NOVACOM offers a wide range of venturis suitable for each application and meeting the requirements of different sectors of activity.
NOVACOM vacuum generators, also known as ejectors or pneumatic vacuum pumps, operate on the principle of the venturi. Mono-stage, multi-stage, anti-clogging, and pneumatic transport venturis are distinguished.
The choice of a venturi is made according to the application and the required flow rate (or air suction capacity). For the suction of tight parts, a high level of vacuum (55 to 80%) will be recommended, while for the suction of porous parts, it will be necessary to favor a high flow rate of air suction, i.e., a lower vacuum (30 to 55%).
The flow rate is expressed in normal liters per minute (Nl/min), liters per second (l/s), or cubic meters per hour (m3/h).
- Example with a single-stage series VT Venturi
Here, is the single-stage venturi VT 10 mounted directly on the suction cup?
- Example with a TP series pneumatic transport system
Here, the TP 102 pneumatic transport system sucks up and removes rubber waste resulting from tire manufacturing.
- Example with a VCR 250-2 pneumatic gun series
Here, the anti-clogging Venturi VCR 250-2 is handling porous and dusty tiles.
OPERATING PRINCIPLE
To achieve a vacuum in a vacuum system, a very large portion of the air inside must be evacuated. Venturis operate through a compressed air supply. The jet of air emitted through the venturi nozzle entrains ambient air and is then discharged into the mixer and escapes through the silencer. The ambient air intake creates the vacuum at the vacuum orifice.
The diameter of the venturi nozzle defines its power and therefore its suction capacity. As for the mixer, its profile defines the maximum vacuum level achieved by the venturi. The flow rate and vacuum level must be adapted for each application. Venturis allow for the generation of a relative vacuum in a system. As for vacuum manipulation, the internal volume of the suction cups to be emptied and the volume of the vacuum system (pipes) allow for the determination of the capacity of the venturi.
GENERAL SELECTION CRITERIA
In order to choose the appropriate venturi for the relevant application, it is necessary to know the total air volume of the system, the desired vacuum level, and the time available to reach it.
The type of suction cups installed on the vacuum circuit as well as the product(s) being handled participate in determining the necessary suction capacity to evacuate the air.
The choice of a venturi depends on several factors such as:
• lhe weight and size of the parts
• compliance with cycle times:
The operating rate of a machine includes pick-up time, transfer time, and release time.
The type of parts to be handled (porous, sealed):
If the part to be handled is porous or irregular, air leaks will be inevitable. In order to compensate for these leaks and thus maintain the grip, it is necessary to have a high flow rate. The vacuum level must therefore be low, between 30% and 55% vacuum. If the part to be handled is sealed and without leaks, the vacuum level must be high and can range from 55% to 80% vacuum, or more in the case of a very high vacuum requirement. The choice of the venturi is therefore made according to the emptying time of the vacuum system.
For example:
For picking up cardboard, a porous material with air leaks, use a venturi at 40% vacuum with a high flow rate such as the single-stage VT series venturi (low compressed air supply pressure, 3 bar, to reach 40% vacuum). For picking up glass, a sealed material without leaks, use a venturi at 93% vacuum with a low flow rate such as the multi-stage VMEH series venturi.
To handle parts safely, it is important to choose the appropriate venturi.
*Coefficient of 2 for horizontal picks and 4 for vertical picks.
DIFFERENT TYPES OF VENTURIS
According to the number of nozzles, we distinguish between single-stage venturis and multi-stage venturis. In the case of multi-stage venturis, the nozzles are usually arranged one behind the other. Multi-stage venturis achieve a much higher suction capacity for much lower compressed air consumption.