Glossary Compressed Air and Efficiency

Compressed air is used for a wide range of uses:  Industry and the trades use compressed air for cleaning, for cooling and for pneumatic actuation.  Pneumatic tools such as drills, screwdrivers, jigsaws, and many other tools, are standard equipment.

Compressed air is used to drive cylinders and turbines as well as pneumatic post systems. Compressed air, as a popular source of energy, can be conveyed over large distances in pipelines. Compressed air is also used to transmit power in pneumatic brakes; brakes of this type are used in lorries and trucks, for example.

The first step in designing a compressorstation and the respective compressed air network is to determine the requirement for compressed air. This enables the free air delivery required by the compressor to be identified. The first value to be found when determining the capacity of a compressor station is the expected total consumption. The consumption of the individual consumer devices is added together and adjusted to the operating conditions with the aid of various factors. The compressor can then be selected according to the resulting free air delivery.

Pneumatic tools, for example, which are among the most frequent consumers of compressed air in industry and the trades, generally require compressed air with a working pressure of 6 bar. There are also versions that use other working pressures, depending on the application and the power requirement.

Compressors are generators of compressed air. These machines are used for pumping and compressing gases to any pressure. Fans are also compressed air generators that pump atmospheric air as flow machines. With fans - additional compressed air generators - only slight changes to density and temperature occur. Other machines that draw in gases and steam in order to create a vacuum include vacuum pumps.

A central compressed air supply needs a network of pipelines to deliver compressed air to the individual devices. The network must meet various conditions in order to guarantee reliable and cost-effective operation of the devices.
 

• adequate free air delivery: Each device in the network must be supplied with the required volume flow at all times.
• the necessary working pressure: Each device in the network must have the necessary air working pressure at all times.
• compressed air quality: Each device in the network must be supplied with compressed air of the required free air delivery and quality in the pipelines at all times.
• low pressure loss: The pressure loss in the network must be as low as possible for economic reasons.
• operational reliability: The supply of compressed air should be guaranteed as far as possible. If pipes are damaged, repair and maintenance work must not put the entire network out of use.
• safety regulations: The relevant safety regulations must be complied with at all times in order to prevent accidents.

Compressed air systems generate pneumatic energy reliably and according to demand. Depending on the intended use, compressed air systems can either be mobile or stationary. As an environmentally aware company, BOGE supplies compressed air systems with proven energy efficiency. The design of our compressed air systems is constantly undergoing improvement by our developers and designers to make our systems more cost-effective and eco-friendly.

Compressed air is a source of energy in just the same way as electricity.  Regular system inspections and maintenance are of decisive importance for effectively keeping compressed air costs to an economically viable level. High costs for compressed air generally point to outdated compressors which should be replaced as quickly as possible. For only low compressed air costs are cost-effective and eco-friendly.

Compressed air costs are comprised of three factors:

• Servicing and maintenance costs: This part of compressed air costs includes the wages of the fitter, spare parts and consumed materials such as lubricants and cooling oil, air filters, oil filters, etc.
• Energy costs for electricity and fuel for heating the compressor
• Debt service comprises the compressed air costs concerned with interest and the repayment of capital tied up in investments such as compressors, treatment and pipeline network. These are the depreciation and interest charges.

There are many factors that decide the overall efficiency of a compressed air station. Efficient components are an important step toward positive overall efficiency. However, top efficiency, with an average savings potential of around 33 %, can only be achieved by scrutinising the entire system.  Leak minimisation, pressure reduction and the use of intelligent control devices are just some of the criteria to consider where energy efficiency is concerned.

Compressors with demand-based frequency control increase efficiency and help to save costs. Where compressed air demand fluctuates sharply, the most energy-efficient and cost-effective operating mode is obtained by adjusting the free air delivery of the compressor through infinitely variable frequency regulation of the motor speed. Frequency-controlled screw compressors can significantly reduce energy costs. Frequency controls can be integrated into every existing compressed air station.

Increasing environmental awareness and rising energy costs have led many compressor system users to the view that the enormous potential of compressor heat must no longer be allowed to escape unused. High performance heat recovery systems are very much in demand. Heat given off by compressors is utilised and extracted by the cooling medium (air/water). This coolant contains up to 94 % of the electrical energy intake of the compressor in the form of heat. It is used to heat rooms, and to heat process water and heating water.

The efficiency classes for electric motors are referred to as IE1, IE2, IE3 and IE4.

• IE4 - Super premium
• IE3 - Premium efficiency
• IE2 - High efficiency
• IE1 - Standard efficiency

 

In most cases, it pays to use a motor belonging to the highest efficiency class that is currently available (formerly EFF 1, now IE3), even if this is not, or not yet, a statutory requirement. The additional outlay for an electric motor from a higher efficiency class is usually recouped over a short period of time.
From July 2021 onwards, the mandatory minimum efficiency required for motors with power ratings between 0.75 kW and 1000 kW will be IE3.

A leakage refers to a leak in the compressed air system. Leaks can often reach inconceivable volumes and are thus a significant energy waster and cost factor. It is estimated that on average 30 percent of the generated compressed air is lost through leaks.

A monitor provides the compressed air user with clear data about whether or not leak detection and repair are required in the compressed air network. The leakage monitor independently measures loss and displays it on the screen of the compressor control system.

The human ear cannot detect leaks. Ultrasound measuring equipment can be used to detect leaks in compressed air systems.
Measurements with AIReport are most effective, because they also highlight inefficient idle times in screw compressors. These types of measurement provide information about the ideal compressor combination with the most cost-efficient operation .

Oil-free compressed air generation works on a principle which dispenses with the cooling and lubricating function of the oil. The special airend and the BOGE cooling concept have been designed to produce oil-free compressed air with the utmost safety and maximum efficiency. This is indispensable for sensitive fields of application such as the food and health industry.