Air motors & solutions

The use of air motors in emergency and safety systems

Rémy Davin
by Rémy Davin on Apr 1, 2020 7:21:51 PM

We have had the pleasure of sharing with our readers and customers many application cases for air motors and I must confess that thanks to our experience and the many situations we are presented with and encounter, it is becoming easier and easier to highlight the advantages of air motors. But be careful, the choice of technology and driving energy is never made by chance. Air motors are not the most common motorization solution, but they are becoming unavoidable in certain cases that I would like to remind you of before coming to our subject.

Why an air motor for backup and safety systems? 

In a few words, air motors are synonymous with: compactness, light weight, shimming, ease of use, Atex, harsh environments, flexibility, reliability.

There are many cases in which air motors are used in emergency systems. In all the solutions implemented the safety system takes advantage of the fact that the compressed air can be very easily stored without any time limit. Thus, in case of failure of the electrical system of the installation, the air stored in the tank will allow for a more or less long period of time to maintain the operation of a machine to ensure a "clean" stop or to ensure the safety of an installation, limiting the interventions of restarting to the return of energy. 

The operating time of such a safety system depends on the consumption of the engine, expressed in normo-litres per minute (Nl/min), on the one hand, and on the capacity of the tank, on the other hand. The volume of air available depends on the pressure and the volume of the tank and is expressed in Normo Litre (Nl).

This is not the subject of our blog, but a buffer air tank can also be used outside of backup solutions to compensate for a low flow or pressure in an installation's air network. Indeed, for some applications, which we will develop in a future blog, it is useful to have a boost phenomenon at the start of the air motor. This is possible, without oversizing the whole compressed air installation, by adding a modest air tank on the motor supply circuit, used as a booster.

Some examples of solutions using air motors as a safety system :

  • Valve control: In a process a valve must be closed in case of energy failure. The air motor is the most compact solution, not comparable with conventional spring systems. Other solutions for this type of application are available.
  • Diver ascent assistance by winching, the low speed motor is powered by a 200 bar diving cylinder.
  • Door locking: In the event of a power failure it is not possible to open a container. A pneumatic motor is used to rotate the locking system.

Customer case: a pneumatic motor to make the operation of a shutdown system on loss of electrical energy more reliable.

We have chosen a special case to share in more detail with you and which was proposed to us by one of our distributors in Europe specialising in the design and manufacture of compressed air powered equipment. It involved the renovation of a machine in the food processing sector, which was intended to improve the reliability of the shutdown system on loss of electrical energy. Indeed, the multiple failures of the original system lead to significant production losses.

The system, which is relatively simple in appearance, is broken down into two functions or stages:

The first stage is the inclusion of the pneumatic motorization in the machine's drive train, the motor clutch. This is achieved by a monostable cylinder whose rest position, not powered, corresponds to the engaged position of the motor. When the electricity disappears, the jack moves a roller on the transmission, thus allowing the pneumatic motor to operate. The cylinder is controlled by a monostable 3/2 directional control valve. 

The second step is the rotation of the motor. This step takes place practically synchronously with the clutch. The rotation is maintained until the process in progress is completed. In the same way as for the cylinder, the unidirectional pneumatic motor is controlled by a monostable 3/2 directional valve.

Problem encountered: while the solution seems relatively simple, and the power and torque required to operate the machine during its stop phase are relatively modest, the original pneumatic motors regularly break down.

Diagnosis: As the breakage of the motors occurred at a particular point on the gearbox, we were able to determine, with the help of a test plate, the cause of the breakage.

The solution :  we offered the customer a very compact hybrid air motor solution. Composed of a pneumatic part from our MT05 range that perfectly met the expeted specifications and a gearbox from our MT10 range that allows to increase the maximum torque allowed by the motor from 50 Nm to 120 Nm.

MT07 (40-150 W) 1-565335111

The advantages of this hybrid solution :

Optimization of the power and thus of the consumed flow rate. This is of prime importance for this type of back-up application.
Optimisation of the maximum permissible torque while remaining compatible with the limited space available.
With its ingenious design, this air motor - like all modec air motors - allows easy maintenance at a modest cost. The maintenance of safety systems is another aspect to be taken into account in the solution implemented for such applications.

The specifications of the air motor type MT07:

MT07 (40-150 W) (1)
  • Power 150W
  • Rated speed 75 rpm
  • Nominal torque 20 Nm
  • Direction of rotation clockwise
  • Consumption: 380Nl/min
  • Maximum permissible torque 120Nm

 

 

 

The testimonials we received at the end of this project both from our distributor and the final customer:

 

"We are looking for partners who are willing to commit, who want to get involved, who are innovative and who can offer solutions, Modec gave us relevant advice on a complex project - now we are confident to undertake this type of project in the future because we know we have the right partner".

"The initial tests weren't totally convincing, so we went back to Modec's customer service team for help. Their analysis allowed us to understand that the engine was suitable for the functionality but that some constraints imposed by the machine itself were affecting its performance. With their expertise, we went back to the customer to suggest some modifications and improvements to the machine that would overcome the problems. And they did. Problem solved".

                 

                                 

 

 

 

 

 

 

"Thanks to Modec, the commitment of their technical team and the dialogue we had with them, we were able to solve the problem and we now have a very satisfied customer."

 

 

 

 

 

 

In conclusion, we are committed to surrounding you with competent partners to implement your pneumatic motorization solutions. This will save you and your company time, cost and the opportunity to make continuous improvements to your systems from the simplest to the most complex.

We are counting on you to take the next step forward by presenting us with new challenges or telling us about the pneumatic drive solutions you have implemented.

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