Learn our top 5 tips for properly caring for your hot air welding tools and minimizing maintenance.
Together the VARIMAT V2, UNIROOF AT, and TRIAC DRIVE comprise Leister’s line of automatic welders for thermoplastic roofing materials such as TPO, PVC, etc. There are some key difference between these tools which make each suited to particular jobs on the roof.
Receiving an error message while on the roof can be extremely frustrating. Below you’ll find the common error codes you may encounter and an explanation of what they mean.
Taking the time to perform some quick maintenance tasks on your machine now can save you downtime during the roofing season. Whether you have a VARIMAT, BITUMAT, or TRIAC, the checks you should make are largely the same across all equipment.
The best way to minimize downtime to is to take proper care of your tools both on and off the roof. Here are our top 5 tips to keep your tools in good working order throughout the roofing season.
Inside every Leister hot air tool is a heating element composed of a ceramic honeycomb supported resistance wire filament (See below). Electric resistance wire heaters work on the principle that when electrical current passes through a conductor heat is generated, and the amount of heat generated is related to the resistance of the conductor.
Some resistance wire heaters are able to function without airflow because they have been designed in such a way that they will not reach temperatures above their safe operating limits. Examples include: a toaster, some ovens, wrap heaters, some space heaters, etc.
However, Leister heaters are designed to operate at very high temperatures—most are designed to heat airflows up to 650°C, and some up to 900°C—and as a result require airflow at all times. To reach these high air temperatures, the heating element must be capable of reaching even higher temperatures. Without adequate airflow, the element will heat up unchecked and will exceed safe limits, leading to the destruction of the element.
While Laser IR Thermometers are an extremely common tool, they are entirely ineffective for measuring the outlet temperature of an air heater. To understand why, we must first understand how this tool works. Laser IR Thermometers measure the surface temperature of an object by measuring the thermal energy emitted by the target. Knowing the amount of thermal energy discharged and the emissivity of an object’s surface, the object's temperature can be determined by the device.
When measuring a heater’s output air temperature, the largest issue with these tools is that they measure surface temperatures. As the heated air is transparent, the measurement will always be the surface temperature of a nozzle or a component of the heater housing; and frequently it will be an exterior surface. These items will always be cooler than the heated air, often by a significantly larger margin than the user would expect. To accurately measure the output temperature of an air heater you must measure air temperature and laser IR thermometers are incapable of doing so.
Growing insulation requirements have resulted in changes to roof structures in recent years. Rigid polyurethane (PUR), polyisocyanurate (PIR) or thicker mineral wool insulating materials with a higher level of compressive strength are now installed on the upper side of the roof deck. During the welding process, these insulating materials demonstrate virtually no elastic behavior resulting in a harder welding surface. This may cause air inclusions (bubbles) to form in the weld seam of mechanically fastened PVC roof sealing sheets under certain conditions, particularly if the roof substrate is uneven.
The new rake nozzle kit from Leister ensures that all leak-tightness and aesthetic requirements are met even in roof structures of this nature. The rake nozzle provides constant pressure on the lower PVC sheet. The soft silicone pressure roller ensures the pressure is distributed as effectively as possible over uneven and hard substrates.
If you're having problems with air inclusions in your welds, contact us today for more details.
A properly prepared substrate should be solid, evenly laid, and free from debris such as loose screws or stones.
If it is raining, welding must not be carried out without special protective equipment.
Welding must be suspended at temperatures below +5°C in order to prevent the material from being exposed to an excessively high thermal load (in accordance with DVS 2225-4).
In some cases, excessively high humidity can cause condensation to form on the welding surface, which has a negative effect on seam strength.
If there is strong wind, the tool may not reach the required welding temperature. This can be counteracted by raising the welding temperature by 20 to 30°C or reducing the speed by 20 to 40 cm/min. If the wind is excessively strong, the welding area should be shielded against wind or welding should be suspended.
Prolonged exposure to the sun can cause the material to heat up significantly causing thermal expansion. This causes wrinkles which makes the welding process more difficult and leads to an unacceptably high level of tension in the seam area when the material cools.
Maintaining the Tools
The air inlet and filter should be cleaned frequently and the heating element removed and cleaned periodically. This ensures the tool is able to produce the correct air volume and temperature output.
Using Generator Power
The generator must have the correct specifications in order to ensure safe operation:
Manual Welding Process
The distance between the pressure roller and the nozzle opening should be between 20 and 30 mm to ensure that the weld seam is joined as efficiently as possible. The pressure roller must be guided so that it is parallel to the nozzle. This will ensure that the welding process yields the best possible results (see images above).
The hot-air nozzle should be cleaned periodically to keep the contaminants out of the welding seam. A blocked nozzle will restrict the tool’s air output which may cause fluctuations in the output temperature.