Blog: air motors
Short and sweet update.
Deprag have updated their POWER LINE of air motors. Especially the motors in the 1.6 to 6.0kW range. The big news is that there are now 12 ATEX approved motors with planetary gearboxes and IEC flanges. 4 of those ATEX approved motors have a working speed at or close to 1500rpm, so these motors will be able to directly replace an electric motor provided the flanges match up.
The best news is that the new motors are cheaper than the old range and in many cases more powerful!
Unfortunately compressed air turbine powered grinders are overlooked by factories because of their high initial cost compared with cheaper tools. Here we are going to go through and explain some of the advantages of these grinders andd try to explain how they will actually save your organisation money in the long term.
ELECTRIC VS AIR POWER:
240V electric powered grinders are readily available and reasonably cheap, but iunder the stress of continual use an industrial quality air grinder will always outlast the electric grinder as long as it has a quality air supply. Air grinders will not be affected by dust in the air, they cannot be overloaded or overheated. The air grinder will also be lighter than an electric grinder with the same power output. Especially in the case of 230mm grinder, air grinders are available with higher power outputs. Please note! Most electric tool manufacturers quote the max power input to their tools. Air tool manufacturers quote the max power output! So a typical 1000W 240V grinder will only output 600 to 700W of power. A 1000W air grinder outputs 1000W as long as you have enough air to run it.
POWER to WEIGHT RATIO:
Often we want maximum power without the weight right? It's not helpful to have high power and high weight or low weight with low power. Higher power with lower weight means that the work is done faster and with less fatigue. Less fatigue means less chance of accidents, less breaks and less down time.
Air powered grinders are often chosen over electric tools because for a given power, the vane motor powered grinder is going to be lighter and smaller than a 240V electric grinder. Smaller and lighter tools mean that the operator is not going to be as tired, he can work longer without breaks and there is less chance of injury.
Turbine powered grinders take this a step further. For example:
Why is high power more important? Because it saves you money of course!
- Faster material removal - time is money right? If your trigger time is 3 hours per day, your extra material removal can be a tonne or more over a year compared to a vane powered tool.
- Optimal cutting / grinding speed means that your abrasives last longer - save over 30% on your abrasive costs if you are using quality abrasives!
- If low powered tools are used, the speed drops when pressure is applied resulting in faster abrasive wear. HIgh powered tools with speed governors do not slow down.
LOW MAINTENANCE COSTS
Turbine motors have all the advantages of vane motors - (cannot overload, cannot overheat, not affected by dust etc), but they do not have vanes, which is a wear part. As long as they have clean, water free compressed air, you can depend on them for a trouble free lifetime whereas vane motors have wear parts - especially vanes, that have to be replaced every so often.
Compressed air is EXPENSIVE. The turbine compressed air motor is already a comparatively efficient air motor (see the above comparisons) which of course means it will cost you less to run your compressor. Deprag has also taken advantage of some of the turbine motor's characteristics to make them even more efficient.
Deprag has included a speed governor in it's range of turbine grinders which means that when the tool is not under load it consumes less than half of the air that it uses when under full load. As the load increases the govenor progressively opens the air inlet valve, increasing the air supply and thereby increasing the power. The governor also maintains the correct speed no matter what the load - extending the life of your abrasives.
To really understand the value of turbine powered angle grinders you need to look past the initial cost, especially if grinding is a big part of your business. The lifetime cost of every tool has to be considered. Compressed air, abrasives and man-hours are not cheap and they all add up over time. Many companies have done the tests and have come to realise that the savings we are talking about are real and significant. Don't ignore the facts!
Take a look at the Deprag 230mm Turbine grinder in action here: https://youtu.be/sufhzTdhMso
Air tools and air motors are still assumed to be safe for use in explosive environments and in underground mines, but are they really? How safe is “safe”?
The simple answer is yes, in general air tools are safe for use in hazardous areas, but not always. Many types of cutting & grinding tools are not safe no matter what type of motor they use – for example grinders. Other tools like drills, hacksaws, impact wrenches and air motors are widely considered to be safe. The issue is how safe are they really?
Depending on the cutting speed, some drills and air hacksaws are not safe for use in hazardous areas at all. Also the quality of the motor and it’s components can lead to overheating of the bearings.
Some gases and dusts can explode at very low temperatures, for example carbon disulfide can ignite at 90 degC.
So what temperature does the air tool or air motor run at?
Do all air powered motors run at the same temperature?
Of course of course they don’t.
ATEX approvals were introduced in the EU to certify the safety of equipment that is going to be used in hazardous areas. All tools and equipment that have ATEX approvals are marked with a code that identifies:
- Which zone the equipment is safe to be used
- What temperature range the tool operates
- If the tool is suitable for operations where explosive gas and/or dust is present
- Whether the tools is safe for underground or general industrial use
ATEX approvals clarify whether or not an air tool or air motor is safe to use in a particular hazardous area thereby avoiding assumptions about safety that can lead to serious injuries or catastrophic explosions.
Our Undergound mining impact wrenches are also ATEX approved for use in underground coal mines.
Deprag’s Green Energy Turbine generator can be used in either a direct or an indirect configuration.
In a direct configuration a high pressure gas is run through the turbine. Electricity, lower pressure and lower temperature gas is the result.
Some examples include:
- Energy recovery in metal smelters
- often molten metal is cooled by compressed air. The compressed air flows through cooling tubes and is normally exhausted to the atmosphere. The hot, compressed air can be run through the GET and the recovered electricity can be either used by the smelter or fed back to the grid
- Pressure regulation in gas mains
- natural gas is transported long distances at high pressure. When it reaches regional areas, the gas pressure has to be lowered. The pressure is lowered again when before it reaches homes at a local station. A GET can be used to recover the energy wasted in the pressure reduction.
- Note, the gas will cool though the process so, it is necessary to pre-heat it before entering the turbine.
- Carbon sequestration / geothermal
- Carbon dioxide that is captured from power stations can be compressed and injected into underground reservoirs. Whilst being stored in the underground caverns the Carbon dioxide is heated by geothermal energy. The heated carbon dioxide can be expanded through a GET and then re-injected into the reservoir.
In an indirect configuration the GET is used as part of a waste heat recovery system – for example an ORC (organic rankine cycle). In such a system a refrigerant gas extracts heat from an object or medium which increases the temperature and pressure of the gas. This pressurised gas is directed through a GET, which turns the turbine and results in lower temperature, lower pressure gas and electricity.
Some examples include:
- Biogas waste heat recovery
- Deprag supplies low power (from 5kW) units to help smaller producers extract electricity from heat that would normally be wasted.
- Recovering heat out of industrial hot water
- Deprag is supplying the GET to a company who can extract electricity from hot water. Hot water is produced in various industrial processes, for example large ship engines, geothermal energy, solar energy and the power industry. The potential for this already proven technology is enormous and game changing in the green energy and energy recovery industries.