Reducing the Noise Impact of Medical Devices

Medical-care settings are often stressful, making it hard to rest or sleep—both of which are important for healing and recovery. And, as the portability of medical technology continues to rapidly evolve, an increasing number of medical devices and instruments can be utilized in the patient’s home—for example, point-of-care diagnostics, dialysis, and portable oxygen concentrators.

For the best possible experience, medical equipment should be as non-intrusive as possible.

A frequent complaint by patients and other end users is the disruptive noise that medical equipment can generate. Compression therapy equipment, for example, which is used to prevent clotting in a patient’s legs and feet during hospital stays and surgery, utilizes pumps that cycle on and off over long stretches of time. This can interfere with rest and sleep. The volume of the pump may also be too loud, creating a disruptive environment. Therefore, it is essential to minimize the operational sounds of medical devices to optimize the end-user experience.  

For comprehensive information on the impact of noise generating equipment on patients and sound mitigation solutions, download the full white paper, "Advancements in Noise Reduction Techniques for Medical Equipment Manufacturers".

Sources of noise

In pump engineering, there are two main sources of sound generation:

• Structure-borne noise, which includes vibration and other physical structure-generated sound
• Pneumatic noise, which is emitted by flow or movement of air

Common components in medical equipment that often generate noise are:

• Diaphragm pumps
• Solenoid valves
• Fans

Diaphragm pumps tend to be the most substantial source of noise. Their motors rotate a crank that moves a connecting rod up and down, flexing the diaphragm. This action builds pressure or vacuum and generates flow. As the pump operates, it emits vibration across the body of the device.

Solenoid valve and fan noise accompany sound generated by diaphragm pumps during operation. This is caused by the normal actuation of solenoid valves and rotation of the fans as they oscillate the air to keep the equipment cool. 

Since pumps often cycle, their noise levels can be intermittent. This breaks the normal sound conditions in a room, making it difficult to sleep or relax.

Noise reduction solutions for diaphragm pumps

OEMs often report that noise generated by their equipment is the number-one end-user complaint. However, only a few component manufacturers make sound reduction a top priority in their product enhancement activities. Although mufflers can sometimes be added to equipment, this increases the overall dimensions of the device and can cause an increase in back pressure.  

Noise reduction is a key component of Parker’s new product-development projects, especially sound mitigation techniques for diaphragm pumps. We recently tested several methods of sound reduction, including:

• Oversizing the pump
• Using vibration isolating mounts to secure the pump 
• Adding a muffler to the pump
• Adding an additional pump enclosure, lined with soft acoustical foam

Results are shown below:

For structure-born noise, plastic mounting plates that incorporate elastomeric feet reduced the vibration transmission from the pump to the medical device, resulting in a 3-dB noise reduction for an average Parker diaphragm pump. Adding a customized pump enclosure achieved up to 9 dB in sound reduction.

Pneumatic noise was reduced by oversizing the pump and adding a muffler. Oversizing the pneumatic performance of the diaphragm pump and running it at a slower speed reduced the number of pulsatile flow peaks and, in certain applications, achieved a 3-dB sound reduction. Installing an expansion chamber resulted in a 4-dB sound reduction.

A 6 to 9dB noise reduction can be achieved by combining some of these techniques. These are relatively simple and inexpensive solutions that can be easily built into medical devices and diagnostic equipment, creating a much more desirable environment for the end user.

Optimizing the healthcare experience

Enhancing user comfort through medical technology advancements represents the core value proposition for OEMs. Incorporating effective noise reduction solutions into medical device design is essential for a positive patient experience and long-term use of the equipment.

To find out more about sound reduction techniques for medical equipment and what Parker Hannifin has to offer for accessories and application engineering solutions, please contact Parker Precision Fluidics at ppfinfo@parker.com. 

For comprehensive information on the impact of noise generating equipment on patients and sound mitigation solutions, download the full white paper, "Advancements in Noise Reduction Techniques for Medical Equipment Manufacturers".

This blog was contributed by Richard Whipple, marketing communications manager, Parker Precision Fluidics

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