mounted tape. This is a relatively thin tape working best on smooth surfaces.
“Superglues” can also be suitable on cold surfaces. For example, the following Loctite glue works well on wood and metal kept at -18 deg C.
4. Wet environment
Gluing to wet surfaces is challenging as most glues dissolve in water over time. But, there are tapes designed for use in wet environments, for instance, the two examples below from 3M. These tapes come in several widths, including 19mm, which perfectly fits the sensor. During installation in wet environments, make sure the surface is clean and dry. If you can not dry the surface before mounting, you can also use TEC7.
You can later remove the VHB tape using a sharp knife, fishing line, or a guitar string. Then, if the tape still is stuck to the surface, you can apply a citrus solution to the tape and let it work for a few minutes before rubbing off the glue.
5. Temperature sensors
The sensor will be thermally connected to the surface it is mounted on. The thin double-sided tape on the back of the sensor will attach the sensor close to the surface with a relatively low thermal resistance. Using the original tape will, therefore, result in a setup measuring mostly the surface temperature. In cases with a high surface thermal capacity (e.g., a concrete wall), the temperature response will be slow compared to the air temperature. In some cases measuring the surface temperature is desired.
If the air temperature is being measured, the sensor needs to be thermally insulated from the surface.
Insulation can be achieved using a thicker foam tape (e.g., Tesa 62612 or 3M VHB 4943F). However, in any case, a wall with high thermal capacity will impact the air temperature in the vicinity. A good solution is to install multiple sensors to overview the thermal dynamics of the total air volume and surfaces.
How to apply alternative tape
Most double side tapes come in a width of 19 mm or ¾ inch (19.05 mm). Follow the steps below to assemble the tape with the sensor.
- Cut a 19 mm length off the alternative tape
- Remove the peel-off-tape from the DT Wireless Sensor
- Attach the sensor onto the glue side of the double-sided tape
- Remove the peel-off-tape from the alternative tape when ready to attach the sensor
It is possible to buy pre-cut tapes from companies referred to as “converters for large-scale sensor mounting.” These companies specialize in providing customized tape solutions on base products from tape manufacturers. Tape companies like 3M and Tesa have partner converters in each region. A recommended supplier for Europe would be Alfast in Denmark.
Removing tape from sensor or wall
The best way to remove sensors from a surface is to lift them off with a thin sharp knife. Note that the surface and the sensor may be damaged depending on the strength of the surface. Use guidelines for trialing sensor location above if moving the sensor is desired.
Glue residues can best be removed by rubbing.