IP 68 certified air motors for use under water

01/11/2017 | Air motors |

DEPRAG air motors are used in almost every field of industry – even underwater. The ADVANCED LINE air motor series combines many advantages with their high quality stainless steel drives. Due to the robust design of the external parts in non-corrosive stainless steel and the sealing with two radial shaft sealing rings, these vane motors in the power range 120 W to 1.2 kW are predestined for use underwater.

Air motors in accordance with the IP 68 protection class

The IP (International Protection Class) indicates how well a device or piece of equipment is protected against external influences. Both protection against the penetration of foreign bodies and protection against humidity are indicated by a combination of two digits after the designation “IP” (e.g. IP44). The first digit describes the degree of protection against foreign bodies and ranges from 0 to 6, where “6” stands for complete dust-tightness. The second digit indicates the protection against the ingress of moisture and ranges from 0 to 9, where “8” means that the device is suitable for permanent underwater use.

In the case of IP 68, this means that the air motor is completely dust-tight and protected against permanent immersion in water. This protection class ensures that the motor can function without problems to a depth of at least 1 meter and is therefore ideal for use in demanding environments, such as under water.

For underwater applications it is vital to consider how the vane motor will be deployed and at what water depth it will be operated. If the air motor has to start underwater it can be used up to a depth of 5 metres only. Whereas if it is started on the surface it can be immersed up to a depth of 20 metres.

If there are additional requirements to tackle or if the air motor is needed for use in salt water then further modifications must be made to the housing material and to the sealing, and the internal parts should be coated to prevent corrosion.

Choosing the right air motor

In order to select the most suitable air motor for the customer’s application, intensive advance discussions must take place with the client in order to gain as much insight as possible into the application.

Example: Mixing drive in acidic solution

This example gives a more detailed description of what the DEPRAG engineers can realise for a customer: A motor was needed for use in an acidic solution as a mixing drive for circulating the fluid and evenly stirring in minerals. In order for a motor to be designed which would withstand its surrounding conditions, the following questions needed to be answered:

Which acid was being used?
What concentration of acid is in the fluid or is derived from the fluid: what kind of stainless steel material is stipulated?

The application is the decisive factor! In this case they selected a stainless steel motor from the ADVANCED LINE series with a special requirement to be insensitive to acid. Additionally, a housing was designed which was made from suitable acid-resistant material and with a special sealing to prevent infiltration of any liquid. In order for the air motor to provide the required torque for the application, further consideration of the operating conditions had to be made, such as the available operating pressure, required hose length etc. The technical data of DEPRAG air motors is based on an operating pressure of 6 bar. If the available pressure is lower than this, the torque is reduced proportionally. When using hose lengths longer than 3 metres the hose cross-section opening should be increased correspondingly.

Air motors in the paper industry

Robust stainless steel motors are also sought-after in the paper industry. For example, when preparing the materials used in producing paper: Depending on the type of paper, mechanical or chemical pulp, as well recycled paper fibres are mixed in a certain ratio and dissolved in water. Furthermore, chemical fillers and auxiliary materials are intermixed. This aggressive "mush" must be stirred constantly. The most suitable drive solution for this application would be the air motor special design with acid-resistant stainless steel housing (e.g. AISI 316).

Sterilizable air motors for medical applications

If an air motor should be sterilisable, as often required in the medical technology industry, it should be equipped with special vanes. There are innumerable examples of applications where it is beneficial to speak directly with the manufacturer of the air motor in advance about the task and to describe it in detail before any design work starts.

Air motors for use in clean rooms

For more demanding requirements such as use in cleanroom environments in the food or pharmaceutical industries, the manufacturer can offer a stainless steel motor from their ADVANCED LINE product range which provides sealed, unlubricated, non-corrosive air vane motors. In such cases as these, the motor’s exhaust hose is fed out of the cleanroom. The ADVANCED LINE vane motors are ATEX certified, reversible and even available with integrated holding brake. Their power ranges from 20 W to 1.2 kW, from low speeds to sprinters.

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