We would like to complete our short "Vacuum in Woodworking" series with today's article. This time, we will focus on centralizing the vacuum supply for an entire plant. A central vacuum supply can always be wise if several machines are clamping with vacuum
. In this process, the individual vacuum pumps directly connected to the machining equipment are removed. A network of pipes is then used to connect the equipment to a vacuum system that can be located outside the production area in a separate room.
Whether a central vacuum system (Fig. 1) is reasonable for a woodworking plant depends on different factors:
- The number of vacuum pumps used
- Operating times of machining equipment and vacuum pumps
- Spatial situation
The benefits of a centralized vacuum supply when compared to decentralized vacuum generation with vacuum pumps located in the direct vicinity of the machining equipment are:
- Highest degree of energy efficiency
- Highest level of reliability
- No machine downtime during maintenance
- Effective use of waste heat
Some practical considerations
When acquiring machining equipment, usually one or – in the case of two machining tables – two vacuum pumps are delivered, for example. The performance of these vacuum pumps is designed for the maximum requirements and usually has additional reserve capacity. Depending on the material used, work pieces and processing times, this type of vacuum pump can be oversized. For example, if a plant has several machines with a total of 15 vacuum pumps working in three-shift operation 24 hours a day, the energy consumption for the plant's vacuum supply alone is not insignificant. Here is an example:
15 vacuum pumps, each with 5.5 kW, consume 1,980 kilowatt hours (kWh) in 24-hour operation. At an electricity price of 0.10 EUR/kWh, the resulting daily energy costs are close to EUR 200. At 220 working days per year, the annual electricity costs amount to EUR 43,560. The actual clamping times during which vacuum is really needed only makes up a fraction of the operating time. In turn, this means that, in practice, vacuum pumps are often in operation but not being used. For vacuum pumps requiring intense maintenance – for example, dry-running rotary vane vacuum pumps – this shortens the maintenance interval for exchanging the vanes, which in turn increases the operating costs. These costs are avoidable with a vacuum pump that is not always being used.
Central vacuum supply
In many cases the number of vacuum pumps in a central vacuum system can be cut in half as compared to decentralized vacuum generation.
If a central vacuum supply is used, no individual vacuum pumps are needed at the machining centres. The machining centres are connected to a central vacuum system using a network of pipes. When designing this type of vacuum system, it becomes apparent that it is possible to manage with significantly fewer vacuum pumps. In many cases the number of vacuum pumps can be cut in half as compared to decentralized vacuum generation.
A central vacuum supply can work much more energy-efficiently
than the individual vacuum pumps directly at the machining equipment can, simply due to less vacuum pumps.
The performance of the vacuum system adjusts to meet the actual demand.
The control system for this type of vacuum system automatically activates only the number of vacuum pumps required to maintain the pumping speed or vacuum level that is currently needed. This means the performance of the vacuum system adjusts to meet the actual demand. In addition, the vacuum pumps are operated alternately, so they are all operated for approximately the same amount of time. The network of pipes from the vacuum system to the machining equipment can serve as a vacuum buffer, which means that it is constantly evacuated. The advantage here is that the vacuum required for clamping is available immediately when the valve on the clamping equipment opens. Practical experience shows that even when there is generally a smaller number of vacuum pumps in this type of centralized vacuum system, not all are constantly in operation, which facilitates additional energy savings. As a rule, MINK claw vacuum pumps
are built into these vacuum systems. They can be equipped with frequency-controlled
motors that allow even more finely coordinated adjustments to the performance, which once again leads to energy savings.
A central vacuum supply ensures the highest degree of reliability. If a vacuum pump should fail, this does not affect the machining process at all as the remaining vacuum pumps deliver more output accordingly. Larger leaks can also be bridged in this way.
MINK claw vacuum pumps work nearly maintenance-free. Changing the gear oil can be done during operating time. The technician does not need to access the production rooms to do it. He can shut one vacuum pump off directly at the vacuum system and change the gear oil without compromising the performance of the vacuum system.
Making use of waste heat
Concentrating all vacuum generators in one room makes it easy to make use of the waste heat from the vacuum pumps. This can be done by simply feeding the exhaust air into a heating or warm water system or also by converting the heat energy with a heat exchanger. In this case, finding the most effective solution also depends on the individual conditions on site.
Centralization of the vacuum supply requires several basic considerations. The savings in energy costs or general operating costs, which can be drastic in some cases, should be weighed along with the investment costs. The costs for the actual central vacuum system can be reduced by integrating any already existing Mink claw vacuum pumps. The site and construction conditions are pivotal cost factors with regard to the pipeline network. Also important here is that a technically optimal and economically efficient solution can only be realized with the help of a designated vacuum expert. Busch Vacuum Pumps and Systems has decades of experience in installing central vacuum systems worldwide and can provide many references in this field.